Document:

<PAGE>   1
                                                                   EXHIBIT 10.15

                       ASSIGNMENT OF LEASE AND ACCEPTANCE

          This Assignment of Lease and Acceptance (the "Assignment") is entered
as of the 17th day of November, 1999, between Keyvan Rafei ("Assignor"), and
Advanced Switching Communications, Inc., a Delaware corporation ("Assignee"),
and is consented to by The Equitable Life Assurance Society of the United
States ("Landlord").

          WHEREAS, Landlord and Assignor entered into a Lease Agreement dated
May 29, 1992 (the "Lease"), for premises containing approximately 21,04l square
feet of Net Rentable Area (the "Premises") in the building located at 8300-8330
Boone Boulevard, Vienna, Virginia, known as The American Center (the
"Building"); and

          WHEREAS, the Lease is scheduled to expire on August 31, 2002; and

          WHEREAS, Assignor wishes to assign its interests in the Lease to
Assignee; and

          WHEREAS, Landlord is willing to consent to the Assignment on the
terms and conditions contained herein.

          NOW, THEREFORE, in consideration of the foregoing, and other good and
valuable consideration, the receipt and sufficiency of which are acknowledged
by the parties, the parties agree as follows:

         1.   Assignment and Warranty. Assignor hereby transfers, assigns and
sets over to Assignee, all of its right, title and interest in and to the Lease
and to all subleases related to the Premises, effective as of February 1, 2000
(the "Effective Date"). A true and complete copy of the Lease and all
amendments and subleases is attached hereto as Exhibit A. Assignor hereby
warrants that he has the right to assign this Lease upon the terms set forth
herein, that except for the subleases summarized on Exhibit B attached hereto,
he has not conveyed any sublease or other rights to any party, that all such
subleases are in full force and effect, and that there will be no undischarged
obligations of Assignor as of the Effective Date. Concomitant with the
execution hereof, Assignor provides Assignee with completed estoppel

<PAGE>   2

certificates for all sublessees on substantially the same form as attached
hereto as Exhibit C.

          2.  Condition of the Premises. Assignee accepts the Premises in its
then "as is" condition as of the Effective Date, which condition shall be
substantially the same as the condition on the date of this Assignment first
set forth above.

          3.  Acceptance. Assignee assumes the obligations under the Lease as
of the Effective Date and agrees to make all payments to Landlord and keep all
covenants and agreements of Assignor in the Lease as of the Effective Date.

          4.  Other Covenants of the Parties.

              (a)   Except as otherwise expressly provided herein, the
execution of this Assignment shall in no way be deemed, construed or otherwise
operate to modify the Lease in any way.

              (b)   Notwithstanding anything set forth herein, Assignee shall
have no obligation whatsoever for the undischarged obligations of Assignor
under the Lease which arise prior to the Effective Date.

              (c)   Landlord agrees to permit Assignee to occupy the Premises
under the terms set forth in this Assignment and pursuant to the Lease,
irrespective of any default of Assignor under the Lease. In the event of a
default by Assignor under the Lease prior to the Effective Date, Landlord
agrees that it will not terminate the Lease based upon such default, and that
Assignee shall have the right to occupy the Premises as of the Effective Date,
upon the same terms and conditions as set forth in the Lease. Assignee
understands and agrees that Landlord shall have no obligation whatsoever to
deliver possession of the Premises to Assignee.

<PAGE>   3

              (d)   Assignor agrees to fully vacate the Premises not later than
the Effective Date, in the condition agreed to above, so that the Assignee may
occupy the same on the Effective Date. In the event the Assignor fails to so
vacate the Premises for any reason whatsoever, then in addition to any other
remedies as may be available to Assignee, the Assignor agrees to pay the
Assignee an amount equal to the daily rent on the Premises, as liquidated
damages and not as a penalty, for each day until Assignor has vacated and
provided the Premises in the required condition. Assignor and Assignee agree
that actual damages are difficult or impossible to quantify and that the above
payment represents a reasonable method for ascertaining the damages to Assignee.

          5.  Landlord's Consent. Landlord consents to the Assignment upon the
express conditions that: (i) on or before execution of this Assignment,
Assignor shall deliver to Landlord the most recent "as built" floorplans for
the existing conditions on the eighth (8th) floor of the Building, and all
occupancy permits for each of the three (3) suites in the Premises; (ii) Tenant
shall pay, on or before the Effective Date, Landlord's counsel fees incurred in
the drafting and negotiation of this Assignment (which fees shall not exceed
$1,500.00); and (iii) there shall be no further assignments of the Lease
without first obtaining the prior written consent of Landlord, as required
under the Lease. Assignor and Assignee expressly consent to each of the
foregoing conditions.

          6.  Release. As of the Effective Date, Assignor and Landlord shall
have no further claim against the other by reason of said Lease, except as
otherwise expressly provided herein and except for the holdover provisions of
said Lease, which shall become effective if Assignor has not fully vacated the
Premises on or before the Effective Date; provided, however, that all monetary
obligations of the Assignor incurred pursuant to the Lease prior to the
Effective
<PAGE>   4
Date and not as yet performed, shall continue in full force and effect until
fully performed by the Assignor.

          7.  Brokers. The parties acknowledge that Julien J. Studley has acted
as broker for Assignor, Transwestern Carey Winston has acted as broker for
Assignee, and Cassidy & Pinkard has acted as broker for Landlord. Each party
represents and warrants that it shall be solely responsible for paying any fees
or commission due to its own broker, and will indemnify the other parties
hereto for any claims, including all costs, expenses, attorneys' fees or other
liability for commissions or other compensation or charges claimed by any other
broker or agent claiming the same by or through such party.

          8.  Headings. Headings contained in this Assignment are for
convenience only and are not substantive to the provisions of this Assignment.

          9.  Meanings. Except as otherwise expressly provided herein, all
defined terms shall have the same meanings as provided in the Lease.

<PAGE>   5

          IN WITNESS WHEREOF, the parties have executed this Assignment as of
the date noted above.

<TABLE>
<S>                                   <C>
WITNESS/ATTEST:                        ASSIGNOR:
            [SIG]                      /s/ KEYVAN RAFEI
------------------------------         ------------------------
                                       Name: Keyvan Rafei

WITNESS:                               ASSIGNEE:

                                       Advanced Switching Communications, Inc.

            [SIG]                      By: /s/ HARRY J. D'ANDREA
------------------------------            ------------------------
                                       Name:  Harry J. D'Andrea
                                       Title: CFO

WITNESS/ATTEST:                        LANDLORD:

                                       The Equitable Life Assurance
                                       Society of the United States

            [SIG]                      By: /s/ BRENDA E. MCKINNEY
------------------------------            ------------------------
                                       Name: Brenda E. McKinney
                                       Title: Investment Officer
</TABLE>

<PAGE>   6

                                LIST OF EXHIBITS

EXHIBIT A     American Center Lease Agreement dated May 29, 1992
              Met Life International Real Estate Equity Shares, Inc. and
              Keyvan Rafie

              Agreement of Sublease dated November 24, 1998
              Global Learning Systems and Keyvan Rafei

              Consent to Sublease dated December 16, 1998
              The Equitable Life Insurance Society of the United States and
              Keyvan Rafei

              Agreement of Sublease dated October 27, 1997
              Tenet HealthSystems and Keyvan Rafei

              Landlord's Consent dated November 1997
              Met Life International Real Estate Equity Shares, Inc., Keyvan
              Rafei and Tenet HealthSystems, Inc.

              Sublease dated April 13, 1998
              Tenet HealthSystems Medical, Inc. and ChoicePoint Services, Inc.

              Consent to Sublease dated May 29, 1998
              The Equitable Life Assurance Society of the United States, Keyvan
                  Rafei, Tenet HealthSystems Medical, Inc. and ChoicePoint
                  Services, Inc.

Exhibit B     Summary of Sublease Agreements

EXHIBIT C     Form Estoppel Certificate

<PAGE>   7

                        AMERICAN CENTER LEASE AGREEMENT

          THIS LEASE AGREEMENT (the "Lease") is made and entered into on this
the 29th day of May, 1997 between Met Life International Real Estate Equity
Shares, Inc., a Delaware Corporation ("Landlord") and Keyvan Rafie, a sole
proprietorship, ("Tenant").

                                  WITNESSETH:

          1.      Definitions.

          (a)     The "Project" shall mean the American Center Office Complex,
being the real property described in Exhibit "A" attached hereto and
incorporated herein and improvements constructed thereon.

          (b)     "Premises" shall mean the space outlined on the floor plan
attached to this Lease as Exhibit "B" incorporated herein. The Premises are
stipulated for all purposes to contain approximately 21,041 square feet of "Net
Rentable Area" (as below defined); provided, however that Landlord may, upon
completion of the Premises, cause precise measurements of the Project, the
Building (as below defined) and the Premises to be made, and Base Rental (as
below defined) shall be adjusted upward or downward accordingly. The Premises
are located in the office building (the "Building") located at 8330 Boone
Boulevard, Suite 800, Vienna, in Fairfax, Virginia.

          (c)     "Base Rental" shall mean the sum of (i) $378,738.00 per annum
for the first (1st) through the fifth (5th) year of the Lease Term (hereafter
defined) and (ii) $410,299.50 per annum for the sixth (6th) through the tenth
(10th) year of the Lease Term. The Base Rental payable beginning on the first
(1st) day of the sixth (6th) year of the Lease Term is the sum of the Base
Rental payable during the first (1st) year of the Lease Term plus adjustments
that accrued from time to time during years one (1) through five (5) of the
Lease Term pursuant to Exhibit "D" attached hereto plus an increase of $1.50
per square foot of Net Rentable Area contained within the Premises. The Base
Rental due for the first (1st) month of the Lease Term (hereinafter defined)
during which Base Rental is due, has been deposited with Landlord by Tenant
contemporaneously with the execution hereof.(1)

          (d)     "Commencement Date" shall mean the later of August 14, 1992
or the date specified in paragraph 3 (c) hereof.

------------------------

(1) Landlord shall provide Tenant a monthly rental credit equal to $2,630.l2
for months two (2) through thirty-seven (37).

                                       1
<PAGE>   8
          (e) "Lease Term" shall mean a term commencing on the Commencement
Date and continuing until 120 calendar months after the first day of
the first full month following the Commencement Date.

          (f) "Security Deposit" shall mean the sum of $31,561.50. The Security
Deposit(2) deposited with Landlord by Tenant(3).

          (g) "Common Areas" shall mean those areas devoted to lobbies,
corridors, all elevator foyers, restrooms, mechanical rooms, janitorial
closets, electrical and telephone closets, vending areas and other similar
facilities provided for the common use or benefit of tenants generally and/or
the public.

          (h) "Service Area" shall mean those areas within the outside walls of
the Building used for elevator mechanical rooms, building stairs, fire towers,
elevator shafts, flues, vents, stacks, pipe shafts, and vertical ducts (but
shall not include any such areas for the exclusive use of the particular
Tenant).

          (i) "Net Rentable Area" of the Premises shall mean the gross area
within the inside surface of the outer glass or other material comprising the
exterior walls of the Premises, to the mid-point of any walls separating
portions of the Premises from those of adjacent tenants and to the Common Area
or Service Area side of walls separating the Premises from Common Areas and
Service Areas, subject to the following:

              (1)   Net Rentable Area shall not include any Service Areas.

              (2)   Net Rentable Area shall include a prorata part of the
Common Areas on the floor on which the Premises are located, such proration
based upon the ratio of the Net Rentable Area within the Premises to the total
Net Rentable Area on such floor, both determined without regard to the Common
Areas. The Common Area on floor(s) upon which the Premises are located shall
never exceed: 2,711 square feet and may be adjusted as determined by Landlord
from time to time to confirm such allocation to changes in the configuration or
rented spaces and Common Areas upon such floor.

              (3)   Net Rentable Area shall include any columns and/or
projection(s) which protrude into the Premises and/or the Common Areas.

------------------------

(2) shall be

(3) in the form of a Letter of Credit drawn against a bank reasonably
satisfactory to Landlord within fifteen (15) days of execution hereof.

                                       2

<PAGE>   9

          (j) "Exterior Common Areas" shall mean those areas of the Project
which are not located within the Building and which are provided and maintained
for the common use and benefit of Landlord and tenants of the Project generally
and the employees, invitees and licensees of Landlord and such tenants;
including without limitation all parking areas, enclosed or otherwise; all
streets, sidewalks and landscaped areas located within the Project.

          (k) The "Improvements", when used herein, shall mean those
improvements to the Premises which Landlord has agreed to provide when
approving the plans and specifications (the "Plans") described on Exhibit "0",
attached (or to be attached) hereto and incorporated herein for all purposes.
Except to the extent otherwise agreed (and described on an addendum to the
Plans), the installation of the Improvements shall be installed by Landlord at
Tenant's expense. "Building Standard" shall mean the type, brand and/or quality
of materials Landlord designates from time to time to be the minimum quality to
be used in the Building or the exclusive type, grade or quality of material to
be used in the Building.(4)

          2.  Lease Grant. Subject to and upon the terms herein set forth,
Landlord leases to Tenant and Tenant leases from Landlord the Premises.

          3.  Lease Term.

          (a) This Lease shall continue in force during a period beginning on
Commencement Date and continuing until the expiration of the Lease Term, unless
this Lease is sooner terminated or extended to a later date under any other
term or provision hereof.

          (b) if by August 14, 1992 the Improvements have not been
substantially completed pursuant to the Plans (as determined by Landlord's
architect in his sole and absolute discretion), due to omission, delay or
default by Tenant or anyone acting under or for Tenant, Landlord shall have no
liability because of such delays, and the obligations of this Lease (including,
without limitation, the obligation to pay rent) shall nonetheless commence as
of the Commencement Date.

          (c) If, however, the Improvements are not substantially completed (as
determined by Landlord's architect in his sole and absolute discretion) by
August 14, 1992, due to any reason other than an omission, delay or default by
Tenant or someone acting under or for Tenant, then, as Tenant's sole remedy for
the delay in Tenant's occupancy of the Premises, Commencement Date shall be
delayed and the rent herein provided shall not commence until the earlier to
occur of actual occupancy by Tenant of any portion of the Premises or
substantial completion of the Improvements.

------------------------

(4) Landlord shall build out Tenant's demised premises to suit in accordance
    with attached Exhibits "C" and "O". In addition, Landlord shall provide
    Tenant an allowance equal to $2.00 per square foot to improve the premises
    anytime between thirty six (36) and sixty (60) months of the lease term.

                                       3

<PAGE>   10

          4.  Use. The Premises shall be used for office purposes and for no
other purpose. Tenant agrees not to use or permit the use of the Premises for
any purpose and uses incidental thereto which is illegal or which, in
Landlord's opinion, creates a nuisance or which would increase the cost of
insurance coverage with respect to the Building.

          5.  Base Rental.

          (a) Tenant agrees to pay during the Lease Term, to Landlord, without
any setoff or deduction whatsoever the Base Rental, and all such other sums of
money payable by the Tenant hereunder as additional rent (whether or not
expressly characterized as additional rent), all of which are sometimes herein
collectively called "rent", for the nonpayment of which Landlord shall be
entitled to exercise all such rights and remedies as are herein provided in the
case of the nonpayment of Base Rental. If no earlier due date is expressly
specified herein for the payment of additional rent, additional rent shall be
payable in full no later than the due date of the next following installment of
Base Rental. The annual Base Rental for each lease year or portion thereof
during the Lease Term, together with any estimated adjustments thereto pursuant
to Exhibit D hereof, shall be due and payable in advance in twelve (12) equal
installments on the first day of each calendar month during the Lease Term, and
Tenant hereby agrees to pay such Base Rental and any adjustments thereto as
additional rent to Landlord at Landlord's address provided herein (or such
other address as may be designated by Landlord in writing from time to time)
monthly, in advance, and without demand. If the term of this Lease commences on
a day other than the first day of a month or terminates on a day other than the
last day of a month, then the installments of Base Rental and any adjustments
thereto for such month or months shall be prorated, based on the number of days
in such month.

          (b) In the event any installment of rent is not paid(5) of when due
and payable, Tenant shall pay a late charge of four percent (4%) of the
delinquent amount.

          6.  Services to be Furnished by Landlord. Landlord agrees to furnish
Tenant the following services:

          (a) Hot and cold water at those points of supply provided for general
use of other tenants in the Building and pantry included within premises,
central heat and air conditioning in season, at such temperatures and in such
amounts as are considered by Landlord to be standard or as required by
governmental authority; provided, however, heating and air conditioning service
at times other than for "Normal Business Hours" for the Building (which are
7:30 a.m. to 6:00 p.m. on Mondays through Fridays and 8:00 a.m. to 1:00 p.m. on
Saturdays, exclusive of "Normal Business Holidays", as hereinafter defined),
shall be furnished only upon the written request of Tenant delivered to
Landlord prior to 3:00 p.m. at least 1 business day in advance of the date such
usage is requested. As used herein, Normal Business Holidays shall include all
hours after 1:00 p.m. on Saturdays, all day on Sundays and all days

------------------------

(5) within five (5) days

                                       4

<PAGE>   11

observed by the Commonwealth of Virginia or the Federal Government as legal
holidays and such other days designated as legal holidays by the applicable
building service union employee's service contract and/or by the applicable
operating engineer's contract. Tenant shall bear the entire cost of additional
service allocable to the Premises as such costs are determined and allocated by
Landlord from time to time.

          (b) Routine maintenance and electrical lighting service for all
Exterior Common Areas(6) and Service Areas in the manner and to the extent
deemed by Landlord to be standard.

          (c) Janitor service, Mondays through Fridays, exclusive of normal
business holidays; provided, however, if Tenant's floor covering or other
improvements require special treatment, Tenant shall pay the additional
cleaning cost attributable thereto as additional rent upon presentation of a
statement therefor by Landlord. Tenant shall cooperate with Landlord's
employees in the furnishing by Landlord of janitorial services at such times
(including Normal Business Hours) as Landlord elects to have the necessary work
performed; provided, however, that janitorial services performed by Landlord
during Normal Business Hours shall be performed in such a manner as to not
unreasonably interfere with Tenant's use of the Premises.

          (d) Subject to the provisions of Paragraph 12, facilities to provide
all electrical current required by Tenant in its use and occupancy of the
Premise.

          (e) All Building Standard fluorescent bulb replacement in the Premises
and fluorescent and incandescent bulb replacement in the Common Areas and
Service Areas.

          (f) Landlord may elect to provide security in the form of limited
access to the Building during other than Normal Business Hours. In such event
Landlord may require those tenants requesting access to the Building during
other than Normal Business Hours, to pay a fee for such access partially to
reimburse Landlord for the cost of the system which limits after-hours access.
Landlord, however, shall have no liability to Tenant, its employees, agents,
invitees or licensees for losses due to theft or burglary, or for damages
done by unauthorized persons on the Premises and neither shall Landlord be
required to insure against any such losses. Tenant shall cooperate fully in
Landlord's efforts to maintain security in the Building and shall follow all
rules and regulations promulgated by Landlord with respect thereto.

          The failure by Landlord to any extent to furnish or the interruption
or termination of these defined services in whole or in part, resulting from
causes beyond the reasonable control of Landlord shall not render Landlord
liable in any respect nor be construed as an eviction of Tenant, nor work an
abatement of rent, nor relieve Tenant from the obligation to fulfill any
covenant or agreement hereof. Should any of the equipment or machinery used in
the provision of such services for any cause cease to function properly, tenant
shall have no claim for offset or abatement of rent or damages on account of an
interruption in service occasioned thereby or

------------------------

(6) Common Areas

                                       5

<PAGE>   12

resulting therefrom.

          7.  Improvements to be Made by Landlord. Except for the Improvements,
all installations and improvements now or hereafter placed on the Premises
shall be for Tenant's account and at Tenant's cost (and Tenant shall pay ad
valorem taxes and increased insurance thereon or attributable thereto), which
cost shall be payable by Tenant to Landlord in advance as additional rent.

          8.  Maintenance and Repair of Premises by Landlord. Except as
otherwise expressly provided herein, Landlord shall not be required to make any
repairs to the Premises.(7)

          9.  Graphics. Tenant shall not erect or install any sign or other
type display whatsoever, either upon the exterior of the Building, upon or in
any window or in any lobby, without the prior express written consent of
Landlord. The color and fabric of the lining of all drapes (or if unlined, the
draperies themselves) which Tenant desires to place on exterior windows or
openings of the Building must be approved by Landlord prior to the installation
thereof so that a uniform color and appearance may be preserved from the
exterior of the Building. Landlord agrees to furnish a directory of the names
and locations of its tenants and to install and maintain the same at a
convenient location in the lobby of the Building. The initial listing of the
name and room number of Tenant shall be furnished without charge. The listings
of additional names or room numbers and changes or revisions of listings shall
be made by Landlord at the cost of Tenant.

          10. Care of the Premises by Tenant. Tenant agrees not to commit or
allow any waste to be committed on any portion of the Premises and at the
termination of this Lease to deliver up the Premises to Landlord in as good
condition as at the date of the commencement of the term of this Lease,
ordinary wear and tear and insured casualty losses excepted.

          11. Repairs and Alterations by Tenant. Tenant covenants and agrees
with Landlord, at Tenant's own cost and expense, to repair or replace any
damage done to the Building, or any part thereof, caused by Tenant or Tenant's
agents and employees, and such repairs shall restore the Building to as good as
condition as it was in prior to such damage, and shall be effected in
compliance with all applicable laws; provided, however, if Tenant fails to make
such repairs or replacements promptly, Landlord may, at its option, make
repairs or replacements, and Tenant shall pay the cost thereof to the Landlord
on demand as additional rent. Tenant agrees with Landlord not to make or allow
to be made any alterations to the Premises, install any vending machines on the
Premises, or place signs on the Premises which are visible from outside the
Premises, without first obtaining the express written consent of Landlord in
each such instance, which consent may be given on such conditions as Landlord
may elect. Any and all alterations to the Premise shall become the property of
Landlord upon Termination of this Lease (except

------------------------

(7) Notwithstanding the foregoing Landlord shall maintain the building and
    building systems in a manner consistent with a First Class building in
    Fairfax County, Virginia.

                                       6
<PAGE>   13
for moveable equipment or furniture owned by Tenant). Landlord may, nonetheless,
require Tenant to remove any and all fixtures, equipment and other improvements
installed on the Premises upon expiration or prior termination of the Lease
Term. In the event that Landlord so elects, and Tenant fails to remove such
improvements, Landlord may remove such improvements at Tenant's cost, and Tenant
shall pay Landlord on demand the cost of restoring the Premises to Building
Standard.

       12. Use of Electrical Services by Tenant. Tenant's use of electrical
services furnished by Landlord shall be subject to the following:

       (a) Tenant's electrical equipment shall be restricted to that equipment
which individually does not have a rated capacity greater than .5 kilowatts per
hour and/or require voltage other than 120/208 volts, single phase.
Collectively, Tenant's equipment shall not have an electrical design load
greater than an average of 2 watts per square foot.

       (b) Tenant's lighting shall not have a design load greater than an
average of 2 watts per square foot.

       (c) Landlord shall be entitled to enter the Premises to perform an audit
or survey of electrical use thereon from time to time. Tenant's consumption of
electrical services shall not exceed either the rated capacities and/or design
loads set forth in Paragraphs 12(a) and 12(b) above nor shall it generate heat
in excess of that which Landlord's air conditioning system is designed to
handle. In the event that Tenant elects to add equipment and/or lighting to the
Premises that will cause Tenant's consumption of electrical services to exceed
either the rated capacities and/or design loads set forth in Paragraphs 12(a)
and 12(b) above or that will generate heat in excess of that which Landlord's
air conditioning system is designed to handle, Tenant shall obtain Landlord's
prior written approval of such equipment and/or lighting subject to the
following:

       (i) Tenant shall pay for all costs of installation and maintenance of
submeters, wiring, additional air conditioning systems and other items required
by Landlord, in Landlord's discretion, to accommodate Tenant's excess design
loads and capacities or heat production.

       (ii) Tenant shall pay to Landlord, upon demand, the cost of the excess
demand and consumption of electrical service at rates determined by Landlord
(which rates shall be in accordance with any applicable laws) as well as all
costs of operating additional air conditioning systems deemed necessary by
Landlord on account of Tenant's excess consumption.

       (iii) Landlord may, at its option, upon not less than thirty (30) days'
prior written notice to Tenant, discontinue the availability of any or all
utility service and in such event Tenant shall contract directly with such
public utility for the supplying of such additional utility service to the
Premises.

                                       7
<PAGE>   14

       13. Parking. During the Lease Term, Tenant shall have the non-exclusive
use in common with Landlord, other tenants of the Building, their guests and
invitees, of the non-reserved common automobile parking areas, driveways, and
footways, subject to rules and regulations for the use thereof as prescribed
from time to time by Landlord. Landlord reserves the right to designate parking
areas within the Project or in reasonable proximity thereto, for Tenant and
Tenant's agents and employees. Cars not parked according to the rules and
regulations promulgated by Landlord may be towed at the owner's expense. Tenant
shall provide Landlord with a list of all license numbers for the cars owned by
Tenant, its agents and employees from time to time upon demand. In the event
that Tenant, its agents and employees, park in locations other than those
assigned to Tenant, Landlord reserves the right to charge Tenant as additional
rental hereunder Twenty-Five Dollars ($25) per diem for each such occurrence in
addition to towing such cars at Tenant's expense. Landlord will designate
special parking areas located within the Project for reserved parking for
tenants of the Project who will rent such parking spaces. In the event Tenant
leases any such rental parking spaces from Landlord, the terms and conditions of
such lease shall be as set forth in that certain Parking Space Rental Agreement
attached hereto as Exhibit "F" and incorporated herein by reference.

       14. Laws and Regulations. Tenant agrees at Tenant's expense to comply
with all applicable laws, ordinances, rules, and regulations of any governmental
entity or agency having jurisdiction of the Premises.

       15. Building Rules. Tenant will comply with the rules of the Building and
Project reasonably adopted and altered by Landlord from time to time and will
cause all of its agents, employees, invitees and visitors to do so; all changes
to such rules will be sent by Landlord to Tenant in writing. The initial rules
for the Building and the Project being attached hereto as Exhibit "E" and
incorporated herein for all purposes.

       16. Entry by Landlord. Tenant agrees to permit Landlord or its agents or
representatives to enter into and upon any part of the Premises at all
reasonable hours (and in emergencies at all times) to inspect the same, or to
show the Premises to prospective purchasers, mortgagees, tenants, or insurers,
to clean or make repairs, alterations or additions thereto, and Tenant shall not
be entitled to any abatement or reduction of rent by reason thereof. Tenant
agrees to cooperate with Landlord in event of emergencies, including, without
limitation, evacuation at Landlord's oral request in the event of any situation
deemed by Landlord as an emergency.

       17. Assignment and Subletting. Tenants shall not assign, sublease or
transfer any or all of the Premises without the prior written consent of
Landlord, such consent shall not be unreasonably withheld. In the event of any
such assignment or subletting consented to by Landlord, Tenant shall remain
fully and primarily liable for the payment of rent due under this Lease and for
the performance of all the covenants, agreements, terms, conditions and
provisions under this Lease. Additionally, Tenant's assignee or sublessee shall
be required to assume all of Tenant's obligations under this Lease. The Landlord
hereby grants to Tenant the right to sublease up to fifty percent (50%) of the
Premises without the Landlord participating in any of

                                       8
<PAGE>   15

the profit derived from said subleasing. In the event that Tenant desires to
sublease more than fifty percent (50%) of the Premises, Tenant shall give
Landlord thirty (30) days written notice of Tenant's intention to do so. Within
thirty (30) days of receipt of said notice, Landlord shall have the right to:

       (a)    Take possession of(8) or;

       (b)    Participate in fifty percent (50%) of profits derived from said
              subleasing or;

       (c)    Notify Tenant, in writing, of Landlord's consent to allow Tenant
              to sublease said space.

       18.    Mechanic's Liens. Tenant will not suffer or permit any mechanic's
lien or liens to be placed upon the Premises or the Building arising out of any
work contracted for or authorized by Tenant in respect to the Premises and
nothing in this Lease shall be deemed or construed in any way as constituting
the consent or request of Landlord, express or implied, by inference or
otherwise, to any person for the performance of any labor or the furnishing of
any materials to the Premise or any part thereof, nor as giving Tenant any
right, power, or authority to contract for or permit the rendering of any
services or the furnishing of any materials that would give rise to any
mechanics' or other liens against the Premises. In the event any such lien is
attached to the Premises or Tenant's interest therein Tenant shall immediately
cause same to be released, and if Tenant fails to do so, then, in addition to
any other right to remedy of Landlord, Landlord may, but shall not be obligated
to, discharge the same. Any amount paid by Landlord for any of the aforesaid
purposes and costs incurred by Landlord with respect thereto, shall be paid by
Tenant to Landlord on demand as additional rent.

       19.    Insurance.

       (a)    Landlord shall maintain fire and extended coverage insurance on
the Building and the Premises in such amounts as Landlord or its mortgages shall
require. payable solely to Landlord or the mortgages of Landlord as their
interests shall appear. Tenant shall maintain, at its expense, fire and extended
coverage insurance on all of its personal property, including removable trade
fixtures, equipment, installations and contents located in the Premise and in
such additional amounts as are necessary to meet Tenants' obligations pursuant
to paragraph 23 hereof. Tenant shall, at Landlord's request from time to time,
provide Landlord with current certificates of insurance evidencing Tenant's
compliance with this Paragraph 19(a) and Paragraph 19(b). Tenant shall obtain
the agreement of Tenant's insurers to notify Landlord than policy is due to
expire at least 10 days prior to such expiration.

----------------

(8) the proposed sublease portion of the premise

                                        9
<PAGE>   16

       26.    Events of Default/Remedies.

              (a) The following events shall be deemed to be events of default
by Tenant under this Lease (i)(16) or Tenant shall fail to comply with any
provision of this Lease or any other agreement between Landlord and Tenant, all
of which terms, provisions and covenants shall be deemed material(17) (ii) the
leasehold hereunder demise shall be taken on execution or other process of law
in any action against Tenant or Tenant shall become insolvent or unable to pay
its debts as they become due, or Tenant notifies Landlord that it anticipates
either condition; (iii) Tenant shall fail to move into and take possession of
the Premises(18) when the Premises are ready for occupancy, it shall at any time
vacate the Premise without Landlord's prior written approval; (iv) Tenant takes
any action to, or notifies Landlord that Tenant intends to file a petition under
any section or chapter of the National Bankruptcy Code, as amended, or under any
similar existing or subsequently enacted law or statute of the United States or
any State thereof, or a petition shall be filed against Tenant under any such
statute or (v) a receiver or trustee shall be appointed for Tenant's leasehold
interest in the Premises or for all or a substantial part of the assets of
Tenant.

              (b) Upon the occurrence of any event or events of default by
Tenant, whether enumerated in this Paragraph or not, Landlord shall have the
option to pursue any one or more of the following remedies without any notice or
demand for possession whatsoever (and without limiting the generality of the
foregoing, Tenant hereby specially waives notice and demand for payment of rent
or other obligations due and waives any and all other notices or demand
requirements imposed by applicable law): (i) terminate this Lease in which event
Tenant shall immediately surrender the Premises to Landlord; (ii) terminate
Tenant's right to occupy the Premises and re-enter and take possession of the
Premises (without terminating this Lease); (iii) enter upon the Premises and do
whatever Tenant is obligated to do under the terms of this Lease; and Tenant
further agrees that Landlord shall not be liable for any damages resulting to
the Tenant from such action; and (iv) exercise all other remedies available to
Landlord at law or in equity, including, without limitation, injunctive relief
of all varieties.

-------------------

       (16) Tenant shall fail to comply with any provision of this Lease (or any
other agreement between. Landlord and Tenant) requiring the payment of money and
such failure shall continue for a period of ten (10) days following written
notice thereof from Landlord to Tenant of such default;

       (17) and such failure shall continue for more than thirty (30) days
following notice thereof from Landlord to Tenant:

       (18) within twenty (20) days of

                                       13

<PAGE>   17
        In the event Landlord elects to re-enter or take possession of the
Premises after Tenant's default(19), Tenant hereby waives notice of such reentry
or repossession and of Landlord's intent to re-enter or take possession.
Landlord may, without prejudice to any other remedy which it may have for
possession or arrearage in rent, expel or remove Tenant and any other person who
may be occupying said Premises or any part thereof. Whether or not Landlord
elects to terminate this Lease in connection with a default by Tenant, Landlord
shall be entitled to reimbursement of all cost and expenses (including, without
limitation, tenant finish costs and commissions) incurred in respect of a
reletting all or a portion of the Premises occasioned by Tenant's default. In
addition, interest shall accrue on sums due hereunder from Tenant but not paid,
at the lesser of 18% per annum or the highest rate permitted by applicable law.
The provisions of Paragraph 28 hereof shall apply with respect to the period
from and after written notice to Tenant of termination. All of Landlord's
remedies shall be cumulative and not exclusive. Forbearance by Landlord to
enforce one or more of the remedies herein provided upon an event of default
shall not be deemed or construed to constitute a waiver of such default.

        (c)     This Paragraph 26 shall be enforceable to the maximum extent not
prohibited by applicable law, and the unenforceability of any portion thereof
shall not thereby render unenforceable any other portion. To the extent any
provision of applicable law request some action by Landlord to evidence or
effect the termination of this Lease or to evidence the termination of Tenant's
right of occupancy, Tenant and Landlord hereby agree that written notice, to
Tenant, or which comes to the attention of Tenant, which expressly reflects
Landlord's intention to terminate, shall be sufficient to evidence and effect
their termination herein provided for.

        (d)     **In no event shall Tenant have the right to terminate or
rescind this Lease as a result of Landlord's default of any covenant or
agreement contained in this Lease or as a result of the breach of any promise or
inducement hereof, whether in this Lease or elsewhere. Tenant hereby waives such
remedied of termination and rescission and hereby agrees that Tenant remedies
for default hereunder and for breach of any promise or inducement shall be
limited to a suit for damages and/or injunction. In addition, ** Tenant hereby
covenants that, prior to the exercise of any such remedies, it will give the
mortgages on the Building notice and a reasonable time to cure any default by
Landlord.(20)

        27.     Peaceful Enjoyment. Tenant shall, and may peacefully have, hold,
and enjoy the Premises, subject to the other terms hereof, provided that Tenant
pays the rent and other sums herein recited to be paid by Tenant and performs
all of Tenant's covenants and agreements herein contained. This covenant and any
and all other covenants of Landlord shall be binding

---------------------

        (19) provided the aforementioned notice of default has been given to
Tenant as specified in Paragraphs 26(a) and 26(b).

        (20) provided Tenant has been given written notice of such mortgages and
an address where notices should be sent.

                                       14
<PAGE>   18

upon Landlord and its successors only with respect to breaches occurring during
its or their respective periods of ownership of the Landlord's interest
hereunder.(21)

        28.     Holding Over. In the event of holding over by Tenant without
Landlord's written consent after the expiration or other termination of this
Lease or in the event Tenant continues to occupy the Premises after the
termination of Tenant's right of possession pursuant to Paragraph 26(b) (ii)
hereof, Tenant shall, throughout the entire holdover period, pay rent equal on a
per diem basis, to twice the Base Rental and additional Base Rental, as adjusted
or increased under Exhibit "D" hereto, which would have been applicable had the
term of this Lease continued through the period of such holding over by Tenant.
No holding over by Tenant after the expiration of the term of this Lease shall
be construed to extend the term of this Lease.

        29.     Subordination to Mortgage. Tenant agrees that this Lease is and
shall be junior and subordinate to any first mortgage, added of trust or other
lien presently existing or hereafter arising upon the Premises, upon the
Building or upon the Project as a whole or any part thereof, and to any
renewals, modifications, consolidations, replacements, refinancing, and
extensions thereof, but Tenant agrees that any such first mortgagee shall have
the right at any time to subordinate such mortgage, added of trust or other lien
to this Lease on such terms and subject to such conditions as such mortgagee may
deem appropriate in its discretion. Landlord is hereby irrevocably vested with
full power and authority to subordinate this Lease to any mortgage, deed of
trust or other lien now existing or hereafter placed upon the Premises, the
Building or the Project as a whole or any part hereof, and to any renewals,
modifications, consolidations, replacements, refinancing and extensions thereof,
and Tenant agrees within fifteen (15) days to execute such further instruments
subordinating this Lease or attorning to the holder of any such liens as
Landlord may request. In the event that Tenant should fail to execute any
instrument of subordination herein required to be executed by Tenant within
fifteen (15) days of Landlord's demand, Tenant hereby irrevocably constitutes
Landlord as its attorney-in-fact to execute such instrument in Tenant's name,
place and stead, it being agreed that such power is one coupled with an
interest. Tenant agrees that it will from time to time upon request by Landlord
execute and deliver to such persons as Landlord shall request a statement in
recordable form certifying that this Lease is unmodified and in full force and
effect (or if there have been modifications, that the same is in full force and
effect as so modified), stating the dates to which rent and other charges
payable under this Lease have been paid, stating that Landlord is not in default
hereunder (or if Tenant alleges a default stating the nature of such alleged
default) and further stating such other matters as Landlord shall reasonably
require.

        30.     Landlord's Lien. Tenant hereby grants to Landlord a lien and
security interest on all property of Tenant now or hereafter placed in or upon
the Premises, and such property shall be and remain subject to such lien and
security interest of Landlord for payment of all rent

-------------------
        (21) Landlord warrants, that as of the date of this Lease, Landlord
possesses the unencumbered fee simple title to the project.

                                       15
<PAGE>   19

and other sums agreed to be paid by Tenant herein.(22) The Provisions of this
paragraph relating to such lien and security interest shall constitute a
security agreement under and subject to Virginia Uniform Commercial Code so that
Landlord shall have and may enforce a security interest on all property of
Tenant now or hereafter placed in or on the Premises, in addition to and
cumulative of the Landlord's liens and rights provided by law or by the other
terms and provisions of this Lease. Tenant agrees to execute as debtors such
financing statement or statements as Landlord may now or hereafter request.
Landlord may at its election at any time file a copy of this Lease as a
financing statement. Notwithstanding the above, Landlord shall neither sell nor
withhold from Tenant, Tenant's business records.

        31.     Attorney's Fees. In the event either party defaults in the
performance of any of the terms of this Lease and the other party employs an
attorney in connection therewith, the defaulting party agrees to pay the
prevailing party's reasonable attorney's fees. In the event that Landlord
remedies a default by Tenant pursuant to Paragraph 26(b) (iii), Landlord shall
be entitled to reimbursement by Tenant on demand for all costs incurred in
connection with same (including without limitation attorney's fees), plus
interest thereon at the highest rate permitted by law.

        32.     No Implied Waiver. No provision of this Lease shall be deemed to
have been waived by Landlord unless such a waiver be in writing signed by
Landlord. The failure of Landlord to insist at any time upon the strict
performance of any covenant or agreement or to exercise any option, right, power
or remedy contained in this Lease shall not be construed as a waiver or a
relinquishment thereof for the future. No payment by Tenant or receipt by
Landlord of a lesser amount than the monthly installment of rent due under this
Lease shall be deemed to be other than on account of the earliest rent due
hereunder, nor shall any endorsement or statement on any check or any letter
accompanying any check or payment of rent be deemed an accord and satisfaction,
and Landlord may accept such check or payment without prejudice to Landlord's
right to recover the balance of such rent or pursue any other remedy in this
Lease provided. No agreement to accept a surrender of this Lease shall be valid
unless in a writing signed by Landlord. The receipt by Landlord of rent with
knowledge of the breach of any covenant of this Lease shall not be deemed a
waiver of such breach.

        33.     Personal Liability. The liability of Landlord to Tenant for any
default by Landlord under the terms of this Lease shall be limited to the
interest of Landlord in the Building and the land described on Exhibit "A"
attached hereto is situated and Tenant agrees to look solely to Landlord's
interest in the Building and the land on which the Building is situated for the
recovery of any judgement from the Landlord, it being intended that neither
Landlord nor any partner or principal of Landlord nor any other property
disclosed or undisclosed of such partners or principals shall be personally
liable for any judgement or deficiency.

---------------------

        (22) provided however, said lien shall be subordinate to the original
security interest if any, previously granted in the purchase of the property.

                                       16
<PAGE>   20

        34.     Security Deposit. The Security Deposit shall be held by Landlord
without liability for interest and as security for the performance by Tenant of
Tenant's covenants and obligations under this Lease, it being expressly
understood that the Security Deposit shall not be considered as advance payment
of rental or a measure of Tenant's damages in case of default by Tenant. Unless
otherwise provided by mandatory non-waivable law or regulation, Landlord may
commingle the Security Deposit with Landlord's other funds. Landlord may, from
time to time, without prejudice to any other remedy, use the Security Deposit to
the extent necessary to make good any arrearages of rent or to satisfy any other
covenant or obligation of Tenant hereunder. Following any such application of
the Security Deposit, Tenant shall pay to Landlord on demand the amount so
applied in order to restore the Security Deposit to its original amount. If
Tenant is not in default at the termination of this Lease, the balance of the
Security Deposit remaining after any such application shall be returned by
Landlord to Tenant. If Landlord transfers its interest in the Premises during
the term of this Lease, Landlord must assign the Security Deposit to the
transferee and thereafter shall have no further reliability for the return of
such Security Deposit.

        35.     Notice. Any notice in this Lease provided for must, unless
otherwise expressly provided herein, be in writing, and shall, unless otherwise
in this Lease expressly provided, be given or be served by depositing the same
in the United States mail, postpaid and certified, with return receipt required,
addressed to the party to be notified at the address stated in this Lease or
such other address notice of which has been given to the other party. Any notice
shall be effective upon its deposit in the United States mail in the manner
hereinabove described. Any responses by Tenant to Landlord upon any such notice
shall be given not later than five (5) business days following the date set
forth as the date of receipt on the return receipt. Copies of any Notice to
Landlord, shall also be served upon (i) Vice President, Real Estate Investments,
Northeastern office, Metropolitan Life Insurance Company, One Madison Avenue,
New York, New York, 10010 and (ii) Manager, Real Estate Investments, Suite 410,
1615 L Street, N.W., Washington D.C. 20036.

        36.     Severability. If any term of provision of this Lease, or the
application thereof to any person or circumstances shall, to any extent, be
invalid or unenforceable, the remainder of this Lease, or the application of
such term or provision to persons or circumstances other than those as to which
it is held invalid or unenforceable, shall not be affected thereby, and each
term and provision of this Lease shall be valid and enforceable to the fullest
extent permitted by law.

        37.     Recordation. Tenant agrees not to record this Lease or any
memorandum or copy thereof.

        38.     Governing Law. This Lease and the rights and obligations of the
parties hereto shall be interpreted, construed, and enforced in accordance with
the laws of the Commonwealth of Virginia.

                                       17
<PAGE>   21
       39.    Force Majeure. Whenever a period of time is herein prescribed for
the taking of any action by Landlord, Landlord shall not be liable or
responsible for, and there shall be excluded from the computation of such period
of time, any delays due to strikes, riots, acts of God, shortages of labor or
materials, war, governmental laws, regulations or restrictions, or any other
cause whatsoever beyond the control of Landlord.

       40.    Time of Performance. Except as expressly otherwise herein
provided, with respect to all required acts of Landlord and Tenant, time is of
the essence of this Lease.

       41.    Transfers by Landlord. Landlord shall have the right to transfer
and assign, in whole or in part, all its rights and obligations hereunder and in
the Building, Project and property referred to herein, and in such event and
upon such transfer Landlord shall be released from any further obligations
hereunder, and it shall be deemed and construed as a covenant running with the
land without further agreement between the parties or their successors in
interest, or between the parties and the transferee of the Building, or of the
land described in Exhibit "A" and the Building that the transferee has assumed
and agreed to carry out any and all covenants and obligations of Landlord
hereunder. Tenant agrees to look solely to such successor in interest of
Landlord for the performance of such obligations.

       42.    Commissions. Tenant hereby indemnifies and holds Landlord harmless
against any loss, claim, expense or liability with respect to any commissions
brokerage fees claimed on account of the execution and/or renewal of this Lease
due to any action of Tenant.

       43.    Effect of Delivery of This Lease. Landlord has delivered a copy of
this Lease to Tenant for Tenant's review only, and the delivery hereof does not
constitute an offer to Tenant or option. This Lease shall not be effective until
a copy executed by both Landlord and Tenant is delivered to and accepted by
Landlord.

       44.    Exhibits. Exhibits, "A", "B", "C", "D", "E", "F", "G", "H", "I",
"J", "L", "M", "N" and "O" are attached hereto and incorporated herein and made
a part of this Lease for all purposes.

       The parties acknowledge that the Tenant's name, Keyvan Rafei, has been
       misspelled as Keyvan Rafie in various references in this document, and
       agree that all such misspellings refer to the Tenant, Keyvan Rafei.

                                       18

<PAGE>   22

       IN WITNESS WHEREOF, Landlord and Tenant have executed this Lease in
multiple original counterparts as of the day and year first above written.

Address:                           LANDLORD: Met Life International
8300 Boone Boulevard               Real Estate Equity Share Inc., a
Suite 200                          Delaware Corporation
Vienna, VA 22182

                                   By:    MICHAEL J. CURRAN
                                          ----------------------------
                                          MICHAEL J. CURRAN

                                   Title: Assistant Vice President
                                          ----------------------------

                                   Date:           5\29\92
                                          ----------------------------

Address:                           TENANT: Keyvan Rafie, a sole proprietorship

                                   By:    KEYVAN RAFIE
                                          ----------------------------
                                          Keyvan Rafie

                                   Title: A Sole Proprietorship
                                          ----------------------------

                                   Date:           5-18-92
                                          ----------------------------

ATTEST:

Affix Seal:

                                       19

<PAGE>   23

                             AMERICAN CENTER LEASE
                                LIST OF EXHIBITS

This List of Exhibits is attached hereto and made a part of the Lease dated May
29, 1992, by and between AMERICAN CENTER ("Landlord") and Keyvan Rafie, a sole
proprietorship, ("Tenant").

EXHIBIT "A" - Description

EXHIBIT "B" - Outline Demised Premises

EXHIBIT "C" - Tenant Improvements (Workletter)

EXHIBIT "D" - Rental Escalation

EXHIBIT "E" - Rules & Regulations

EXHIBIT "F" - Parking Space Rental Agreement

EXHIBIT "G" - Termination Option

EXHIBIT "H" - Expansion Option

EXHIBIT "I" - Renewal Option

EXHIBIT "J" - Indemnity Agreement

EXHIBIT "L" - First Right of Refusal

EXHIBIT "M" - Furniture Inventory

EXHIBIT "N" - Signage

EXHIBIT "O" - Tenants Plans

<TABLE>
<S>                                            <C>
TENANT: Keyvan Rafie, sole proprietorship       LANDLORD: Met Life International Real
                                                Estate Equity Shares. Inc., a Delaware
                                                corporation

By:    KEYVAN RAFIE                             By:    MICHAEL J. CURRAN
     ------------------------                        --------------------------
       Keyvan Rafie                                    Michael J. Curran

Title: A Sole Proprietorship                    Title: Assistant Vice President
       ----------------------                          ------------------------

Date:    5-18-92                                Date:    5\29\92
    -------------------------                       ---------------------------
</TABLE>

<PAGE>   24

                                  EXHIBIT "A"

This Exhibit "A" is attached hereto and made a part of the Lease dated May 29,
1992, by and between Met Life International Real Estate Equity Shares, Inc.,
("Landlord") and Keyvan Rafie, a sole proprietorship ("Tenant").

All that certain lot, piece or parcel of land situate, lying and being in the
County of Fairfax, Virginia and being more particularly described as follows:

       Beginning at a point marking the intersection of the Southerly R/W line
       of Chain Bridge Road (Route # 123) and the Notheasterly R/W line of Boone
       Boulevard; thence with the said R/W line of Route 123 N 57 11' 27" E,
       77.04 feet with a curve to the right whose radius is 676.20 feet (and
       whose chord is N 64 45' 25" E, 202.58 feet) an arc distance of 203.35
       feet; N 73 22' 19" E, 34.26 feet; N 41 23' 12" W, 29.37 feet and N 73 22'
       19" E, 36.02 feet to a point; thence departing Chain Bridge Road and
       running with the Southerly R/W line of a ramp for an interchange from
       said Chain Bridge to Leesburg Pike (Route #7) the following courses: with
       a curve to the right whose radius is 200.00 feet (and whose chord is S 63
       34' 18" E, 97.06 feet) an arc distance of 98.04 feet with a curve to the
       left whose radius is 302.00 feet (and whose chord is N 87 49' 41' E.
       409.17 feet) an arc distance of 449.54 feet; N 45 11' 05" E, 48.58 feet
       and with a curve to the right whose radius is 100.00 feet (and whose
       chord is N 65 04' 50' E, 68.06 feet an arc distance of 69.45 feet to a
       point on the Southerly R/W line of Leesburg Pike (Route #7); thence with
       said R/W line of Leesburg Pike S 44 48' 55" E, 110.10 feet to a point
       marking the intersection of the said R/W line of Leesburg Pike and the
       Northwesterly R/W line of Howard Avenue; thence with the said R/W line of
       Howard Avenue S 44 49' 03" W, 552.21 feet to a point marking the PC of a
       30 foot radius return to the intersection of Howard Avenue on the
       aformentioned Boone Boulevard; thence with said return a curve to the
       right whose chord is S 80 39' 28" W, 35.13 feet, an arc distance of 37.53
       feet to a point on the aforementioned R/W line of Boone Boulevard; thence
       with the said R/W line of Boone Boulevard N 63 30' 09" W, 605.17 feet, to
       the point of the beginning containing 4.83879 acres of land.

<TABLE>
<S>                                             <C>
TENANT: Keyvan Rafie, a sole proprietorship     LANDLORD: Met Life International Real
                                                Estate Equity Shares, Inc., a Delaware
                                                corporation

By:       KEYVAN RAFIE                          By:       MICHAEL J. CURRAN
   ----------------------------------              ----------------------------------
          Keyvan Rafie                                    Michael J. Curran

Title:    A Sole Proprietorship                 Title:    Assistant Vice President
       ------------------------------                  ------------------------------

Date:           5-18-92                         Date:           5-29-92
     --------------------------------                --------------------------------
</TABLE>

<PAGE>   25

                                  EXHIBIT "B"

                                   [GRAPHIC]

This Exhibit "B" is attached hereto and made a part of the Lease dated May 29,
1992, by and between Met Life International Real Estate Equity Shares. Inc.,
("Landlord") and Keyvan Rafie, a sole proprietorship ("Tenant").

<TABLE>
<S>                                             <C>
TENANT: Keyvan Rafie, a sole proprietorship     LANDLORD: Met Life International Real
                                                Estate Equity Shares, Inc., a Delaware
                                                corporation

By:       KEYVAN RAFIE                          By:       MICHAEL J. CURRAN
   ----------------------------------              ----------------------------------
          Keyvan Rafie                                    Michael J. Curran

Title:    A Sole Proprietorship                 Title:    Assistant Vice President
       ------------------------------                  ------------------------------

Date:           5-18-92                         Date:           5-29-92
     --------------------------------                --------------------------------
</TABLE>
<PAGE>   26

                                   EXHIBIT "C"

This Exhibit "C" is attached hereto and made a part of the Lease dated May 29,
1992, by and between Met Life International Real Estate Equity Shares, Inc.,
("Landlord") and Keyvan Rafie, a sole proprietorship, ("Tenant").

Landlord, at its expense, shall prepare a plan or sets of plans (which said plan
or sets of plans, as the case may be, is hereinafter called the "Tenant
Drawings") including dimensions necessary to construct and finish the demised
premises. In accordance with the Tenant Drawings dated 4-23-92, Landlord, at
Landlord's expense, except as otherwise expressly specified in this Exhibit "C"
and in the foregoing Lease shall furnish, install in and to the demised premises
the following, all of which shall be material, manufacture, design, capacity,
finish and color of the Building Standard adopted by Landlord for the Building:

1.     PARTITIONING:

       (a)    Drywall partitions consisting of 5/8" thickness on each side taped
              and sanded to the underside of the ceiling.

       (b)    Partitions terminating at the Building exterior walls shall meet
              either a mullion or column without interfering with access to the
              peripheral enclosure.

       (c)    Demising partitions consisting of 5/8" thickness on each side
              taped and sanded to the underside of the ceiling. Walls shall be
              insulated.

2.     DOORS AND HARDWARE:

       (a)    Suite entry door will be full height solid core, 8'4" x 3'0"
              laminate wood grain veneer finish entrance door, installed in an
              anodized aluminum frame, equipped with exposed closer, with a
              l'0" sidelight.

              All doors off the common hallways shall have heavy duty lever
              handle lockset with closer.

              All interior doors will be flush, solid core, "laminate, wood
              grain veneer" full height 8'4" x 3'0" installed in an anodized
              aluminum frame with a latch-set.

3.     CEILINGS:

       (a)    Tegular acoustical tile, 2' x 2' on an exposed grid mounting
              system installed throughout.

4.     FLOOR COVERING AND BASE MOLDING:

       (a)    Tenant will be allowed up to $1.00 per square foot of leased area
              for carpeting, vinyl base and padding or Tenant may select from
              Landlord's building standard carpet selections, building standard
              carpet padding is provided by Landlord.

<PAGE>   27

5.     ELECTRICAL:

       (a)    Single pole light switches.

       (b)    120 volt duplex wall receptacle outlets.

6.     TELEPHONE:

       (a)    Building Standard wall telephone outlet with ring and pull string.

7.     WINDOW COVERING:

       (a)    Landlord shall provide Building Standard thin line horizontal
              venetian blinds on all exterior windows.

8.     PAINTING:

       (a)    Partitions and walls shall be finished with flat latex paint.
              Painting shall be in colors to be selected by Tenant from
              Landlord's Building Standard color chart, not to exceed one color
              per room.

9.     LIGHTING:

       (a)    Recessed three (3) tube 2' x 4' Parabolic Building Standard
              fluorescent light fixtures.

10.    ENTRANCE DOOR LETTERING:

       (a)    The Landlord shall provide the suite number and Tenant's name
              (excluding logos or names of individual officers and/or partners,
              other than the actual firm name) using Landlord's Building
              Standard character Building Logo.

11.    HEATING/VENTILATION AND AIR CONDITIONING:

       (a)    Landlord will provide Building Standard heating, cooling and
              circulating air equipment and controls for normal office use. The
              system shall be all electric, operated and maintained by Landlord
              at Landlord's expense.

       (b)    Any excess capacity, special controls, or exhaust required by
              Tenant shall be provided by Landlord at Tenant's expense.

       (c)    Capability for after hours air conditioning will be provided for
              by Landlord. Expense for after hours use shall be Tenant's.

<PAGE>   28

12.    SPACE PLANNING:

       (a)    Up to two (2) preliminary architectural Tenant drawings will be
              provided by the Landlord's selected architect or design firm at
              Landlord's expense.

       (b)    Any additional preliminary drawings or any sections, elevations or
              details or any specifications of non-Building Standard work shall
              be at Tenant's expense.

It is agreed that the Tenant will furnish to the Landlord all information
regarding its partitioning, electrical, mechanical and telephone requirements
and all other pertinent data by not later than June 15, 1992. Within five (5)
days after Landlord's submission of working drawings, the Tenant shall approve
of said drawings in writing. In the event Tenant fails to comply with either of
the aforesaid time requirements, any delay in completing the demised premises
shall not in any manner affect the Commencement Date as provided in the
foregoing Lease, under such circumstances Landlord agrees to make the demised
premises ready for Tenant's occupancy not later than the Commencement Date,
plus the number of days resulting from Tenant's failure to comply with the
provisions of this paragraph.

If Tenant requests any additional work which is not provided for in the
aforesaid "Building Standard Tenant Allowances", Tenant will be responsible for
all costs resulting from such additional work, including architectural and
engineering charges, which costs shall be paid by Tenant on or before occupancy
of the demised premises. Tenant understands that no credits will be given for
any portion of the allowances specified above which are not required by Tenant.

If there are any changes requested by Tenant, after completion of Tenant
Drawings, Tenant will be responsible for all architectural and engineering costs
and related expenses resulting from such changes. No such changes will be made
without written approval of the Landlord and only after written request of the
Tenant to the Landlord.

Tenant agrees to pay to Landlord, promptly upon being billed therefore, the cost
of all such work, together with ten percent (10%) overhead, and ten percent
(10%) profit on such costs. Tenant will be billed for seventy-five percent (75%)
of said costs on such non-standard or additional work at the commencement of
construction of the space and twenty-five percent (25%) when work is complete,
as determined by Landlord's architect, engineer and/or contractor.

TENANT: Keyvan Rafie, a                   LANDLORD: Met Life International Real
sole proprietorship                       Estate Equity Shares, Inc., a Delaware
                                          corporation

By: /s/ KEYVAN RAFIE                      By: /s/ MICHAEL J. CURRAN
   -------------------------------           -------------------------------
       Keyvan Rafie                                            Michael J. Curran
Title: A Sole Proprietorship              Title: Assistant Vice President
      ----------------------------              ----------------------------

Date:     5-18-92                         Date:         5/29/92
     -----------------------------             -----------------------------

<PAGE>   29

                                   EXHIBIT "D"

This Exhibit "D" is attached hereto and made a part of the Lease dated May 29,
1992, by and between Met Life International Real Estate Equity Shares, Inc.,
("Landlord") and Keyvan Rafie, a sole proprietorship ("Tenant").

          1.  Basic Cost Increase Adjustment. The Base Rental payable hereunder
       shall be adjusted from time to time in accordance with the following
       provisions:

              (a) The Building contains 324,668 square feet of Net Rentable Area
       in aggregate. Tenant's Base Rental is based, in part, upon the estimate
       that annual Basic Costs will be equal to $7.75 per square foot of Net
       Rentable Area in the Building (such estimate being hereinafter referred
       to as the "Expense Stop"). Tenant shall, when Landlord so requires during
       the term of this lease, pay as an adjustment to Base Rental hereunder,
       regardless of rental abatement, an amount (per each square foot of Net
       Rentable Area within the Premises, including those portions of Common
       Areas allocated to the Premises from time to time) equal to the excess
       ("Excess") from time to time of actual Basic Costs per square foot of Net
       Rentable Area in the Building over the amount of the Expense Stop.
       Landlord may collect such additional Base Rental in arrears. Landlord
       shall also have the option to make a good faith estimate of the Excess
       for each upcoming calendar year and may require the monthly payment of
       Base Rental adjusted in accordance with such estimate. Any amounts paid
       based on such an estimate shall be subject to adjustments pursuant to
       Paragraph 1(b) of this Exhibit "D" when actual Basic Costs are available
       for each calendar year.(1)

              (b) Tenant at its' expense shall have the right no more frequently
       than once per calendar year, following prior written notice to Landlord,
       to audit through an independent certified public accountant reasonably
       acceptable to Landlord, at Tenant's sole expense, Landlord's books and
       records relating to Basic Costs during the year preceding such audit. In
       the event such an audit demonstrates additional Base Rental collected for
       such preceding year to be higher or lower than the amount of additional
       rental paid pursuant to 1(a) above, then Landlord shall refund any
       overpayment or Tenant shall pay any deficiency within ten (10) days of
       such determination.

       ---------------------

          (1) Notwithstanding the foregoing, the amount of any excess payable by
       Tenant relating to Basic Costs other than property taxes and assessments
       and utility costs shall not in any event increase by greater than six
       percent (6%) per year.

<PAGE>   30

          2.  "Basic Costs" shall mean all direct and indirect costs and
       expenses in each calendar year of operating, maintaining, repairing,
       managing and owning (including without limitation, property taxes and
       assessments) the Building and the Exterior Common Area (as defined in the
       Lease to which this is Exhibit "D"). Basic Costs shall not include the
       cost of any capital improvements, depreciation, interest on principal
       payments on mortgage and other non-operating debts,(2) of Landlord. Basic
       Costs shall, however, include the amortization of capital improvements
       which are primarily for the purpose of reducing Basic Costs, or which are
       required by governmental authorities.

          3.  Base Rental Adjustment. Effective the first day following the
       expiration of each twelve (12) month period during the Lease Term, the
       Base Rental shall be adjusted as follows: Successive yearly base rates
       are one hundred four and one half percent (104.5%) of the previous year's
       Base Rental. Landlord shall be entitled to require that the payment of
       the adjustment to Base Rental provided for in this paragraph, be made in
       monthly installments equal to 1/12 of such adjustment for each year
       during the remainder of the Lease Term, such installments being due and
       payable on the first day of each calendar month during such Year. The
       Expense Stop initially stated in paragraph 1(a) hereof shall be utilized
       throughout the term of this Lease for the purpose of calculating the
       Excess pursuant to Paragraph 1(a) notwithstanding any adjustment to Base
       Rental pursuant to this paragraph.

TENANT:  Keyvan Rafie, a                  LANDLORD: Met Life International Real
sole proprietorship                       Estate Equity Shares. Inc., a Delaware
                                          corporation

By: /s/ KEYVAN RAFIE                      By: /s/ MICHAEL J. CURRAN
   -------------------------------           -------------------------------
       Keyvan Rafie                              Michael J. Curran
Title: A Sole Proprietorship              Title: Assistant Vice President
      ----------------------------               ---------------------------

Date:     5-18-92                         Date:         5/29/92
     -----------------------------             -----------------------------

       ---------------------

          (2) Marketing, other tenant improvements and leasing expenses.

<PAGE>   31

                                   EXHIBIT "E"

This Exhibit "E" is attached hereto and made a part of the Lease dated May 29
1992, by and between Met Life International Real Estate Equity Shares, Inc.,
("Landlord") and Keyvan Rafei, a sole proprietorship ("Tenant").

                              RULES AND REGULATIONS

1.     Sidewalks, doorways, vestibules, halls, stairways, and similar areas
       shall not be obstructed nor shall refuse, furniture, boxes or other items
       be placed therein by Tenant or its officers, agents, servants, and
       employees, or used for any purpose other than ingress and egress to and
       from the leased premises, or for going from one part of the Building to
       another part of the Building. Canvassing, soliciting and peddling in the
       Project are prohibited.

2.     Plumbing fixtures and appliances shall be used only for the purposes for
       which constructed, and no unsuitable material shall be placed therein.

3.     No signs, directories, posters, advertisements, or notices shall be
       painted or affixed on or to any of the windows or doors, or in corridors
       or other common areas of the Building, except in such color, size, and
       style, and in such places, as shall be first approved in writing by
       Landlord in its reasonable discretion. One building standard suite
       identification sign will be prepared by Landlord at Landlord's expense.
       No additional signs shall be posted without Landlord's prior written
       consent as to location and form, and the cost of preparing and posting
       such signs shall be borne solely by Tenant. Landlord shall have the right
       to remove all unapproved signs without notice to Tenant, at the expense
       of Tenant.

4.     Tenants shall not do, or permit anything to be done in or about the
       Building, or bring or keep anything therein, that will in any way
       increase the rate of fire or other insurance on the Building, or on
       property kept therein or otherwise increase the possibility of fire or
       other casualty.

5.     Landlord shall have the power to prescribe the weight and position of
       heavy equipment or objects which may overstress any portion of the floor.
       All damage done to the Building by the improper placing of such heavy
       items will be repaired at the sole expense of the responsible Tenant.

6.     Tenant shall notify the Building manager when safes or other heavy
       equipment are to be taken in or out of the Building, and the moving shall
       be done after written permission is obtained from Landlord on such
       conditions as Landlord shall require. Any moving in or moving out of
       Tenant equipment, furniture, files, and/or fixtures shall be done only
       with prior written notice to Landlord, and Landlord shall be entitled to
       prescribe the hours of such activity, the elevators which shall be
       available for such activity and shall, in addition, be entitled to place
       such other reasonable conditions upon Tenant moving activities as
       Landlord deems appropriate. Tenant shall bear all risk of loss relating
       to damage incurred with respect to Tenant's property in the process of
       such a move, and in addition, shall indemnify and hold Landlord harmless
       as to all losses, damages, claims, causes of action, costs and/or
       expenses relating to personal injury or property damage sustained by
       Landlord or any third party on account of Tenant moving activities.

7.     Corridor doors, when not in use, shall be kept closed.

<PAGE>   32
8.     All deliveries must be made via the service entrance and elevators,
       designated by Landlord for service, if any, during Normal Business Hours.
       Landlord's written approval must be obtained for any delivery after
       normal working hours.

9.     Each tenant shall cooperate with Landlord's employees in keeping leased
       premises neat and clean.

10.    Tenant shall not cause or permit any improper noises in the Building, or
       allow any unpleasant odors to emanate from the leased premises, or
       otherwise unreasonably interfere, injure or annoy in any way other
       tenants, or persons having business with them.

11.    No animals shall be brought into or kept in or about the Building.

12.    No boxes, crates or other such materials shall be stored in hallways or
       other Common Areas. When Tenant must dispose of crates, boxes, etc. it
       will be the responsibility of Tenant to dispose of same prior to, or
       after the hours of 7:30 a.m. and 5:30 p.m., respectively, so as to avoid
       having such debris visible in the Common Areas during Normal Business
       Hours.

13.    No machinery of any kind, other than ordinary office machines such as
       typewriters, calculators, and standard office equipment shall be operated
       on leased premises without the prior written consent of Landlord, nor
       shall a tenant use or keep in the Building any flammable or explosive
       fluid or substance (including Christmas trees and ornaments), or any
       illuminating materials, except candles. No space heaters or fans shall be
       operated in the Building.

14.    No bicycles, motorcycles or similar vehicles will be allowed in the
       Building.

15.    No nails, hooks or screws shall be driven into or inserted in any part of
       the Building except picture frames and as otherwise approved by Building
       maintenance personnel. Nothing shall be affixed to, or made to hang from
       the ceiling of the Premises without Landlord's prior written consent.

16.    Landlord has the right to evacuate the Building in the event of an
       emergency or catastrophe.

17.    No food and/or beverages shall be distributed from Tenant's office
       without prior written approval of the Building Manager.

18.    No additional locks shall be placed upon any doors without the prior
       written consent of the Landlord.

       All necessary keys shall be furnished by Landlord, and the same shall be
       surrendered upon termination of this lease, and Tenant shall then give
       Landlord or his agent an explanation of the combination of all locks on
       the doors or vaults. Tenant shall initially be given ten (10) keys to the
       Premises by Landlord. No duplicates of such keys shall be made by Tenant.
       Additional keys shall be obtained only from Landlord, at a fee to be
       determined by Landlord.
<PAGE>   33

19.    Tenant will not locate furnishings or cabinets adjacent to mechanical or
       electrical access panels so as to prevent operating personnel from
       servicing such units as routine or emergency access may require. Cost of
       moving such furnishings for Landlord's access will be for Tenant's
       account. The lighting and air conditioning equipment of the Building will
       remain the exclusive charge of the Building designated personnel.

20.    Tenant shall comply with parking rules and regulations as may be posted
       and distributed from time to time.

21.    No portion of the Building shall be used for the purpose of lodging
       rooms.

22.    Vending machines or dispensing machines of any kind will not be placed in
       the leased premises by Tenant.

23.    Prior written approval, which shall be at Landlord's sole discretion,
       must be obtained for installation of window shades, blinds, drapes, or
       any other window treatment of any kind whatsoever. Which approval will
       not be unreasonably withheld. Landlord will control all internal lighting
       that may be visible from the exterior of the Building and shall have the
       right to change any unapproved lighting, without notice to Tenant, at
       Tenant's expense.

24.    No Tenant shall make any material changes or alterations to any portion
       of the Building without Landlord's prior written approval, which may be
       given on such conditions as Landlord may elect which shall not be
       unreasonable. All such work shall be done by Landlord or by contractors
       and/or workmen approved by Landlord, working under Landlord's
       supervision.

25.    Landlord reserves the right to rescind any of these rules and make such
       other and further reasonable rules and regulations as in its reasonable
       judgment shall from time to time be needful for the subject to operation
       of the Building subject to the terms of this Lease, which rules shall be
       binding upon each Tenant upon delivery to such Tenant of notice thereof
       in writing.

<TABLE>
<S>                                       <C>
TENANT: Keyvan Rafie, a                    LANDLORD: Met Life International Real
sole proprietorship                        Estate Equity Shares, Inc., a Delaware
                                           corporation

By: /s/ KEYVAN RAFIE                       By: /s/ MICHAEL J. CURRAN      GG
   -------------------------                  -------------------------------
        Keyvan Rafie                               Michael J. Curran

Title: A Sole Proprietorship               Title: Assistant Vice President
      ----------------------                     ----------------------------

Date:      5-18-92                         Date:          5/29/92
     -----------------------                    -----------------------------
</TABLE>

<PAGE>   34

                                   EXHIBIT "F"

This Exhibit "F" is attached hereto and made a part of the Lease dated
May 29, 1992 by and between Met Life International Real Estate Equity
Shares, Inc., ("Landlord") and Keyvan Rafie, a sole proprietorship, ("Tenant").

                         PARKING SPACE RENTAL AGREEMENT

       This Agreement is made and entered into by and between MET LIFE
INTERNATIONAL REAL ESTATE EQUITY SHARES, INC., a Delaware corporation (herein
"Landlord") and Keyvan Rafie, a sole proprietorship, (herein "Tenant").

RECITALS:

       A.     Landlord is "Landlord" and Tenant is "Tenant" under that certain
Lease Agreement (the "Lease") dated May 29, 1992 wherein Tenant leased from
Landlord certain premises (the "Premises") located in Landlord's office building
(the "Building") at 8330 Boone Boulevard, Vienna, Virginia, 22182.

       B.     Landlord desires to grant and Tenant desires to acquire the right
to use certain of the Building's parking spaces.

       NOW, THEREFORE, for and in consideration of Ten and No/l00 Dollars,
($10.00) and other valuable consideration, the receipt and sufficiency of which
are hereby acknowledged, the parties hereto hereby agree as follows:

       1.     Landlord hereby grants Tenant license to use seventy-six (76)
parking spaces (the "Parking Spaces") located in the Building garage at no
additional expense to Tenant for the initial term of this Lease, for the purpose
of parking motor vehicles for a term commencing on July 1, 1992 and terminating
upon termination or expiration of the Lease for whatever reason.

       2.     In addition, Landlord hereby grants Tenant license to use fourteen
(14) parking spaces (the "Parking Spaces") located in the Building garage for
the initial term of this Lease, for the purpose of parking motor vehicles for a
term commencing on July 1, 1992 and terminating upon termination or expiration
of the Lease for whatever reason. Tenant hereby agrees to pay an initial rental
fee of $25.00 per month for each of the Parking Spaces, which fee shall be
payable monthly in advance on or before the first day of each month throughout
the initial term of the Lease.

       3.     All motor vehicles (including all contents thereof) shall be
parked in all spaces leased hereunder at the sole risk of the owner thereof, it
being expressly agreed and understood that Landlord has no duty to insure any of
said motor vehicles (including the contents thereof), and that Landlord is not
responsible for the protection and/or security of such vehicles. Landlord shall
have no liability whatsoever to Tenant for any

-----------------

       (3) Two (2) of the seventy six (76) parking spaces shall be reserved for
"Rafie & Associates".

<PAGE>   35

property damage and/or personal injury which might occur as a result of or in
connection with the parking of said motor vehicles in any of said spaces, and
Tenant hereby agrees to indemnify and hold Landlord harmless from and against
any and all costs, claims, expenses, and/or causes of action (including
reasonable attorney's fees) which Landlord may incur in connection with or
arising out of Tenant's use of said spaces pursuant to this Agreement.

       4.     It is further agreed that this Agreement shall not be deemed to
create a bailment between the parties hereto, it being expressly agreed and
understood that the only relationship created between Landlord and Tenant hereby
is that of licensor and licensee, respectively.

       5.     In it's use of the spaces, Tenant shall follow all of the rules of
the Building applicable thereto, as the same may be reasonably amended from time
to time. Upon the occurrence of any breach of such rules, or default by Tenant
pursuant to Section 26 of this Lease, or under this Agreement, Landlord shall be
entitled to terminate this Agreement, in which event Tenant's right to utilize
any and all of the spaces leased hereunder shall thereupon cease.

       6.     In the event of substantial casualty damage to the parking garage
located within the Project (the "Garage") which in accordance with Section 23 of
this Lease makes it impossible or impractical for Landlord economically to
comply with this Agreement, this license shall terminate upon and as of the
date of such casualty. If the Garage (or a portion thereof) or any part of the
real property upon which the Garage is situated is taken by governmental or
quasi-governmental action or sale in lieu thereof and such taking or sale makes
it impractical or impossible for Landlord economically to comply with this
Agreement, this Agreement shall terminate as of the date of such taking or sale.

       7.     To further insure that only those parties leasing Parking Spaces
are utilizing such parking spaces, Tenant shall provide Landlord with a complete
list of the names of all of Tenant's employees issued security access cards,
which list shall contain the corresponding license plate numbers of those
automobiles owned, leased or used by each of said employees. Such list shall be
updated by Tenant periodically, as necessary, and shall contain a specific
designation as to which automobiles of which employees have been issued decals
for Parking Spaces. Tenant hereby agrees to pay all amounts falling due
hereunder upon demand therefore, and the failure to pay any such amount shall
additionally be deemed an event of default under the Lease, entitling Landlord
to all of its right and remedies thereunder.

TENANT: Keyvan Rafie, a              LANDLORD: Met Life International Real
sole proprietorship                  Estate Equity Shares, Inc., a Delaware
                                     corporation

By: /s/ KEYVAN RAFIE                 By: /s/ MICHAEL J. CURRAN         GG
   --------------------------            ---------------------------------
        Keyvan Rafie                             Michael J. Curran

Title: A Sole Proprietorship        Title: Assistant Vice President
      -----------------------              -------------------------------

Date:       5-18-92                 Date:          5/29/92
     ------------------------              -------------------------------

<PAGE>   36
                                   EXHIBIT "G"

                               TERMINATION OPTION

Tenant shall have the one (1) time option to terminate this Lease on the last
day of the ninety-sixth (96th) month of the Lease Term provided that (i) Tenant
is not then nor has ever been in material default of any of the terms and
conditions under this Lease, (ii) Tenant provides Landlord with at least two
hundred seventy (270) days prior written notice of such termination, and (iii)
Tenant shall pay a cash termination fee equal to $300,000.00 (representing
unamortized costs (i.e., above standard improvements, commissions and rental
concessions)) submitted with written notice. In the event Tenant is not in
default of any of the obligations of this Lease and Tenant does not exercise
this Option to Terminate under the terms and conditions mentioned above,
Tenant's lease shall remain in full force for the remainder of the Lease Term.

<TABLE>
<S>                                        <C>
TENANT: Keyvan Rafie, a                     LANDORD: Met Life International Real
sole proprietorship                         Estate Equity Shares, Inc., a Delaware
                                            corporation

By: /s/ KEYVAN RAFIE                        By /s/ MICHAEL J. CURRAN       GG
    -----------------------------              ---------------------------------
            Keyvan Rafie                               Michael J. Curran

Title: A Sole Proprietorship                Title: Assistant Vice President
      ---------------------------                 ------------------------------

Date:        5-18-92                        Date:         5/29/92
     ----------------------------                -------------------------------
</TABLE>

<PAGE>   37
                                   EXHIBIT "H"

                                 EXPANSION SPACE

Tenant shall have the following rights to lease additional space in the
Building, subject to the following term and conditions:

1.     The Expansion Space

       (A)    Tenant shall have the right to lease a block of approximately
5,000 s.f. square feet [plus or minus twenty percent (20%)] of Net Rentable Area
in the Building ("The Expansion Space"). The Expansion Space shall be made
available to Tenant no earlier than the first day of the forty-eighth (48th)
month of the Lease Term and no later than the last day of the seventy-second
(72nd) month of the Lease Term. On or before the first day of the thirty-sixth
(36th) month of the Lease Term, Landlord shall provide Tenant with a written
notice stating: (i) the exact location of The Expansion Space (to be
cross-hatched on a floor plan of the Building); (ii) the exact Net Rentable Area
of The Expansion Space that will be available; and (iii) the date during The
Expansion Period that The Expansion Space will be available for Tenant's
occupancy ("The Expansion Space Availability Date"). Tenant shall provide
Landlord with written notice of its election to exercise this option, or its
rejection thereof, at least nine (9) months prior to The Expansion Space
Availability Date. Tenant hereby agrees that it will act reasonably with respect
to Landlord's ability to deliver the exact square footage described above for
The Expansion Space.

       (B)    The annual base rental payable for The Expansion Space shall be at
the prevailing market rate of comparable space in the building as of The
Expansion Space Availability Date.

       (C)    Within seven (7) days following Tenant's exercise of its option to
lease The Expansion Space, Landlord and Tenant shall execute an amendment ("The
Amendment") to this Lease incorporating The Expansion Space into the Premises,
and setting forth the provisions contained in Subparagraph 1(B) above. Tenant's
failure to execute The Amendment within such seven (7) day period for any reason
other than Landlord's failure to provide such Amendment to Tenant, shall
constitute a waiver of the option granted in this Section 1.

<PAGE>   38

2.     Improvements

       In the event Tenant's Expansion Space has either: (i) never been built
out; or (ii) demolished for whatever reason, the Landlord shall provide Tenant
a Building Standard work letter consistent with Exhibit "C" attached hereto. In
the event Tenant's Expansion Space has been previously built out for office use,
then Tenant shall accept said Expansion Space in it's present "as is" condition.

<TABLE>
<S>                                        <C>
TENANT: Keyvan Rafie, a                     LANDLORD: Met Life International Real
sole proprietorship                         Estate Equity Shares, Inc., a Delaware
                                            corporation

By: /s/ Keyvan Rafie                        By: /s/ Michael J. Curran         GG
    ------------------------                    --------------------------------
         Keyvan Rafie                                  Michael J. Curran

Title: A Sole Proprietorship                Title: Assistant Vice President
       ---------------------                      ------------------------------

Date:       5-18-92                         Date:       5/29/92
      ----------------------                     -------------------------------
</TABLE>

<PAGE>   39

                                   EXHIBIT "I"

                                 RENEWAL OPTION

Tenant shall have the following option (the "Option") to renew this Lease:

Tenant may, by notifying Landlord of it's election in writing at least twelve
(12) months prior to the end of the Lease Term, renew this Lease for an
additional lease term (the "Second Lease Term") beginning on the day next
following the expiration date of the Lease Term and continuing for five (5)
years thereafter. Such renewal shall be on all of the terms and conditions of
this Lease which are not inconsistent herewith, except that the rentals payable
during the Second Lease Term shall be at the then prevailing market rental rate
of comparable space within the Building as of the date of renewals, less five
percent (5 %). In no event, however, shall the rental rate for the Second Lease
Term be less than the rental rate for the Initial Lease Term.

Failure by Tenant to notify Landlord of Tenant's election to exercise this
renewal option herein granted within the time limited set forth for such
exercise shall constitute a waiver of such Option.

For the purposes of determining the prevailing market rate of the Premises (the
"Market Rate") for the renewal terms, Landlord and Tenant agree to the following
procedure:

       (i)    The Market Rate shall be determined by Landlord and Tenant during
the period of the first three months following Tenant's notice to Landlord that
Tenant elects to exercise its option to extend the Lease for a renewal term; and

       (ii)   In the event Landlord and Tenant are unable to agree upon the
Market Rate of the Premises during said three month period; then the same shall
be determined by arbitration in the following manner:

              FIRST: Landlord and Tenant shall each appoint a fit and impartial
       person as arbiter who shall have had at least ten (10) years of
       experience in the County Fairfax in a calling connected with the subject
       matter of the dispute. Such appointment shall be signified in writing by
       each party to the other, and the arbiters so appointed, in the event of
       their failure to agree within thirty (30) days upon the matter so
       submitted, shall appoint an umpire.

              SECOND: In the case of failure of such arbiters to agree and their
       failure to agree upon an umpire, then such umpire shall be appointed by
       the American Arbitration Association from its qualified panel of
       arbitrators, and shall be a person having at least ten (10) years
       experience as to the subject matter in question.

              THIRD: In case either Landlord or Tenant shall fail to appoint an
       arbiter, as aforesaid, within a person of twenty (20) days after written
       notice from the other party to make such appointment, than the arbiter
       appointed by the party no in default hereunder shall appoint a second
       arbiter and the two so appointed shall, in the event of their failure to
       agree upon a decision within ten (10) days thereafter, appoint an umpire.

<PAGE>   40

              FOURTH: The arbiters and umpire, after being duly sworn to perform
       their duties with impartiality and fidelity, shall proceed with all
       reasonable dispatch to determine the questions submitted. The decision of
       the arbiters and umpire, as the case may be, shall in any event be
       rendered within thirty (30) days after their appointment, and such
       decision shall be in writing and in duplicate, one counterpart thereof to
       be delivered to each of the parties.

              FIFTH: The arbitration shall be conducted in accordance with the
       rules of the American Arbitration Association, and the award of the
       arbitrators shall be binding, final and conclusive on the parties. The
       fees of the arbiters and umpire and the expenses incident to the
       proceedings shall be borne equally between Landlord and Tenant. The fees
       of respective counsel engaged by the parties, and the fees of expert
       witnesses and other witnesses called for by the parties shall be paid by
       the respective party engaging such counsel or calling or engaging such
       witnesses.

              SIXTH: The arbiters and umpire, as the case may be, shall have not
       authority to modify, change or amend any of the terms, covenants and
       conditions of this Lease, and shall be limited to making a determination
       of the then Market Rate of the Premises.

TENANT: Keyvan Rafie, a                   LANDLORD: Met Life International Real
sole proprietorship                       Estate Equity Shares, Inc., a Delaware
                                          corporation

By: /s/ KEYVAN RAFIE                      By: /s/ MICHAEL J. CURRAN       GG
   -------------------------------           -------------------------------
        Keyvan Rafie                             Michael J. Curran
Title:  A Sole Proprietorship             Title: Assistant Vice President
      ----------------------------               ---------------------------

Date:     5-18-92                         Date:         5/29/92
     -----------------------------             -----------------------------

<PAGE>   41

                                   EXHIBIT "J"

                               INDEMNITY AGREEMENT

THIS INDEMNITY AGREEMENT (this "Agreement") is made as of the 29th day of May,
l992 by and between MET LIFE INTERNATIONAL REAL ESTATE EQUITY SHARES, INC., a
Delaware corporation ("Landlord"), and KEYVAN RAFIE, a sole proprietorship
("Tenant").

                                    Recitals:

R-1. Landlord, as landlord, and Tenant, as tenant, have entered into a certain
lease (the "Lease") dated of even date herewith covering certain premises more
particularly described in Exhibit "B" of the Lease in the building located at
8330 Boone Boulevard, Vienna, in Fairfax, Virginia.

R-2. Tenant is currently party as tenant to that certain office Lease (also
referred to in said Office Lease as the "Standard Office Lease" and the
"Agreement of Lease", but herein referred to as the Tycon Lease) dated the 30th
day of November 1987, by and between Tenant and J.T.L. Tycon Towers I Limited
Partnership ("J.T.L."), a Virginia Limited Partnership, as landlord, covering
premises (the "Tycon Premises") known as Suite 1300 in the building located at
8000 Towers Crescent Drive, Vienna, Virginia, as amended by Lease Addendum dated
the 30th day of November, 1987.

R-3. To induce Tenant to enter into the Lease, Landlord has agreed to indemnify
Tenant from liability for monthly rent and its proportionate share of operating
costs and expenses under the Tycon Lease from and after the later to occur (the
"Indemnity Commencement Date") of (i) the commencement date of the Lease or (ii)
the date Tenant vacates the Tycon Premises, subject to the terms and conditions
of this Agreement.

R-4. The parties desire to enter into this Agreement to set forth their
respective rights and obligations with respect to the Tycon Lease.

NOW, THEREFORE, in consideration of the premises, the mutual covenants and
agreements of the parties, and for other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, the parties undertake
as follows:

                                   Agreement:

1.     Recitals. The foregoing Recitals are a material part of this Agreement
and are incorporated herein by reference.

2.     Indemnity. Subject to compliance by Tenant with all of its obligations
under this Agreement and the Lease, Landlord hereby indemnifies and holds
harmless Tenant from and against its obligations under the Tycon Lease, coming
due subsequent to the Indemnity Commencement Date, to pay the monthly rent and
the Tenant's proportionate share of operating costs and expenses under the Tycon
Lease, less the amount of any payments made by any subtenant or assignee on
account of such rent or other charges. Notwithstanding that Landlord may from
time to time make payments of rent due under the Tycon Lease directly to J.T.L.
on behalf of Tenant, such payments shall not be construed, nor shall the same be
deemed, as an assumption of, nor of Landlord's intent or desire to assume, nor
as an acceptance of an assignment by Tenant of, the Tycon Lease.

<PAGE>   42

3.     Management Agent.

       (a)    Tenant hereby appoints Landlord as Tenant's agent for the purpose
of locating and entering into subleases or assignments of all or portions of the
Tycon Premises, and for the purposes of acting as Tenant's managing agent for
the collection of sub-rents and other payments due under any subleases and
assignments enforcement of subleases and assignments, and taking such action as
may be necessary under any sublease or assignment in furtherance of performance
hereunder. Landlord hereby accepts such appointment.

       (b)    Upon request by Landlord, Tenant shall provide written notice to
J.T.L. and its managing agent of the appointment by Tenant of Landlord as its
agent for the purposes described herein.

       (c)    It is the intent of the parties that Landlord shall have the right
to manage and control the Tycon Premises and the subleasing and assignment
thereof, and have full and complete information with respect to such premises
and their use and occupancy, in order that Landlord shall have all opportunity
to mitigate and control its indemnity obligations. Any action or omission by
Tenant which is inconsistent with such intent (including without limitation
direct dealings with any subleases or assignee without Landlord's approval, or
termination of this agency) shall upon five (5) business days written notice
discharge Landlord from its obligations under this Agreement.

4.     Condition of Premises. Until the commencement date of the Lease, Tenant
will maintain the Tycon Premises in a good and orderly condition, in compliance
with all terms of the Tycon Lease, and shall not remove therefrom any bathroom
fixtures, lighting fixtures, finishes, millwork, floor covering and similar
items, without the prior written consent of Landlord, which consent may be
granted or withheld by Landlord in its discretion. As soon as is reasonably
possible after the commencement date of the Lease, Tenant will vacate the Tycon
Premises, leaving the same vacant or Tenant's personal property and equipment,
in broom-clean condition, and in condition suitable for showing to prospective
subtenants or assignees thereof.

5.     Cooperation.

       (a)    Tenant shall cooperate with and assist Landlord in effecting an
assignment of subletting of all or portions of the Tycon Premises to assignee(s)
or subtenant(s) identified by Landlord, including without limitation, assistance
in obtaining such consents as may be necessary from J.T.L., its agents,
successors or assigns, and providing access for the purpose of showing the Tycon
Premises to prospective assignees and subtenants.

       (b)    Within five (5) business days after request therefor by Landlord,
Tenant shall execute such assignments and/or subleases to assignee(s) and
subtenant(s) identified by Landlord, it being understood that, as between Tenant
and Landlord, Tenant, unless this Agreement is terminated as herein provided,
shall not be responsible for fulfilling any economic obligations in the nature
of inducements in connection with any such assignment or sublease. The parties
agree that the form of assignment attached hereto as Exhibit "A" and the form of
sublease attached hereto as Exhibit "B", with such modifications as may be
necessary to implement a particular transaction, are acceptable.

       (c)    In the event Tenant receives any notices from any assignee or
subtenant, it shall immediately provide copies thereof to Landlord. Tenant shall
not deliver any notices or other communications to any assignee or subtenant
without prior approval of or being requested to do so by Landlord.

<PAGE>   43

       (d)    Any sublease or assignment payments made to Tenant shall be
forthwith remitted to Landlord.

       (e)    In the event Tenant acquires knowledge of any default of
threatened default of any assignee or subtenant, it shall promptly advise
Landlord of the nature and circumstances thereof, to the full extent of Tenant's
knowledge.

6.     Lease Status. Tenant will fully comply with and keep the Tycon Lease in
full force and effect. Tenant will promptly provide Landlord with copies of all
notices and other communications from J.T.L., its agents, successors or assigns,
and shall deliver such notices and take such action with respect thereto as
Landlord may direct. Without limiting the generality of the foregoing, all
notices and statements of any increases in operating costs and expenses and
other notices of any change in terms, conditions or operations shall be timely
delivered promptly. Landlord shall have the right, by notice to Tenant, to cause
Tenant to exercise any of its rights any remedies under the Tycon Lease,
including without limitation the right of audit statements to operating costs
and expenses and the right to exercise options to renew. Provided Tenant
complies with provisions outlined above and Tenant provides Landlord with
adequate notice of monetary obligation Landlord shall incur the expenses of
compliance.

7.     Representations. Tenant represents and warrants to Landlord, as a
material inducement for Landlord entering into this Agreement, that as of the
date of this Agreement:

       (a)    The Tycon Lease is in full force and effect and there exists no
default thereunder by any party which, with the giving of notice or the passage
of time, would entitle any party to terminate the same;

       (b)    Attached hereto as Exhibit "C" is a true and complete copy of the
Tycon Lease, with all amendments and modifications thereof;

       (c)    Except as set forth in Exhibit "C", the Tycon Lease has not been
modified or amended;

       (d)    Attached hereto as Exhibit "D" are true and complete copies of all
notices, communications, statements of operating costs and expenses and
adjustments of rent, audit reports, and all other written materials received
from J.T.L. and its managing agent in Tenant's possession;

       (e)    Attached hereto as Exhibit "E" are true and complete records of
Tenant's share and amounts of operating costs and expenses passed through to
Tenant under the Tycon Lease.

8.     Rent Prior to Indemnity Commencement. In all events Tenant shall be
responsible for payment of all rent and its proportionate share of operating
costs and expenses accrued under the Tycon Lease until the Indemnity
Commencement Date. Such payments shall be made to as specified in the Tycon
Lease and in accordance therewith, and Tenant shall provide Landlord with
reasonably satisfactory documentary evidence of such payment.

9.     Termination; Discharge. Landlord shall be discharged from its indemnity
obligations hereunder, and this Agreement shall terminate, upon (a) any breach
by Tenant of the Lease and the exercise of any remedies thereunder and failure
to cure any such breach within the applicable notice provisions; (b) any breach
by Tenant of its obligations hereunder, or (c) any termination of the Tycon
Lease; provided that Landlord is not responsible for such Termination.

<PAGE>   44
10.    No Third-Party Benefits. The provisions of this Agreement are as between
Landlord and Tenant only and no third party (including without limitation
J.T.L., its managing agent, and its successors and assigns) is intended to be
benefitted hereby.

11.    Independent Covenants. Except to the extent that a breach of the Lease
may operate to terminate this Agreement under subclause (a) of Paragraph 9
above, the covenants and undertakings of the parties set forth herein are
independent of the obligations of the parties under the Lease, and the covenants
and undertakings of the parties set forth in the Lease are independent of the
obligations of the parties under this Agreement.

12.    Notices. All notices permitted or required to be given hereunder shall be
effective upon delivery in the manner and to the parties as provided in the
Lease.

13.    Governing Law. This Agreement is intended to be performed in the
Commonwealth of Virginia and shall be governed by the substantive laws of such
jurisdiction.

14.    Waiver of Jury Trial. In the event of any dispute under this Agreement,
the parties desire that such dispute be tried as to factual matters by a judge,
and not by a jury. Accordingly, each party hereto fully and freely waives trail
by jury in any action, proceeding or counterclaim brought or asserted by either
of the parties hereto against the other.

15.    Assignment. This Agreement is personal between the parties. Tenant shall
not assign any of its rights or obligations under this Agreement without the
written consent of Landlord; any attempted assignment shall be void without such
consent, and shall further constitute a breach of Tenant's obligations
hereunder, terminating Landlord's obligations under this Agreement.

16.    Modifications and Waivers. No modifications, waiver, amendment, or change
of this Agreement, except as otherwise provided herein, shall be valid unless
the same is in writing and signed by the party against which the enforcement of
such modification, waiver, amendment, or change is sought. This Agreement
contains the entire agreement between the parties relating to the subject matter
hereof, and all prior or contemporaneous agreements, understandings,
representations and statements, oral or written, are merged herein.

17.    Exhibits. All exhibits referred to herein and attached hereto are
incorporated by reference into this Agreement.

18.    Construction. Each party hereto and its counsel has reviewed and revised
(or requested revisions of) this Agreement, and the normal rule of construction
that any ambiguities are to be resolved against the drafting party shall not be
applicable in the construction and interpretation of this Agreement.

19.    Captions. The captions of this Agreement are inserted for convenience of
reference only and do not define, describe or limit the scope or the intent of
this Agreement or any term hereof.

<PAGE>   45

20.    Counterparts; Form of Execution. This Agreement may be executed in any
number of counterparts, each of which shall be deemed to be an original, but all
of which together shall constitute one and the same instrument.

IN WITNESS WHEREOF, the parties have caused this Agreement to be executed by
persons duly authorized to bind them to their respective obligations hereunder.

W1TNESS:                              MET LIFE INTERNATIONAL REAL ESTATE EQUITY
                                      SHARES, INC., a Delaware corporation

                                      By: /s/ Michael J. Curran         GG
                                         -----------------------------------
                                              Michael J. Curran,

                                      Title: Assistant Vice President
                                            --------------------------------
                                      Date:  5/29/92
                                            --------------------------------

  /s/ Gail E. Griffith
---------------------------

Name: Gail Griffith
     ----------------------
Date:    5-29-92
     ----------------------

WITNESS:                              KEYVAN RAFIE, a sole proprietorship

                                      By: /s/ Keyvan Rafie
                                         ----------------------------------
                                                   Keyvan Rafie

                                      Title:    A Sole Proprietorship
                                            -------------------------------
                                      Date:       5-18-92
                                            -------------------------------

  /s/ Alexandria P. West
----------------------------

Name: Alexandria P. West
     -----------------------

Date:       5-18-92
     -----------------------

<PAGE>   46

                                LIST OF EXHIBITS

<TABLE>
<S>                     <C>     <C>
Exhibit "A"             -       Form of Assignment

Exhibit "B"             -       Form of Sublease

Exhibit "C"             -       Complete copy of the Lease with all attachments

Exhibit "D"             -       Copies of all: notices; communications; statements of operating costs
                                and adjustments of rent; audit reports; and all other written
                                materials received from J.T.L. and its managing agent.

Exhibit "E"             -       Complete records of Tenant's share and amounts of operating costs
                                and expenses passed through to Tenant under the Tycon Lease.
</TABLE>

<PAGE>   47

                                   EXHIBIT "A"

          of Indemnity Agreement by and between Met Life International
      Real Estate Equity Shares, Inc. and Keyvan Rafei dated, May 29, 1992.

                     (PARTIAL) ASSIGNMENT AND ASSUMPTION OF
                          LESSEE'S INTEREST UNDER LEASE

This (Partial) Assignment and Assumption of Lessee's Interest Under Lease (the
"Assignment") is entered into as of this _____ day of __________, 1992, but
effective for all purposes as of __________,1992 (the "Effective Date"), by and
between Keyvan Rafei ("Assignor") and ______________________,("Assignee").

                                    RECITALS

       R-l.   Assignor is currently party as tenant to that certain Office Lease
(also referred to in said Office Lease as the "Standard Office Lease" and the
"Agreement of Lease", but herein referred to as the "Tycon Lease") dated the
30th day of November, 1987, by and between Assignor and J.T.L. Tycon Towers I
Limited Partnership ("J.T.L."), a Virginia Limited Partnership, as Landlord,
covering premises (the "Tycon Premises") known as Suite 1300 in the building
located at 8000 Towers Crescent Drive, Vienna, Virginia, as amended by Lease
Addendum dated the 30th day of November, 1987. A true copy of the Tycon Lease is
attached hereto as Exhibit A.

       R-2.   Assignor desires to assign to Assignee (the below-described
portion of) its right, title and interest in and to the Tycon Lease and the
Tycon Premises (the "Assigned Interest") upon the terms and conditions hereunder
set forth.

       R-3.   Assignee desires to accept such assignment and to assume the
obligations of Assignor as tenant with respect to the Assigned Interest, and to
be bound in Assignor's stead to the terms of the Tycon Lease with respect to the
Assigned Interest.

       NOW, THEREFORE, in consideration of the mutual promises and covenants
herein contained and other good and valuable consideration, the receipt and
sufficiently of which are hereby acknowledged, the parties agree as follows:

       1.     The above recitations, which are incorporated herein by this
reference, are true and correct.

       2.     Assignor hereby assigns, sets over and transfers unto Assignee
(all of its right, title and interest in and to the Tycon Lease) (a portion of
its right, title and interest in and to the Tycon Premises and the Tycon Lease,
more particularly described as follows:) (IF PARTIAL ASSIGNMENT, DESCRIBE TERM
OR PORTION OF PREMISES AND/OR LEASEHOLD BEING ASSIGNED).

<PAGE>   48

                                   EXHIBIT "B"

            of Indemnity Agreement dated May 29, 1992 by and between
          Met Life International Equity Shares, Inc. and Keyvan Rafei

                               SUBLEASE AGREEMENT

     THIS SUBLEASE AGREEMENT, made and entered into this ___ day of __________,
1992, between ___________________, ("Tenant") and  ________________,
("Subtenant").

                                   WITNESSETH:

     WHEREAS, Tenant is in rightful possession of the premises known as
__________________ located at __________, designated as the ________ floor,
under the __________________ Lease Agreement dated, __________, a copy of which
Lease is attached hereto, marked as Exhibit "A" and made a part of this
Sublease Agreement; and

       WHEREAS, Tenant wishes to sublease Suite __ of the above premises to the
Subtenant on the terms stated herein;

       NOW, THEREFORE, in consideration of the premises and mutual covenants
contained herein, the parties agree as follows:

1.     PREMISES

       The Tenant hereby subleases to the Subtenants, and the Subtenant hereby
hires and leases from the Tenant, approximately _______ square feet of the
premises described in the Lease marked as Exhibit "A" which is herein referred
to as the "Subleased Premises".

 2.    TERM

       The term of the Sublease shall be for a period of___________ months
commencing on _________ and ending on ____________.

 3.    RENT

       Rent for the first year is to be __________________ per month payable on
the first (1st) day of each month. In addition, Subtenant agrees to pay to
Tenant the first (1st) month's rent in full immediately upon execution of this
Sublease Agreement. The rent for the second (2nd) year of the Sublease shall be
increased by ___  percent requiring payment of _______________ per month. There
shall be a four percent (4%) late charge for rent not received on or prior to
the due date for each month's rent.
<PAGE>   49

4.     ALTERATIONS

       The Subtenant may not modify the building design of the Subleased
premises without prior written approval by Tenant, which approval shall not be
unreasonably withheld. Subtenant must additionally coordinate any such building
design modification with ____________________, ("Landlord"). Subtenant shall be
solely responsible for the expense of any approved building design
modifications. Sublessee reserves the right to modify the existing suite entry,
with appropriate Landlord approval. Sublessor shall not be required to return
the suite to its original condition for approved alterations.

5.     PARKING

       During the term of this Sublease and during any extension of this
Sublease, Subtenant shall have the license to use ________ parking spaces in the
building garage at no charge.

                                       SUBLESSOR:

                                       BY:
                                          -------------------------------

                                       TITLE:
                                             ----------------------------

                                       DATE:
                                            -----------------------------

                                       SUBLESSEE:

                                       BY:
                                          -------------------------------

                                       TITLE:
                                             ----------------------------

                                       DATE:
                                            -----------------------------

                               CONSENT OF LANDLORD

       The undersigned is the Landlord under the within described Lease. The
undersigned hereby consents to this Assignment and expressly releases
_______________ from any further liability or obligation as Tenant under the
terms of the Lease.

                                       LANDLORD:

                                       BY:
                                          ------------------------------

                                       TITLE:
                                             ---------------------------

                                       DATE:
                                            -----------------------------
<PAGE>   50
       3.     Assignee hereby accepts the foregoing assignment and the Assigned
Interest and to assume the obligations concomitant therewith, and covenants and
agrees to be bound by all of the terms, covenants and conditions of the Tycon
Lease, and to hold Assignee harmless from any loss or cost whatsoever arising
from or relating to a breach by Assignee of the foregoing covenant, subject only
to the following:

(LIST ANY OBLIGATIONS OF TENANT UNDER TYCON LEASE WHICH WILL NOT BE ASSUMED BY
ASSIGNEE)

       4.     All exhibits attached hereto are by this reference incorporated
herein to the same effect as if fully set forth herein.

       5.     This Assignment contains the entire agreement of the parties
hereto; all other agreements and understandings, whether oral or written, are
hereby merged into this Assignment and are of no force or effect except as so
merged.

       IN WITNESS WHEREOF, Assignor has executed this Assignment in the presence
of the undersigned witness as of the day and year first above-written, and
Assignee has caused this Assignment to be executed by ____________________, its
_____________, and its corporate seal to be hereunder affixed and attested by
________________________________, its (Assistant) Secretary, and Assignee does
hereby appoint the said ________________ and __________________ as its true and
lawful attorney-in-fact to execute and deliver this Assignment as Assignee's act
and deed as of the day and year first above-written.

                                              ASSIGNOR:

WITNESS:                                      KEYVAN RAFEI

        [SIG]                                  /s/ KEYVAN RAFEI
-------------------------                     ---------------------------
NAME                                          Keyvan Rafei

Date: 5/28/92                                 Date: May/28/92
     --------------------                          ----------------------

ATTEST:                                       ASSIGNEE:

                                              ---------------------------

-------------------------
Name

                                              By:
Date:                                            ------------------------
     --------------------
                                              Title:
                                                    ---------------------

(Corporate Seal)                              Date:
                                                   ----------------------
<PAGE>   51

                                   EXHIBIT A

                              AGREEMENT OF SUBLEASE

       THIS AGREEMENT OF SUBLEASE is made and entered into this 24th day of
November 1998 and between Keyvan Rafei (hereinafter referred to as the
"Sublessor") and Global Learning Systems, Inc. a Delaware Corporation (herein
referred to as the "Sublessee").

                                   WITNESSETH:

       WHEREAS, pursuant to that certain office lease, dated May 29, 1992
(hereinafter referred to as the ("Prime Lease")) Sublessor leased certain
premises located at 8330 Boone Boulevard, Vienna, Virginia 22182 (hereinafter
referred to as the "Prime Lease Premises") from Met Life International Real
Estate Equity Shares, Inc. and the current landlord is The Equitable Life
Assurance Society of the United States (hereinafter referred to as the "Prime
Landlord"), and

       WHEREAS, Sublessee desires to sublease from the Sublessor a portion of
the Prime Lease Premises (the "Sublease Premises") and

       WHEREAS, the parties hereto desire to provide for the rental and further
terms and conditions of the Sublease.

       NOW, THEREFORE, for and in consideration of the mutual covenants and
agreements hereinafter set forth, the parties hereto agree as follows:

       1.     Sublease Premises. Sublessee shall initially occupy a portion of
the eighth (8th) floor consisting of approximately 2,493 rentable square feet,
as shown on the attached Exhibit A. In addition, beginning January 1, 1999,
Sublessee shall sublease an additional approximate 1,350 rentable square feet of
adjacent space for a total of approximately 3,843 rentable square feet, subject
to Sublessor's architect's measurement of the Premises.

       2.     Term. The term of the lease shall commence on the Commencement
Date and expire on August 31, 2002.

       3.     Sublease Commencement Date: November 30, 1998 or execution of
sublease, whichever is later.

       4.     Condition of Premises. On the Commencement Date, the Sublessor
shall deliver to the Sublessee the Sublease Premises in "as is" condition,
cleaned by a professional janitorial service, and with all HVAC, plumbing, and
electrical systems in good working order. Notwithstanding the foregoing,
Sublessor shall, at Sublessor's sole cost and expense, construct improvements
required to separate the Sublease Premises and install suite entry doors as
identified in Exhibit B. Such improvements shall be completed pursuant to all
applicable codes and laws by qualified contractors selected by Sublessor. All
improvements shall be completed as quickly as practically possible.

       5.     Use. The Sublessee shall use and occupy the Sublease Premises
solely for general office use.

       6.     Rent. The rent reserved under this Sublease for the term hereby
created shall be payable to the Sublessor at its address: 8330 Boone Boulevard,
Vienna, Virginia 22182, or at such other address as the Sublessor may hereafter
designate in writing, in lawful money of the United States, without notice,
demand, set off or deduction whatsoever, in advance on the first day of each and
every month during the term of this Sublease, provided, however the first
month's rent shall be payable upon execution of this Sublease. In the event that
any rent payment is not received within five (5) days of the date when due, then
Sublessee shall pay a late charge of four percent (4%) of the delinquent amount.
<PAGE>   52

       7.     Base Rental Rate: The Base Rental rate shall be $28.50 per square
foot. The base rent shall be increased by four percent (4%) on each anniversary
of the Sublease Commencement Date. There shall be no operating expense or real
estate tax pass through during the Sublease Term.

       8.     Security Deposit. Upon execution of this Sublease, Sublessee shall
provide a security deposit consisting of an unconditional irrevocable letter of
credit of $50,000 from First Union Bank in a form satisfactory to Sublessor as
attached hereto. Said letter of credit shall be security for the faithful
performance by Sublessee of all the terms, covenants, and conditions of this
Sublease. If Sublessee defaults beyond the expiration of any applicable notice
and grace period with respect to any provision of this Sublease, including, but
not limited to the provisions relating to the payment of rent, Sublessor may
(but shall not be required to) use, apply or retain all or any part of this
security deposit for the payment of rent, or any other sum in default, or for
the payment of any amount which Sublessor may spend or become obligated to spend
by reason of Sublessee's default, or to compensate Sublessor for any other loss
or damage which Sublessor may suffer by reason of Sublessee's default. If any
portion of the deposit is so used or applied, Sublessee must restore the letter
of credit in an amount sufficient to restore the security deposit to its
original amount within five (5) business days after Sublessor's written demand.
Sublessee's failure to do so shall be a material breach of this Sublease. If
Sublessee shall fully and faithfully perform every provision of this Sublease,
the security deposit or any remaining balance shall be promptly released to
Sublessee (or, at Sublessor's option, to the last assignee of Sublessee's
interest) at the expiration of the Sublease term. In the event of termination of
Sublessor's interest in this Sublease, Sublessor shall transfer said deposit to
Sublessor's successor in interest. In such event Sublessee shall look only to
the successor in interest for the return of the security deposit and Sublessor
shall be released from all liability to Sublessee for the return of the
security deposit. Sublessee shall have the right to substitute a different
unconditional irrevocable letter of credit from First Union Bank in the amount
of $50,000 and in form satisfactory to Sublessor.

       9.     Obligations Under the Prime Lease. This Sublease and the parties'
rights under this Sublease shall at all times be subject to and is made upon all
of the terms, covenants, rights and conditions of the Prime Lease, with the same
force and effect as if fully set forth herein at length, and except as otherwise
provided for herein, the Sublessee shall keep, observe and perform or cause to
be kept, observed and performed, faithfully all those terms, covenants, and
conditions of the Sublessor under the Prime Lease with respect to the Sublease
Premises. In addition, Sublessor shall use all reasonable efforts to ensure that
Landlord's obligations under the Prime Lease are satisfied with respect to the
Sublease Premises. A copy of the Prime Lease is attached hereto and made a part
hereof as Exhibit "C." It is understood and agreed that the following provisions
of the Prime Lease are not applicable to this Sublease: Section 5, Base Rental;
Section 33, Personal Liability; Section 34, Security Deposit; Section 35,
Notice; Exhibit C, Work Agreement; Exhibit D, Basic Costs Increase Adjustment;
and Exhibit J, Indemnity Agreement.

       10.    Insurance.

              (a) The Sublessee shall obtain and at all times during the term
hereof maintain, at its sole cost and expense, policies of insurance covering
its fixtures, property and equipment installed and located in the Sublease
Premises, in an amount of not less than one hundred percent (100%) of the
replacement cost of said items against any peril included under insurance
industry practice in Virginia within the classification "fire and extended
coverage," together with insurance against vandalism, malicious mischief and
sprinkler leakage or other sprinkler damage. Any proceeds of such insurance, so
long as this Sublease shall remain in effect, shall be first used to repair or
replace any items that shall have been installed and located in the Sublease
Premises.

<PAGE>   53
                    (b) The Sublessee shall provide and keep in force during the
term of this Sublease with a company or companies approved by the Sublessor a
comprehensive general liability insurance policy in the amount of One Million
and 00/100 Dollars ($1,000,000.00) per person, One Million and 00/100 Dollars
($1,000,000.00) per accident for bodily injury, and One Million and 00/100
Dollars ($1,000,000.00) for property damage, which policy shall contain a
standard legal liability endorsement. The policy shall provide that the
Sublessee and the Sublessor will be given at least thirty (30) days advance
written notice of cancellation or material change in the policy. In addition,
all insurance required of the Sublessee shall be written as a primary policy
coverage, and not contributing with or in excess of any coverage which the
Sublessor or the Prime Landlord may carry.

                    (c) The Sublessee shall deliver to the Sublessor
certificates of such insurance at the beginning of the term of this Sublease,
and thereafter certificates of renewal thereof not less than five (5) days prior
to the expiration of any such policy. In the event that the Sublessee shall fail
to promptly furnish any insurance herein required, the Sublessor may effect the
same and pay the premium for a period not exceeding one (1) year, and the
premium so paid by the Sublessor shall be immediately payable by the Sublessee
as additional rent.

                    (d) All policies of insurance as aforesaid shall name the
Sublessor, the Prime Landlord, and the Prime Landlord's property management
company as additional insureds, as their interest may appear.

           11. Default. The occurrence of any one or more of the following
events shall constitute a default and breach of this Sublease by Sublessee:

                    (a) The failure by Sublessee to make any payment of rent or
any other payment required to be made by Sublessee, as and when due, where such
failure shall continue for a period of five (5) days after written notice by
Sublessor to Sublessee. No notice shall be required for failure to make any
payment if the Sublessee has previously received two (2) notices of non-payment
during the same calendar year

                    (b) The failure by Sublessee to observe or perform any of
the covenants, conditions or provisions of this Sublease to be observed or
performed by the Sublessee, other than described in Sections (a) and (b) above,
where such failure shall continue for a period of ten (10) days after written
notice by Sublessor to Sublessee; provided, however, that if the nature of
Sublessee's default is such that more than ten (10) days are reasonably required
for its cure, then Sublessee shall not be deemed to be in default if Sublessee
commences such cure within said ten (10) day period and thereafter diligently
prosecutes such cure to completion within one hundred twenty (120) days and in
any event prior to the time a failure to cure such default could cause Sublessor
to be subject to prosecution for violation of any law, rule, ordinance or
regulation, or causes, or could cause a default under the Prime Lease;

                  (c) The making by Sublessee of any general assignment or
general arrangement for the benefit of creditors: or the filing by or against
Sublessee of a petition in bankruptcy; or a petition for reorganization or
arrangement under any law relating to bankruptcy (unless, in the case of a
petition filed against Sublessee, the same is dismissed within sixty (60) days);
or the appointment of a trustee or a receiver to take possession of
substantially all of Sublessee's assets located at the Sublease Premises or of
Sublessee's interest in this Sublease, where possession is not restored to
Sublessee within thirty (30) days; or the attachment, execution or other
judicial seizure of substantially all of Sublessee's assets located at the
Sublease Premises or of Sublessee's interest in this Sublease, where such
seizure is not discharged in thirty (30) days;

                  (d)   The failure by Sublessee to fully observe and adhere to
all terms, covenants

                                    3 of 7
<PAGE>   54

and conditions of the Prime Lease.

           12. Subordination. This Sublease is subject and subordinate to the
Prime Lease, to all ground and underlying leases, and to all mortgages and deeds
of trust which may now or hereafter apply to the Prime Lease, the leasehold
estate or estates thereby created or the real property of which the Sublease
Premises form a part, and to any and all renewals, modifications,
consolidations, replacements and extensions thereof.

           13. Assignments and Further Subleases. Sublessee shall not either
voluntarily or by operation of law, assign, transfer, mortgage, pledge,
hypothecate or encumber this Sublease or any interest therein, and shall not
sub-sublet the said Sublease Premises or any part thereof, or any right or
privilege appurtenant, or allow any other person to occupy or use the Sublease
Premises, or any portion, without first obtaining the written consent of
Sublessor and Prime Landlord in each instance, which consent shall not be
unreasonably withheld, delayed or conditioned. Sublessor's consent to one
assignment, sub-subletting, occupation or use by another person shall not be
deemed to be a consent to any subsequent assignment, sub-subletting, occupation
or use by another person. Any such assignment or sub-subletting without such
consent shall, at the option of the Sublessor, constitute a default under this
Sublease. No permitted assignment or sub-subletting shall relieve Sublessee of
any of its obligations or liabilities under this Sublease. Sublessee can merge,
consolidate, or sell all or substantially all of its stock or assets without
obtaining Sublessor's consent conditioned upon the new entity or other successor
in interest expressly assuming all of Sublessee's obligations and liabilities
under this Sublease.

           14. Quiet Enjoyment. The Sublessor covenants and agrees with the
Sublessee that, upon the Sublessee paying the rent reserved in this Sublease and
observing and performing all the terms, covenants and conditions of this
Sublease, the Sublessee may peaceably and quietly enjoy the Sublease Premises
during the term of this Sublease in accordance with the terms, covenants and
conditions of this Sublease.

           15. Indemnification. The Sublessee hereby agrees to indemnify and
hold the Sublessor and the Prime Landlord harmless from and against any cost,
damage, claim, liability or expense (including reasonable attorney's fees)
incurred by or claimed against the Sublessor and/or the Prime Landlord, directly
or indirectly, as a result the Sublessee' negligence, willful misconduct, or any
breach or other violation of this Sublease. The Sublessor hereby agrees to
indemnify and hold harmless from and against any cost, damage, claim, liability
or expense (including reasonable attorney's fees) incurred by or claimed against
Sublessee, directly or indirectly, as a result of Sublessor's gross negligence
or willful misconduct or breach of the Prime Lease by Sublessor.

           16. Notices. Any notice, demand or other communication which must or
may be given or made by either party hereto shall be in writing and shall be
given or made by hand delivery, or by mailing the same by registered or
certified mail, postage prepaid: (i) In the case of Sublesee, to James Martell
Jr.  _____________________________ and (ii) In the case of Sublessor, to Keyvan
Rafei, 8330 Boone Boulevard, Vienna, Virginia 22182, Attention: Mrs. Alexandria
West.

          Either party may, by notice to the other given as aforesaid, designate
a new or additional address to which may such notice, demand or other
communication thereafter shall be given, made or mailed. Any notice, demand or
communication given hereunder by mail shall be deemed delivered when deposited
in a United States Post Office.

          17. Surrender. Upon the expiration or other termination of this
Sublease, the Sublessee shall deliver to the Sublessor the Sublease Premises,
with all of Sublessee's personalty removed, broom clean and in good order,
ordinary wear and tear excepted.

                                    4 of 7
<PAGE>   55

          18. Security and Confidentiality. Sublessee and Sublessor each
acknowledge that the lack of physical boundaries between the Prime Lease
Premises and Sublease Premises prior to the construction of the improvements
specified in paragraph 4 in no way implies that either party shall have right of
access to each other's office space or use of any equipment or trade fixtures
therein.

          19. Parking. Sublessee shall have the right of 3.6 parking spaces per
1,000 square feet leased on an unreserved basis, in the Building garage for no
charge for the entire Sublease Term.

          20. Signaqe. Sublessee will be recognized as a building tenant on the
directory in the main lobby of the building as well as suite entry signage
provided at Sublessor's sole cost and expense. No other signage of the Sublessee
shall be permitted without the express written consent of Sublessor and Prime
Landlord.

          21. Holding Over. In the event of holding over by the Sublessee after
the expiration or other termination of this Sublease, or in the event Sublessee
continues to occupy the Sublease Premises after termination of Sublessee's right
of possession pursuant to paragraph 27 hereof, Sublessee shall, during the
entire holdover period, pay rent equal on a per diem basis, at one hundred fifty
percent (150%) the Base Rental rate which would have been applicable had the
term of this Sublease continued through the period of such holding over by
Sublessee. No holding over by Sublessee after the expiration or other
termination of the term of this Sublease shall be construed to extend the term
of this Sublease. The foregoing provisions of this paragraph are in addition to
and do not affect Sublessor's or Prime Landlord's right of reentry or any other
rights of Sublessor's hereunder or of Prime Landlord under the Prime Lease or as
otherwise provided by law. Sublessee shall indemnify and hold Sublessor harmless
from all loss or liability, including without limitation, all attorney's fees
and costs, arising from or related to any unauthorized holding over.

          22. Condition Precedent. The effectiveness of this Sublease is
expressly subject to and conditional upon obtaining Prime Landlord's written
consent to this Sublease, pursuant to Section 17 of the Prime Lease.

          23. General Provisions.

                  (a) Broker Commission: The parties represent and warrant that
                      they have dealt with no broker, agent or other person in
                      connection with this transaction other than TransWestern
                      Carey Winston, LLC, representing the Sublessor and Julien
                      J. Studley, Inc. representing Sublessee. Each party
                      agrees to indemnify and hold the other harmless from and
                      against any claims by any other broker, agent or any
                      other person claiming a commission or other form of
                      compensation by virtue of having dealt with Sublessor or
                      Sublessee with regard to this leasing transaction.

                  (b) Conference Rooms: Upon reasonable prior notice from
                      Sublessee and subject to availability, Sublessor shall
                      grant Sublessee use of the conference rooms adjacent to
                      the main reception area.

                  (c) Kitchen & Reception area Privileges: Sublessee shall have
                      the right to utilize one (1) of Sublessors existing
                      kitchens on a shared basis and receive visitors in the
                      Sublessor's reception area.

                  (d) Benefit and Burden. The covenants, conditions, agreements,
                      terms and provisions herein contained shall be binding
                      upon, and shall inure to the benefit of, the parties
                      hereto and each of their respective personal
                      representatives, successors, heirs, executors,
                      administrators and assigns.

                                    5 of 7

<PAGE>   56

                    (e) Governing Law. It is the intention of the parties hereto
                        that this Sublease shall be construed and enforced in
                        accordance with the laws of the Commonwealth of
                        Virginia.

                    (f) Entire Agreement. This Sublease contains the final and
                        entire agreement between the parties hereto, and they
                        shall not be bound by any terms, statements, conditions
                        or representations, oral or written, express or implied,
                        not herein contained.

                    (g) Conflicts Between This Sublease and the Prime Lease.
                        With respect to the relationship between the Sublessor
                        and the Sublessee, the terms and conditions of this
                        Sublease shall take precedence with respect to any
                        conflict between the terms and conditions contained
                        herein and the terms and conditions of the Prime Lease.
                        Nothing herein shall be construed in any way to affect
                        the rights and obligations of the Sublessor and the
                        Prime Landlord under the Prime Lease.

                    (h) Captions. The captions throughout this Sublease are for
                        convenience or reference only and the words contained
                        therein shall in no way be held or deemed to define,
                        limit, describe, explain, modify, amplify or add to the
                        interpretation, construction or meaning of any provision
                        of or the scope or intent of this Sublease, nor in any
                        way effect this Sublease.

                    (i) Singular and Plural. Wherever appropriate herein, the
                        singular includes the plural and the plural includes the
                        singular.

                    (j) Counterpart. This Sublease may be executed in several
                        counterparts, but all counterparts shall constitute but
                        one and the same instrument.

                    (k) Time. Time is of the essence with respect to all of
                        Sublessee's obligations.

          24. Attorney's Fees. In the event of any litigation between the
parties arising from or related to this Sublease, the prevailing party shall be
entitled to recovery of all reasonable attorneys fees, costs and expenses as
fixed by the court.

          25. Waiver of Jury Trial. The parties hereby waive all right to trial
by jury in any claim, action, proceeding or counterclaim between the parties on
any matters arising out of, or related to, this Sublease, the relationship of
Sublessor and Sublessee and/or Sublessee's use or occupancy of the Sublease
Premises.

          26. Remedies. In the event of any default or breach as defined in
section 11 hereof by Sublessee, Sublessor may at any time thereafter, with or
without notice or demand and without limiting Sublessor in the exercise of any
other right or remedy which Sublessor may have by reason of such default or
breach:

                  (a) Terminate Sublessee's right to possession of the Sublease
Premises by any lawful means, in which case this Sublease shall terminate
and Sublessee shall immediately surrender possession of the Sublease Premises to
Sublessor. In such event Sublessor shall be entitled to recover from Sublessee
all damages incurred by Sublessor by reason of Sublessee's default including,
but not limited to, reasonable attorneys' fees; the cost of recovering
possession of the Sublease Premises: expenses of relettng including repair and
alteration of the Sublease Premises; any brokerage fees; any defaulted rent or
additional rent payments; the difference, if any, between the unpaid rent for
the balance of the Sublease term and the amount received by Sublessor for any
reletting of the Sublease Premises during the balance of the Sublease term;
and that portion of the leasing commission paid by Sublessor and applicable to
the unexpired

                                    6 of 7
<PAGE>   57
term of this Sublease. Unpaid installments of rent or other sums shall bear
interest from the date due at the rate of eighteen percent (18%) per annum or
the highest rate permitted by applicable law;

              (b) Maintain Sublessee's right to possession, in which case this
Sublease shall continue in effect whether or not Sublessee shall have abandoned
the Sublease Premises. In such event Sublessee shall continue to be liable for
all rent, and all other charges due under this Sublease, in addition to all
costs (including reasonable attorney's fees) and other damages arising from
Sublessee's default; or

              (c) Pursue any other remedy now or hereafter available to
Sublessor under the laws or judicial decisions of the Commonwealth of Virginia.
Sublessee waives all rights of redemption granted by law. This means that once
Sublessee has committed a default and failed to cure that default within any
cure period provided by this Sublease, Sublessee waives all rights under law to
later cure the default and reclaim its interest in this Sublease or the
Sublease Premises.

          27. Waivers. No waiver or oversight of any breach of any covenant,
condition or agreement contained herein, or compromise or settlement relating
to such a breach, shall operate as a waiver of the covenant, condition or
agreement itself, or of any subsequent breach thereof.

          28. No Alterations. Sublessee shall not make, authorize or allow any
structural alterations, modifications, repairs or additions to the Sublease
Premises, or any portion thereof, without the prior written consent of
Sublessor and Prime Landlord.

          29. Notice of Defects. Sublessee will give Sublessor prompt notice
of any known defect, breakage, malfunction or damage to or in the structure,
equipment or fixtures in or on the Sublease Premises. This covenant, however,
does not obligate, and is not to be understood, interpreted, construed, or an
any way to imply that Sublessor as obligated or expected to repair or correct
such defect, breakage, malfunction or damage.

          30. Access to Premises. Sublessor shall provide Sublessee with a
reasonable number of security cards and keys to the premises and buildings at
no cost to the Sublessee.

         IN WITNESS HEREOF, the Sublessor and the Sublessee have executed this
         Sublease on the day and year first herein above written.

         SUBLESSOR: KEYVAN RAFEI                SUBLESSEE:

         By:     [SIG]          (SEAL)          BY:    [SIG]             (SEAL)
            --------------------                   ----------------------

         Date: 11/24/98                         Its:  Chairman
              ------------------                    ---------------------

                                                Date:   11/24/98
                                                     --------------------

                                     7 of 7

<PAGE>   58

                                   [FLOOR PLAN]

<PAGE>   59

                                   [FLOOR PLAN]

<PAGE>   60

                              CONSENT TO SUBLEASE

          THIS CONSENT TO SUBLEASE is entered into between The Equitable Life
Assurance Society of the United States ("Landlord"), and Keyvan Rafie
("Tenant"), and executed on this ______ day of December, 1998.

          WHEREAS, Met Life International Real Estate Equity Shares, Inc., as
landlord, and Tenant entered into a Lease Agreement dated May 29, 1992 (the
"Lease"), for premises containing approximately 21,041 square feet of Net
Rentable Area (the "Premises") on the eighth (8th) floor of the building
located at 8330 Boone Boulevard, Vienna, Virginia; and

          WHEREAS, the Lease is scheduled to expire on August 31, 2002 (the
"Lease Termination Date"); and

          WHEREAS, Tenant, as sublessor, wishes to enter into an Agreement of
Sublease (the "Sublease") with Global Learning Systems, Inc. ("Sublessee"), for
a total of approximately 3,843 rentable square feet (2,493 rentable square feet
of such space to be available upon execution of this Consent to Sublease, and
the remainder of such space to become available as of January 1, 1999)
contained within the Premises (the "Subleased Premises") (a copy of such
Sublease is attached hereto as EXHIBIT A); and

          WHEREAS, Tenant has sought Landlord's consent to sublease the
          Subleased Premises; and

          WHEREAS, Landlord is willing to consent to the Sublease between
Tenant and Sublesee, but only on the conditions and terms contained herein.

          NOW THEREFORE, in consideration of the foregoing and other good and
valuable consideration, the receipt and sufficiency of which is acknowledged by
all parties, Landlord hereby consents to Tenant's subletting the Subleased
Premises to Sublessee and to Sublessee's use of the Subleased Premises upon the
following conditions:

          1.  The Sublease shall be subordinate to the Lease, and Subtenant
shall perform all obligations of Tenant under said Lease, with respect to the
Sublease Premises.

          2.  The Sublease shall terminate, unless sooner provided in the
Sublease, on the Lease Termination Date.

          3.  Sublessee shall comply strictly with the use and operation
provisions contained in Section 4 of the Lease. Any term of the Sublease that
in any way conflicts with or alters the provisions of the Lease shall be of no
effect as to Landlord and Landlord shall not assume any obligations as landlord
under the Sublease and Sublessee shall not acquire any rights under the
Sublease directly assertable against Landlord under the underlying Lease.
<PAGE>   61
          4.  There shall be no further subleases of the Premises or the
Subleased Premises, without first obtaining the prior written consent of
Landlord as otherwise provided in the Lease.

          5.  Landlord's consent to the Sublease shall not (a) make Landlord a
party to the Sublease, (b) create any privity of contract between Landlord and
Sublessee or create any other contractual liability or duty on the part of the
Landlord to the Sublessee, (c) constitute its consent or waiver of consent to
any subsequent sublease or sub-sublease, (d) in any manner increase, decrease
or otherwise affect the rights and obligations of Landlord and Tenant under the
Lease, in respect of the Subleased Premises, or (e) constitute a waiver or a
release of Tenant of any covenant or obligation contained in the Lease, in the
event Landlord accepts or collects rent from Sublessee.

          6.  In the event of a default under the Lease, Tenant hereby assigns
to Landlord the rent due to Tenant from Sublessee and hereby authorizes
Sublessee to pay said rent directly to Landlord, at Landlord's option.

          WITNESS, the signatures of the parties hereto:

                                    LANDLORD:

                                    THE EQUITABLE LIFE ASSURANCE
                                    SOCIETY OF THE UNITED STATES

                                    By:        /s/ BRENDA E. MCKINNEY
                                           ------------------------------------
                                    Name:          BRENDA E. MCKINNEY
                                           ------------------------------------
                                    Title:         INVESTMENT OFFICER
                                           ------------------------------------
                                    TENANT:
                                             /s/ KEYVAN RAFIE
                                    ------------------------------------
                                    Name: Keyvan Rafie

                                      -2-

<PAGE>   62

          9.  Default. If the Sublessee shall default with respect to this
Sublease and the Sublease Premises beyond any applicable cure period, the
Sublessor shall have all of the rights and remedies accorded to the Prime
Landlord under the Prime Lease. In the event of default by Sublessee, Sublessor
shall provide written notice to Sublessee identifying the default. Sublessor
agrees to grant to Sublessee a seven (7) day cure period from the notice date.

          10. Subordination. This Sublease is subject and subordinate to the
Prime lease, to all ground and underlying leases, and to all mortgages and
deeds of trust which may now or hereafter affect such leases, the leasehold
estate or estates thereby created or the real property of which the Sublease
Premises form a part. and to any and all renewals, modifications,
consolidations, replacements and extensions thereof, provided that the
Sublessor agrees not to effect any modification or amendment of the Prime lease
which might adversely affect the rights of the Sublessee hereunder without the
written consent of the Sublessee in each case.

          11. Assignments and Further Subleases. Sublessee may not assign or
further sublease the Sublease Premises without the prior approval of Sublessor
and Prime Landlord, which consent shall not be unreasonably withheld, delayed,
or conditioned.

          12. Quiet Enjoyment. The Sublessor covenants and agrees with the
Sublessee that, upon the Sublessee paying the rent reserved in this Sublease
and observing and performing all the terms, covenants and conditions of this
Sublease, the Sublessee may peaceably and quietly enjoy the Sublease Premises
during the term of this Sublease, in accordance with the terms, covenants and
conditions of this Sublease.

          13. Indemnification. The Sublessee hereby agrees to indemnify and hold
the Sublessor and the Prime Landlord harmless from and against any cost, damage,
claim, liability or expense (including reasonable attorney's fees) incurred by
or claimed against the Sublessor and/or the prime Landlord, directly or
indirectly, as a result of Sublessee negligence or willful misconduct. The
Sublessor hereby agrees to indemnify and hold harmless from and against any
cost, damage, claim, liability or expense (including reasonable attorney's fees)
incurred by or claimed against Sublessee, directly or indirectly, as a result of
Sublessor's gross negligence or willful misconduct.

          14. Notices. Any notice, demand or other communication which must or
may be given or made by either party hereto shall be in writing and shall be
given or made by hand delivery, or by mailing the same by registered or
certified mail, postage prepaid: (i) In the case of Sublessee, Tenant
HealthSystems, Inc., 14001 Dallas Parkway, Dallas, Texas 75240, Attention: John
Mastenich (and Don Smith at the Premises), with a copy to the Sublease Premises;
and (ii) In the case of Sublessor, to Keyvan Rafei, 8330 Boone Boulevard,
Vienna, Virginia 22182, Attention: Mrs. Alexander West.

          Either party may, by notice to the other given as aforesaid designate
a new or additional address to which any such notice, demand or other
communication thereafter shall be given, made or mailed. Any notice,  demand or
communication given hereunder by mail shall be deemed delivered when deposited
in a United States Post Office.

          15. Surrender. Upon the Expiration Date of this Sublease, the
Sublessee shall deliver to the Sublessor the Sublease Premises, with all of
Sublessee's personaltry removed, broom cleaned and in good order, ordinary
wear and tear excepted.

<PAGE>   63
          16. Broker. Sublessor and Sublessee warrant and represent to each
other that other than CB Commercial Group, Inc. (Sublessee's representative) and
Barnes, Morris, Pardoe & Foster, Inc. (Sublessor's representative)
(collectively, "the Representatives"), no broker brought about this transaction
or dealt with either party in connection herewith: Sublessor shall pay the
Representatives a commission pursuant to a separate agreement between Sublessor
and the Representatives.

          17. Security and Confidentiality. Sublessee and Sublessor each
acknowledge through this Sublease that the lack of physical boundaries between
the Prime lease Premises and Sublease Premises prior to construction of the
improvements specified in Paragraph 3 in no way implies that either party shall
have right of access to each other's office space or use of any equipment or
trade fixtures therein.

          18. Early Access for Telecommunications and Networking. Upon full
execution of this Sublease and ratification thereof by Landlord, Sublessee
shall be entitled to enter the Sublease Premises for the purposes of installing
its telecommunications and network systems and for any other reasonable
activities related to Sublessee's occupancy and use of the Sublease Premises.
Sublessee shall coordinate all pre-occupancy activities with Sublessor and
Landlord.

          19. Parking. Sublessee shall have the right to eighteen (18) free
unreserved parking spaces during the term of the Sublease. In the event that
during the term of the Sublease the Prime Landlord assigns or allocates the
areas for applicable paring by the Sublessor, then the Sublessor and Sublessee
shall share such parking proportionately, including any and all exclusive
parking in the covered areas of the parking structure.

          20. Signage. Subtenant will be recognized as a building tenant on the
directory in the main lobby of the building as well as suite entry signage
provided at Sublandlord's sole cost and expense.

          21. Holding Over. It is expressively understood that the Sublessor's
Prime Lease with the Prime Landlord terminates on September 30, 2002. If
Subtenant remains in possession of the Sublease Premises or any part thereof
after September 30, 2002, without the express written consent or the
Sublandlord and Prime Landlord, Subtenant shall become a Subtenant at
sufferance only, at a rental rate of two hundred percent (200%) of the rent in
effect upon such expiration including all additional rent in effect during the
last month of the term of this Sublease. The foregoing provisions of this
paragraph are in addition to and do not affect Sublessor's or Prime Landlord's
right of reentry or any other rights of Sublessor's hereunder or of Prime
Landlord under the Prime Lease or as otherwise provided by law. If Subtenant
shall fail to surrender the Demised Premises on September 30, 2002, despite
demand to do so by Sublessor and/or Prime Landlord, Subtenant shall indemnify
and hold Sublessor harmless from all loss or liablility, including without
limitation, any claim made by Prime Landlord or by any succeeding Lessee
founded on or reulting from such failure to surrender and any attorney's fees
and costs.

          22. Condition Precedent. The effectiveness of this Sublease is
expressly subject to and conditional upon obtaining Lessor's written consent to
this Sublease, subject to Section 17 of the Prime Lease.

<PAGE>   64

          23. General Provisions.

              (a)   Benefit and Burden. The covenants, conditions, agreements,
terms and provisions herein contained shall be binding upon, and shall inure to
the benefit of, the parties hereto and each of their respective personal
representatives, successors, heirs, executors, administrators and assigns.

              (b)   Governing Law. It is the intention of the parties hereto
that this Sublease shall be construed and enforced in accordance with the laws
of the Commonwealth of Virginia.

              (c)   Entire Agreement. This Sublease contains the final and
entire agreement between the parties hereto, and they shall not be bound by any
terms, statements, conditions or representations, oral or written, express or
implied, not herein contained.

              (d)   Conflicts Between This Sublease and the Prime Lease. With
respect to the relationship between the Sublessor and the Sublessee, the terms
and conditions of this Sublease shall take precedence with respect to any
conflict betwen the terms and conditions contained herein and the terms and
conditions of the Prime lease. Nothing herein shall be construed in any way to
affect the rights and obligations of the Sublessor and the Prime Landlord under
the Prime Lease.

              (e)   Captions. The captions throughout this Sublease are for
convenience or reference only and the words contained therein shall in no way
be held or deemed to define, limit, describe, explain, modify, amplify or add
to the interpretation, construction or meaning of any provision of or the scope
or intent of this Sublease, nor in any way effect this Sublease.

              (f)   Singular and Plural. Wherever appropriate herein, the
singular includes the plural and the plural includes the singular.

              (g)   Counterpart. This Sublease may be executed in several
counterparts, but all counterparts shall constitute but one and the same
instrument.

          IN WITNESS WHEREOF, the Sublessor and the Sublessee have executed
this Sublease on the day and year first herein above written.

SUBLESSOR: KEYVAN RAFEI                   SUBLESSE: TENET HEALTHSYSTEMS, INC.

By:            [SIG]             (SEAL)   BY:           [SIG]           (SEAL)
   ------------------------------            ---------------------------

Its:            [SIG]            (SEAL)   Its:      VICE PRESIDENT      (SEAL)
    -----------------------------             --------------------------

Date:         [SIG]              (SEAL)   Date:        23 OCT 97        (SEAL)
     ----------------------------              -------------------------

<PAGE>   65

                             AGREEMENT OF SUBLEASE

       THIS AGREEMENT OF SUBLEASE is made and entered into on this ____ day of
October 1997 by and between Keyvan Rafei (hereinafter referred to as the
"Sublessor"), and Tenet HealthSystems, Inc., a Delaware Corporation (hereinafter
referred to as the "Sublessee").

                                  WITNESSETH:

       WHEREAS, pursuant to that certain office lease, dated May 29, 1992
(hereinafter referred to as the "Prime Lease") whereby Subleassor leased certain
premises located at 8330 Boone Boulevard, Vienna, Virginia 22182 (hereinafter
referred to as the "Prime Lease Premises") from American Center (hereinafter
referred to as the "Prime Landlord").

       WHEREAS, Sublessee desires to sublease from the Sublessor a portion of
the prime Lease Premises (the "Sublease Premises"); and

       WHEREAS, the parties hereto desire to provide for the rental and further
terms and conditions of the Sublease.

       NOW, THEREFORE, for and in consideration of the mutual covenants and
agreements hereinafter set forth, the parties hereto agree as follows:

       1.  Sublease Premises. The Sublessor does hereby sublease to the
Sublessee, and the Sublessee does hereby lease from the Sublessor, for the term
and upon the conditions hereinafter provided, approximately 5,454 square feet of
the Prime Lease Premises, as outlined on the plan attached hereto and made a
part hereof as Exhibit "A."

       2.  Term. The term of this Sublease shall commence on occupancy of the
Sublease Premises but in no event later than November 1, 1997 (the "Commencement
Date") and expiring on September 30, 2002.

       3.  Condition of Premises. On the Commencement Date, the Sublessor shall
deliver to the Sublessee the Sublease Premises in "as is" condition, cleaned by
a professional janitorial service, and with all HVAC, plumbing, and electrical
systems in good working order. Notwithstanding the foregoing, Sublessor shall,
at Sublessor's sole cost and expense, construct all improvements required to
separate the Sublease Premises from the Prime Lease Premises and create a new
reception area for Subtenant.  Such improvements shall be completed pursuant to
all applicable codes and regulations in first class manner and by qualified
contractors. All improvements shall be completed as quickly as practically
possible.

       4.  Use. The Sublessee shall use and occupy the Sublease Premises solely
for general office use.

       5.  Rent. The rent reserved under the Sublease for the term hereby
created shall be payable to the Sublessor at its address: 8330 Boone Boulevard,
Vienna, Virginia, 22182, or at such other address as the Sublessor may hereafter
designate in writing, in lawful money of the United States, without notice,
demand, set off or deduction whatsoever, in advance on the first

<PAGE>   66

day of each and every month during the term of the Sublease, provided, however
the first month's rent shall be payable upon execution of this Sublease. The
rent due and payable by Sublessee to Sublessor shall be as follows:

<TABLE>
<CAPTION>

------------------------------------------------------------------------------------------------
       YEAR        PERIOD                 RENT/SQUARE          RENT/PERIOD          MONTHLY
                                              FOOT                                 INSTALLMENT
------------------------------------------------------------------------------------------------
<C>           <S>                         <C>                  <C>                 <C>
        1     Lease Commencement             $28.00              $152,712.00       $12,726.00
              Date-October 31, 1998
------------------------------------------------------------------------------------------------
        2     November 1, 1998-              $28.84              $1527,293.36      $13,107.78
              October 31, 1999
------------------------------------------------------------------------------------------------
        3     November 1, 1999-              $29.71              $162,038.34       $13,503.20
              October 31, 2000
------------------------------------------------------------------------------------------------
        4     November 1, 2000-              $30.60              $166,892.40       $13,907.70
              October 31, 2001
------------------------------------------------------------------------------------------------
        5     November 1, 2001-              $31.51              $157,534.25       $14,321.30
              September 30, 2002
------------------------------------------------------------------------------------------------

</TABLE>
            6.  Additional Rent.

                (a)  The Prime Lease obligates Sublessor to make payments to
Prime Landlord on the basis of increases in operating expenses and real estate
taxes. Subtenant agrees to pay Sublessor additional rent equal to Subtenant's
allocable share of such increases above the amount payable by Sublessor to Prime
Landlord during the Base Year. For purposes of the Paragraph 6, the Base Year
shall be calendar year 1998 and Subtenant's allocable share shall be the product
of (i) the amount of such increase above the Base Year payable from time to time
by Sublessor under the Prime Lease, multiplied by (ii) a fraction, the numerator
of which shall be the number of square feet of rentable area in the Subleased
Premises, and the denominator of which shall be the number of square feet of
rentable area leased from time to time by Sublessor pursuant to the Prime Lease.
Payments of additional rent by Subtenant shall commence on January 1, 1999 and
shall be made to Sublessor on the same basis, in the same manner, and at the
same time or times as Sublessor is required to pay Prime Landlord additional
rent under the Prime Lease. Sublessor agrees to furnish Subtenant a copy of any
statement received by Sublessor from Prime Landlord showing amounts of
additional rent to be paid by Sublessor, under the Prime Lease and a statement
setting forth Subtenant's allocable share of such amounts. Sublessor agrees to
reimburse Subtenant for Subtenant's allocable share of any reimbursements to
Sublessor that result from any over payments made during the preceding calendar
year within thirty (30) days after Sublessor receives such reimbursement from
Prime Landlord. It is understood and agreed that Subtenant's liability for
additional rent and Sublessor's responsibility to refund any overpayments shall
survive the expiration or termination of this Sublease.

                (b)  If Subtenant's responsibility for paying its proportionate
share of increases in operating expenses and real estate taxes will commence or
expire on a day other than the first day or the last day of a calendar year, the
increases in operating expenses and real estate taxes to
<PAGE>   67
be paid by Subtenant for such calendar years shall be apportioned by multiplying
the amount of Subtenant's proportionate share thereof for the full calendar year
by a fraction, the numerator of which is the number of days during such calendar
year falling within the Sublease, and the denominator of which is 365.

       7.  Obligations Under the Prime Lease. This Sublease and the Sublessee's
rights under this Sublease shall at all time be subject to and is made upon all
of the terms, covenants, rights and conditions of the Prime Lease, with the same
force and effect as if fully set forth herein at length, and except as otherwise
provided for herein, the Sublessee shall keep, observe and perform or cause to
be kept, observed and performed, faithfully all those terms, covenants, and
conditions of the Sublessor under the Prime Lease with respect to the Sublease
Premises. In addition, Sublessor shall use all reasonable efforts to ensure that
landlord's obligations under the Prime Lease are satisfied with respect to the
sublease Premises. A copy of the Prime Lease is attached hereto and made a part
hereof as Exhibit "B."

       8.  Insurance.

           (a) The Sublessee shall obtain and at all times during the term
hereof maintain, at its sole cost and expense, policies of insurance covering
its fixtures, property and equipment installed and located in the Sublease
Premises, in an amount of not less than one hundred percent (100%) of the
replacement cost of said items against any peril included under insurance
industry practice in Virginia within the classification "fire and extended
coverage." together with insurance against vandalism, malicious mischief and
sprinkler leakage or other sprinkler damage. Any proceeds of such insurance, so
long as this Sublease shall remain in effect, shall be first used to repair or
replace any items that shall have been installed and located in the Sublease
Premises.

           (b) The Sublessee shall provide and keep in force during the term of
this Sublease with a company or companies approved by the Sublessor a
comprehensive general liability insurance policy in the amount of One Million
and 00/100 Dollars ($1,000,000.00) per person. One Million and 00/100 Dollars
($1,000,000.00) per accident for bodily injury, and One Million and 00/100
Dollars ($1,000,000.00) for property damage, which policy shall contain a
standard fire legal liability endorsement. The policy shall provide that the
Sublessee and the Sublessor will be given at least thirty (30)days advance
written notice of cancellation or material change in the policy. In addition,
all insurance required of the Sublessee shall be written as a primary policy
coverage, and not contributing with or in excess of any coverage which the
Sublessee or the Prime Landlord may carry.

           (c)  The Sublessee shall deliver to the Sublessor certificates of
such insurance at the beginning of the term of this Sublease, and thereafter
certificates of renewal thereof not less than five (5) days prior to the
expiration of any such policy. In the event that the Sublessee shall fail
promptly to furnish any insurance herein required, the Sublessor may effect the
same and pay the premium for a period not exceeding one (1) year, and the
premium so paid by the Sublessor shall be immediately payable by the Sublessee
as additional rent.

           (d)  All policies of insurance as aforesaid shall name the Sublessor,
the Prime Landlord, and the Prime Landlord's property management company as
additional insureds, as their interest may appear.
<PAGE>   68

                               LANDLORD'S CONSENT

       Subject to the terms of this Landlord's Consent, MET LIFE INTERNATIONAL
REAL ESTATE EQUITY SHARES, INC. ("LANDLORD"), a Delaware corporation, hereby
consents to the Sublease (the "Sublease") dated October 27, 1997, by and between
KEYVAN RAFEI ("Sublandlord"), a sole proprietorship, and TENET HEALTHSYSTEMS,
INC. ("Subtenant"), a Delaware corporation. Sublandlord and Subtenant represent
and warrant and agree as follows:

       1.     A correct and complete copy of the Sublease is attached hereto.

       2.     Landlord's consent to the Sublease shall not make Landlord a party
to the Sublease.

       3.     Notwithstanding any provisions to the contrary in the Sublease,
the Sublease shall not create any contractual privity or duty on the part of
Landlord to Subtenant.

       4.     The Sublease shall not in any manner increase, decrease, or
otherwise affect the rights and obligations of Landlord and Sublanlord, as the
Tenant under the Lease Agreement (the "Lease") dated May 29, 1992.

       5.     Subtenant has received a correct and complete copy of the Lease
and understands the terms thereof.

       6.     Any parking spaces used by Subtenant shall decrease the number of
parking spaces available for Sublandlord under the terms of the Lease.

       7.     Notwithstanding anything to the contrary in the Sublease, the term
of the Sublease shall end on August 30, 2002, one day before August 31, 2002,
the expiration of the Lease Term.

       8.     Subtenant shall use and occupy the Sublease Premises solely for
general office purposes and for no other use or purpose without the prior
written consent of Landlord and Sublandlord. Sublandlord and Subtenant confirm
that they will not operate the Premises as a place of public accommodation for
the purposes of the Americans with Disability Act ( the "ADA"), as it may be
amended from time to time. Sublandlord and Subtenant shall not use or occupy the
Premises (including the Sublease Premises) for any unlawful purpose or in any
manner that will constitute waste, nuisance or unreasonable annoyance to
Landlord or other tenants of the Complex or for any purpose prohibited in the
rules and regulations promulgated by Landlord. Sublandlord and Subtenant
acknowledge that a use which attracts a large number of people (such as an
ambulatory care facility, employment agency or public defender's office) would
cause unreasonable annoyance to Landlord and the other tenants of the Complex.
If any present or future law, ordinance, regulation or order requires an
occupancy permit for the Premises (including the Sublease Premises), Sublandlord
and/or Subtenant will obtain such permit at their own expense.

       9.     If Sublandlord exercises its right to terminate the Lease, the
Sublease shall be terminated at the same time the Lease is terminated.

       10.    The option to lease the Expansion Space in Exhibit "H" and the
renewal option in
<PAGE>   69

Exhibit "I" are personal to Sublandlord and are not exercisable by Subtenant.

       11.    Landlord hereby approves the improvements to the Sublease Premises
as described in Exhibit A attached hereto. All such improvements shall be
constructed at no expense to Landlord in accordance with the terms of the Lease.

       12.    This Landlord's Consent shall not be construed as a consent or
waiver of any of Landlord's rights under the Lease with respect to any future
sublet or assignment.

       In consideration for Landlord's consent to the Sublease, Sublandlord
hereby represents and warrants to Landlord as follows:

                     (a)    The improvements and space required to be furnished
              to Sublandlord under the terms of the Lease and all other matters
              required to be furnished or performed by Landlord have been
              completed in all respects in accordance with the terms of the
              Lease.

                     (b)    All duties of Landlord of an inducement nature have
              been fulfilled and all other obligations required to be performed
              or observed by Landlord have been duly and fully performed or
              observed by Landlord.

                     (c)    Landlord has not waived the performance or
              observance by Sublandlord of any of the terms, covenants, or
              conditions to be performed or observed by Sublandlord under the
              Lease. Landlord has made no representations or commitments, oral
              or written, or undertaken any obligations other than as may be
              expressly set forth in the Lease.

                     (d)    The Lease continues in full force and effect in
              accordance with its terms and is enforceable against Landlord and
              Sublandlord in accordance with its terms. No claim, set-off or
              defense exists for the benefit of Sublandlord against Landlord in
              connection with the Lease, and to the extent any claims, set-offs
              or defenses exist, they are hereby waived and relinquished in
              their entirety.

                                  PAGE 2 OF 3
<PAGE>   70

       IN WITNESS WHEREOF, Landlord, Sublandlord, and Subtenant have executed
this Landlord's Consent under seal as of November __, 1997.

                                            SUBLANDLORD:

WITNESS:

[SIG]                                       /s/ KEYVAN RAFEI              [SEAL]
----------------------------                ------------------------------
                                            Keyvan Rafei

                                            SUBTENANT:

WITNESS:                                    TENET HEALTHSYSTEMS, INC.
                                             a Delaware corporation

[SIG]                                       By: /s/ DONALD W. THAYER      [SEAL]
----------------------------                    --------------------------
                                                Name:  DONALD W. THAYER
                                                Title: VICE PRESIDENT

                                            LANDLORD:

WITNESS:                                    MET LIFE INTERNATIONAL REAL ESTATE
                                            EQUITY SHARES, INC.
                                             a Delaware corporation

[SIG]                                       By: [SIG]                     [SEAL]
----------------------------                    --------------------------
                                                Name:  [SIG] T. ANDREW BEHYMER
                                                Title: VICE PRESIDENT

                                  PAGE 3 OF 3
<PAGE>   71

                                    EXHIBIT A

[Description of demising wall and new reception area to be built at
Sublandlord's expense]

<PAGE>   72

                              CONSENT TO SUBLEASE

              THIS CONSENT TO SUBLEASE is entered into between The Equitable
Life Assurance Society of the United States ("Landlord"), Keyvan Rafei
("Tenant"), Tenet HealthSystems Medical, Inc. ("Sublessor") and ChoicePoint
Services Inc. ("Sublessee"), and executed on this 29th day of May, 1998.

              WHEREAS, Met Life International Real Estate Equity Shares, Inc.,
as landlord, and Tenant entered into a Lease Agreement dated May 29, 1992 (the
"Lease"), for premises containing approximately 21,041 square feet of Net
Rentable Area (the "Premises") on the eighth (8th) floor of the building located
at 8330 Boone Boulevard, Vienna, Virginia; and

              WHEREAS, the Lease is scheduled to expire on August 31, 2002 (the
"Lease Termination Date"); and

              WHEREAS, Tenant, as sublessor, and Sublessor entered into a Master
Sublease dated October 27, 1997, under which Tenant sublet approximately 5,454
square feet of Net Rentable Area (the "Subleased Premises") of the Premises of
Sublessor; and

              WHEREAS, Sublessor wishes to further sublease the Subleased
Premises to Sublessee and has entered into a Sublease agreement (the "Sublease")
with Sublessee, for the Subleased Premises; and

              WHEREAS, Tenant, Sublessor and Sublessee have sought Landlord's
consent to further sublease the Subleased Premises; and

              WHEREAS, Landlord is willing to consent to the Sublease between
Sublessor and Sublessee, but only on the conditions and terms contained herein.

              NOW THEREFORE, in consideration of the foregoing and other good
and valuable consideration, the receipt and sufficiency of which is acknowledged
by all parties, Landlord hereby consents to Sublessor's subletting the Subleased
Premises to Sublessee and to Sublessee's use of the Subleased Premises upon the
following conditions;

              1.     The Sublease shall be subordinate to the Lease, and
Subtenant shall perform all obligations of Tenant under said Lease, with respect
to the Sublease Premises.

              2.     The Sublease shall terminate, unless sooner provided in the
Sublease, on the Lease Termination Date.

              3.     Sublessee shall comply strictly with the use and operation
provisions contained in Section 4 of the Lease. Any term of the Sublease that in
any way conflicts with or alters the provisions of the Lease shall be of no
effect as to Landlord and Landlord shall not assume any obligations as landlord
under the Sublease and neither Sublessor nor Sublessee shall acquire any rights
under the Sublease directly assertable against Landlord under the

<PAGE>   73
underlying Lease.

       4.  There shall be no further subleases of the Premises or the Subleased
Premises, without first obtaining the prior written consent of Landlord as
otherwise provided in the Lease.

       5.  Landlord's consent to the Sublease shall not (a) make Landlord a
party to the Sublease, (b) create any privity of contract between Landlord,
Sublessor or Sublessee or create any other contractual liability or duty on the
part of the Landlord to the Sublessor or Sublessee, (c) constitute its consent
or waiver of consent to any subsequent sublease or sub-sublease, (d) in any
manner increase, decrease or otherwise affect the rights and obligations of
Landlord and Tenant under the Lease, in respect of the Subleased Premises, or
(e) constitute a waiver or a release of Tenant of any convenant or obligation
contained in the Lease, in the event Landlord accepts or collects rent from
Sublessee.

       6.  In the event of a default under the Lease, Sublessor hereby assigns
to Landlord the rent due to Sublessor from Sublessee and hereby authorizes
Sublessee to pay said rent directly to Landlord, at Landlord's option.

        WITNESS, the signatures of the parties hereto:

                                        LANDLORD:

                                        THE EQUITABLE LIFE ASSURANCE
                                        SOCIETY OF THE UNITED STATES

                                        By:        /s/ BRENDA E. MCKINNEY
                                           ------------------------------------
                                        Name:        BRENDA E. MCKINNEY
                                             ----------------------------------
                                        Title:       INVESTMENT OFFICER
                                              ---------------------------------

                                        TENANT:    /s/ KEYVAN RAFEI
                                               --------------------------------
                                               Name: Keyvan Rafei

                                      -2-

<PAGE>   74

                                        SUBLESSOR:

                                        TENET HEALTHSYSTEMS MEDICAL, INC.

                                        By:          /s/ DOUGLAS E. RABEI
                                           ------------------------------------
                                        Name:          DOUGLAS E. RABEI
                                             ----------------------------------
                                        Title:           VICE PRESIDENT
                                              ---------------------------------

                                        SUBLESSEE

                                        CHOICEPOINT SERVICES, INC.

                                        By:          /s/ TOM KLESSER
                                           ------------------------------------
                                        Name:           TOM KLESSER
                                             ----------------------------------
                                        Title:  V.P. - FINANCE AND ACCOUNTING
                                              ---------------------------------

                                      -3-
<PAGE>   75
                        AMERICAN CENTER LEASE AGREEMENT

            MET LIFE INTERNATIONAL REAL ESTATE EQUITY SHARES, INC.,
                            A DELAWARE CORPORATION,

                                    LANDLORD

                                      AND

                    ADVANCED SWITCHING COMMUNICATIONS, INC.,
                            A DELAWARE CORPORATION,

                                     TENANT

                              8330 BOONE BOULEVARD
                                VIENNA, VIRGINIA

                               SEPTEMBER __, 1997

<PAGE>   76
                               TABLE OF CONTENTS

                                                                 PAGE
1.   Definitions ...............................................    1

2.   Lease Grant ...............................................    2

3.   Lease Term ................................................    2

4.   Base Rent .................................................    6

5.   Increases in Operating Expenses ...........................    6

6.   Additional Rent/Late Fees .................................    9

7.   Use .......................................................   10

8.   Services to be Furnished by Landlord ......................   10

9.   Improvements ..............................................   12

10.  Mechanic's Liens ..........................................   13

11.  Care of the Premises by Tenant ............................   13

12.  Repairs by Tenant .........................................   13

13.  Signage and Window Treatments .............................   14

14.  Use of Electrical Services by Tenant ......................   14

15.  Parking ...................................................   16

16.  Rules and Regulations .....................................   17

17.  Compliance with Laws ......................................   17

18.  Entry by Landlord .........................................   18

19.  Assignment and Subletting .................................   18

20.  Insurance .................................................   20

21.  Property Taxes ............................................   21

22.  Mutual Indemnification ....................................   21

23.  Casualty Damage ...........................................   23

24.  Condemnation ..............................................   24

25.  Damages from Certain Causes ...............................   24

26.  Events of Default/Remedies ................................   24

<PAGE>   77
<TABLE>
<S> <C>                                                                    <C>
27.  Bankruptcy of Tenant ................................................. 26

28.  Environmental Liability .............................................. 29

29.  Quiet Enjoyment ...................................................... 29

30.  Holding Over ......................................................... 29

31.  Subordination and Attornment ......................................... 29

32.  Landlord's Lien ...................................................... 32

33.  Attorney's Fees ...................................................... 32

34.  No Implied Waiver .................................................... 32

35.  Personal Liability ................................................... 33

36.  Security Deposit ..................................................... 33

37.  Financing Requirements ............................................... 35

38.  Estoppel Certificate ................................................. 35

39.  Certain Rights Reserved .............................................. 35

40.  Relocation ........................................................... 36

41.  Brokers .............................................................. 36

42.  Miscellaneous ........................................................ 36

     (a)  Entire Agreement ................................................ 36
     (b)  No Representations .............................................. 36
     (c)  Authority ....................................................... 36
     (d)  Notices ......................................................... 37
     (e)  Transfers By Landlord ........................................... 37
     (f)  Severability .................................................... 37
     (g)  Calendar Days/Business Days ..................................... 37
     (h)  Successors and Assigns .......................................... 37
     (i)  Recordation ..................................................... 37
     (j)  Force Majeure ................................................... 38
     (k)  Time of Performance ............................................. 38
     (l)  No Partnership .................................................. 38
     (m)  Effect of Delivery of This Lease ................................ 38
     (n)  Construction .................................................... 38
     (o)  Counterparts .................................................... 38
     (p)  Headings ........................................................ 38
     (q)  Exhibits ........................................................ 38
     (r)  Waiver of Jury Trial ............................................ 38
     (s)  Consent to Jurisdiction and Forum ............................... 39
     (t)  Governing Law ................................................... 39
</TABLE>

                                      -ii-
<PAGE>   78
                                    EXHIBITS

Exhibit A                     The Premises
Exhibit B                     Work Agreement
Exhibit B-1                   Space Plan and Construction Specifications
Exhibit B-2                   Schedule of Responsibilities
Exhibit C                     Declaration of Commencement Date
Exhibit D                     Rules & Regulations
Exhibit E                     Form of Letter of Credit

                                     -iii-

<PAGE>   79
                        AMERICAN CENTER LEASE AGREEMENT

     THIS DEED OF LEASE (the "Lease") is made and entered into as of the   day
of September, 1997, between MET LIFE INTERNATIONAL REAL ESTATE EQUITY SHARES,
INC., a Delaware corporation ("Landlord"), and ADVANCED SWITCHING
COMMUNICATIONS, INC., a Delaware corporation ("Tenant").

                                    RECITALS

     A.   Landlord is the owner of an office complex (the "Complex") known as
"American Center", located at 8300 and 8330 Boone Boulevard, Vienna, Virginia.

     B.   Tenant desires to lease certain space in the building located at 8330
Boone Boulevard (the "Building") in the Complex, and Landlord is willing to
lease such space to Tenant, upon the terms, conditions, covenants and
agreements set forth herein.

     NOW, THEREFORE, in consideration of the mutual promises herein contained
and other good and valuable consideration, the receipt and sufficiency of which
are hereby acknowledged, the parties hereto, intending legally to be bound,
hereby covenant and agree as follows.

                                   AGREEMENT

     1.   DEFINITIONS.

     (a)  "Premises" shall mean the space outlined on the floor plan attached
to this Lease as Exhibit A incorporated herein. The Premises are stipulated for
all purposes to contain approximately 20,914 square feet of "Net Rentable Area"
(as hereinafter defined) on the fifth floor of the Building; provided, however,
that Landlord may, upon completion of the Premises, cause precise measurements
of the Complex and the Premises to be made, and Base Rent (as hereinafter
defined) shall be adjusted upward or downward accordingly. The Premises will be
occupied in two phases: (i) approximately 13,262 square feet of Net Rentable
Area (the "Phase I Space") as shown on Exhibit A on the "Phase I Commencement
Date" (as hereinafter defined) and (ii) approximately 7,652 square feet of Net
Rentable Area (the "Phase II Space") as shown on Exhibit A on the "Phase II
Commencement Date" (as hereinafter defined).

     (b)  "Base Rent" shall mean the fixed rent paid monthly during the Lease
Term as provided in the following schedule, which schedule reflects an annual
rent for the first Lease Year based on Twenty-Six and 75/100 Dollars ($26.75)
per rentable square foot of Net Rentable Area of the Premises and annual
increases equal to three percent (3%) of the Net Base Rent in effect during the
immediately preceding Lease Year. As used herein, "Net Base Rent" is the product
of the Net Rentable Area times the difference between $26.75 and the amount per
square foot of the Operating Expenses for the Base Year. For example, if the
Operating Expenses for the Base Year are $7.50 per square foot, then the monthly
Net Base Rent would be $33,549.54 (i.e., $19.25 [$26.75 less $7.50] times 20,914
sq. ft. divided by 12). The monthly Base Rent for the First Lease Year will be
$46,620.79 (i.e., $26.75 times 20,914 sq. ft. divided by 12); however, such
amount shall be prorated until the Phase II Commencement Date since Tenant
<PAGE>   80
will be initially be occupying only the Phase I Space. The monthly Base Rent
for the second Lease Year would be $47,627.28, an increase of $1,006.49 (i.e.,
monthly Net Base Rent of $33,549.54 times 3%). The monthly Base Rent for the
third Lease Year would be $48,663.96, an increase of $1,036.68 (i.e., monthly
Net Base Rent in effect during the immediately preceding Lease Year of
$34,556.03 [$33,549.54 plus $1,006.49] times 3%).

     (c)  "Phase I Commencement Date" and the "Phase II Commencement Date"
shall mean the dates determined in accordance with Section 3 hereof.

     (d)  "Lease Term" shall mean a term commencing on the Phase I Commencement
Date and continuing until ninety-six (96) calendar months after the first day
of the first full month following the Phase I Commencement Date.

     (e)  "Lease Year" shall mean that period beginning on the Phase I
Commencement Date and terminating on the last day of the twelfth (12th) full
calendar month thereafter, and each succeeding period of twelve (12) full
calendar months during the entire Lease Term.

     (f)  "Operating Expenses" shall mean the expenses described in Section
(5(b) of this Lease.

     (g)  "Base Year" shall mean the 1998 calendar year for purposes of
determining increases in Operating Expenses pursuant to Section 5 of this Lease.

     (h)  "Security Deposit" shall mean the sum of One Million and no/100
dollars ($1,000,000.00) in the form of a letter of credit or cash. The Security
Deposit has been deposited with Landlord by Tenant within 12 business days of
the execution hereof.

     (i)  "Common Areas" shall mean those areas devoted to lobbies, corridors,
all elevator foyers, restrooms, mechanical rooms, janitorial closets,
electrical and telephone closets, vending areas and other similar facilities
provided for the common use or benefit of tenants generally and/or the public.

     (j)  "Service Area" shall mean those areas within the outside walls of the
Complex used for elevator mechanical rooms, building stairs, fire towers,
elevator shafts, flues, vents, stacks, pipe shafts, and vertical ducts (but
shall not include any such areas for the exclusive use of the particular
Tenant).

     (k)  "Net Rentable Area" of the Premises shall mean the gross area within
the inside surface of the outer glass or other material comprising the exterior
walls of the Premises, to the mid-point of any walls separating portions of the
Premises from those of adjacent tenants and to the Common Area or Service Area
side of walls separating the Premises from Common Areas and Service Areas,
subject to the following:

          (1)  Net Rentable Area shall not include any Service Areas.

                                       2
<PAGE>   81
          (2)  Net Rentable Area shall include a pro rata part of the Common
Areas on the floor on which the Premises are located, such proration based upon
the ratio of the Net Rentable Area within the Premises to the total Net Rentable
Area on such floor, both determined without regard to the Common Areas. The
Common Area on floor(s) upon which the Premises are located shall never exceed
2,735 square feet and may be adjusted as determined by Landlord from time to
time to confirm such allocation to changes in the configuration of rented spaces
and Common Areas upon such floor.

          (3)  Net Rentable Area shall include any columns and/or projection(s)
which protrude into the Premises and/or the Common Areas.

     (l) "Exterior Common Areas" shall mean those areas of the Complex which
are not located within the buildings comprising the Complex and which are
provided and maintained for the common use and benefit of Landlord and tenants
of the Complex generally and the employees, invitees and licensees of Landlord
and such tenants; including without limitation all parking areas, enclosed or
otherwise; all streets, sidewalks and landscaped areas located within the
Complex.

     (m)  "Event of Default" shall have the meaning assigned thereto in Section
26 of this Lease.

     2.  LEASE GRANT.  Subject to and upon the terms herein set forth, Landlord
leases to Tenant, and Tenant leases from Landlord, the Premises. The lease of
the Premises includes the right, together with other tenants of the Complex and
members of the public, to use the Common Areas of the Building and the Exterior
Common Areas of the Complex, but includes no other rights not specifically set
forth herein. Landlord reserves the right to modify the size, location,
arrangement, finish and other features of the Common Areas and the Exterior
Common Areas.

     3.  LEASE TERM.

     (a) The Lease Term shall commence on the Phase I Commencement Date and
shall continue until the expiration of the Lease Term unless this Lease is
terminated earlier or extended in accordance with the provisions of this Lease.

     (b) The Phase I Commencement Date shall be the date on which Landlord
substantially completes construction of the tenant improvements in the Phase I
Space, as determined pursuant to Section 5 of Exhibit B attached hereto and
made a part hereof, or the date on which Tenant commences beneficial use of the
Phase I Space, whichever date occurs first. The Phase II Commencement Date
shall be the date on which Landlord substantially completes construction of the
tenant improvements in the Phase II Space, as determined pursuant to Section 5
of Exhibit B attached hereto and made a part hereof, or the date on which
Tenant commences beneficial use of the Phase II Space, whichever date occurs
first. Tenant shall be deemed to have commenced beneficial use of the Phase I
Space or the Phase II Space when

                                       3

<PAGE>   82
Tenant begins to move furniture and furnishings into the such space, and such
beneficial use shall be deemed to be an acceptance of the nature and
sufficiency of any tenant improvements to be made by Landlord with respect to
the Phase I Space and the Phase II Space. Notwithstanding the foregoing, if
Landlord is delayed in completing construction of the tenant improvements in
the Phase I Space or the Phase II Space as a result of any of the reasons
described in Exhibit B, then the Phase I Commencement Date or the Phase II
Commencement Date shall be the date determined in accordance with Section 7(f)
of Exhibit B.

     (c)  Promptly after the Phase I Commencement Date and the Phase II
Commencement Date have been determined, Landlord and Tenant agree to execute a
written declaration in the form attached hereto as Exhibit C setting forth the
Phase I Commencement Date and the Phase II Commencement Date, as applicable,
and the date upon which the Lease Term will expire. Failure to sign said
written declaration shall not affect the commencement or expiration of the
Lease Term.

     (d)  It is presently anticipated that the Phase I Space will be ready for
occupancy by Tenant on or about December 1, 1997, and that the Phase II Space
will be ready for occupancy by Tenant on or about December 1, 1998. If Landlord
is unable to complete construction of the tenant improvements in, or otherwise
deliver possession of, the Phase I Space or the Phase II Space by such dates,
Landlord's liability to Tenant on account of Landlord's inability to deliver
possession thereof to Tenant shall be limited to the amount specified in
Section 7(g) of Exhibit B, and this Lease shall not be rendered void or
voidable as a result of such delay. If the tenant improvements have not been
substantially completed by the date referred to above due to omission, delay or
default by Tenant or anyone acting under or for Tenant, Landlord shall have no
liability because of such delays, and the obligations of this Lease (including,
without limitation, the obligation to pay rent) shall nonetheless commence as
of the Phase I Commencement Date or the Phase II Commencement Date as
applicable.

     (e)  Landlord shall have no obligation to deliver possession of the Phase
I Space or the Phase II Space to Tenant, and Tenant shall have no obligation to
accept delivery of the Phase I Space or the Phase II Space from Landlord,
before the Phase I Commencement Date or the Phase II Commencement Date, as
applicable.

     (f)  Subject to the provisions of this subsection (f), Tenant shall have,
and is hereby granted, an option to renew or extend the Lease Term for the
entire Premises for one (1) additional period of sixty (60) months (such
additional period being hereinafter referred to as the "Renewal Term").

          i)  This renewal option shall be exercisable by Tenant by giving
written notice to Landlord of Tenant's intention to exercise such renewal
option not more than fourteen (14) months but no later than nine (9) months
before the expiration of the initial Lease Term. If Tenant shall fail to
exercise the renewal option at the time and in the manner hereinabove provided
or should Tenant fail to execute an addendum to this Lease within thirty (30)
days of the determination

                                       4
<PAGE>   83
of the Market Rent (as hereinafter defined), this option shall be rendered void
and of no force or effect, and Tenant shall have no further right to extend or
renew the Lease Term.

     ii)  The Base Rent payable during the Renewal Term shall be at the then
current Market Rent as of the commencement of such Renewal Term. As used
herein, "Market Rent" shall be the Base Rent for space of equivalent quality,
size, utility and location, with the length of the Renewal Term and
credit-standing of Tenant as well as the amount of Tenant concessions being
offered for comparable first-class office buildings in the Tyson's Corner area
and the operating cost reimbursements and escalations to be taken into account.
If Landlord and Tenant do not agree on the then current Market Rent for the
Renewal Term within thirty (30) days following Landlord's receipt of Tenant's
notice of its intent to exercise its option to renew, the Market Rent shall be
determined as follows:

     The Market Rent shall be determined by a group of three (3) real estate
     brokers, one of whom shall be named by Landlord, one by Tenant, and the two
     so appointed shall select a third. Said brokers shall each be licensed in
     Virginia as real estate brokers specializing in the field of commercial
     leasing, having at least five (5) years' experience, and recognized as
     ethical and reputable within their field. Landlord and Tenant agree to make
     their appointments promptly within ten (10) days following the expiration
     of the aforementioned thirty (30) day period. The two brokers selected by
     Landlord and Tenant shall promptly select a third broker. If the two
     brokers are unable to agree upon a third broker within five (5) days after
     they have both accepted their appointment, the parties shall ask the
     Northern Virginia Association of Realtors to appoint such third broker.
     Within five (5) days after the third broker is selected, they shall submit
     their determination of the Market Rent. The Market Rent shall be the mean
     of the two closest determinations and shall be binding on Landlord and
     Tenant. Landlord and Tenant shall pay the costs and expenses of the broker
     selected by each of them and shall share equally the costs and expenses of
     the third broker.

     iii) All references in this Lease to the Lease Term shall be construed to
mean both the initial Lease Term and the Renewal Term, if Tenant has exercised
its option and the Renewal Term commences, unless the context clearly indicates
that another meaning is intended.

     iv)  The renewal option may not be exercised by Tenant, if at the time
specified for exercising such option and/or at the date such Renewal Term is to

                                       5
<PAGE>   84
begin, (i) this Lease shall not be in full force and effect, (ii) Tenant shall
not be in actual possession of the entire Premises, or (iii) an Event of Default
shall have occurred and remain uncured under this Lease. If Tenant shall not be
entitled to exercise such option to renew because of the foregoing provisions of
this subsection, such option shall be rendered void and of no force and effect.
It is understood that this renewal option is personal to Tenant and will not
benefit any subtenant of the Premises or any assignee of this Lease whether or
not Landlord has approved such sublease or assignment.

     4.   BASE RENT.

     Tenant shall pay to Landlord at Landlord's address provided herein (or such
other address as may be designated by Landlord in writing from time to time) the
Base Rent for the Premises, without setoff, deduction or demand. The Base Rent
shall be payable on the Phase I Commencement Date and thereafter monthly, in
advance, on the first day of each and every month during the Lease Term. Base
Rent for any portion of a month shall be prorated at the rate of one-thirtieth
(1/30th) of the Base Rent for each day. Landlord shall abate twenty (20) days of
the Base Rent due on the Phase I Space.

     5.   INCREASES IN OPERATING EXPENSES.

     (a)  Commencing on January 1, 1999, Tenant shall pay to Landlord its
proportionate share of the amount by which the Operating Expenses (as
hereinafter defined) incurred by Landlord in the operation of the Complex during
each calendar year exceed the actual Operating Expenses for the Base Year,
calculated as the amount of such increase per square foot of Net Rentable Area
in the Complex. Operating Expenses shall be grossed up to reflect an occupancy
level of ninety-five percent (95%) within the Complex. Since a portion of the
Complex is dedicated to retail uses which do not require many of the services
provided to the office tenants, adjustments in the per-square-foot calculation
of the Operating Expenses shall be made to allocate office Operating Expenses
among the office tenants in the Complex and the other Operating Expenses
chargeable to office and retail tenants among all tenants in the Complex. The
allocation of office Operating Expenses shall be adjusted appropriately in the
event of changes in either the amount of total Net Rentable Area in the Complex
or the amount of office or retail area in the Complex.

     (b)  Operating Expenses are the sum of the following costs and expenses
which in each instance shall be reasonable in amount and of a nature normally
incurred by owners or managers of comparable first-class buildings in the
Tyson's Corner, Virginia area: (i) Real Estate Taxes (as hereinafter defined);
(ii) gas, water, sewer, electricity and other utility charges (including
surcharges) of every type and nature; (iii) insurance; (iv) personnel costs,
including,

                                       6
<PAGE>   85
but not limited to salaries, wages, fringe benefits and other direct and
indirect costs of engineers, superintendents, porters, and other building
personnel not above the level of building manager; (v) costs of all materials,
supplies, labor and other services purchased or levied in connection with the
Complex, including but not limited to, service and maintenance contracts for
chillers, boilers, controls, elevators, windows, janitorial and general
cleaning, and security services; (vi) all other maintenance, repair,
replacement expenses and supplies which are deducted by Landlord in computing
its federal income tax liability; (vii) costs of landscaping, gardening and
planting, cleaning, painting (including striping of parking areas), decorating,
lighting, sanitary control, removal of trash, garbage and other refuse; (viii)
lighting, heating, ventilating and air conditioning of the Complex; (ix) fire
protection; (x) compliance with governmental laws, statutes, regulations and
orders; (xi) management fees; (xii) installing and renting of signs; (xiii)
amortization of capital expenditures made by Landlord during the Lease Term to
reduce Operating Expenses (but only to the extent Operating Expenses are
actually reduced) or to comply with governmental laws, statutes, regulations
and orders; (xiv) any other costs and expenses incurred by Landlord in the
operation of the Complex; and (xv) the costs of any additional services not
provided to the Complex at the Commencement Date but thereafter provided by
Landlord in the prudent management or operation of the Complex. Notwithstanding
anything to the contrary in this Lease, Operating Expenses shall not include
(i) principal or interest payments on any mortgages or deeds of trust; (ii)
depreciation of capital improvements; (iii) amortization of capital
improvements, except as provided above; (iv) the costs of special services,
utilities, and tenant improvement allowances separately chargeable to
individual tenants of the Complex whether or not such costs are reimbursed to
Landlord; (v) expenses associated with leasing space in the Complex or the sale
of any interest in the Complex, including, without limitation, advertising and
marketing, commissions and amounts paid for or on behalf of an individual
tenant such as space planning, moving costs, and rent, improvement and other
concessions; (vi) original construction costs of the Complex; (vii) the costs
of any repair or replacement by reason of a casualty, condemnation, or warranty
claim to the extent Landlord is reimbursed by insurance, condemnation, or
warranty proceeds; (viii) any amount paid to an affiliate (i.e., an entity that
is subject to "control" by the same entity or entities as Landlord), parent or
subsidiary of Landlord, unless the amount paid is a standard "arms length"
price for the type of service rendered; (ix) compensation paid to officers or
executives of Landlord or its management agent other than the management fee;
(x) costs, fines, interest, penalties, legal fees, or other expenses incurred
due to Landlord's violation of any rule or law or the late payment of taxes,
utility bills or other obligations; (xi) Landlord's general corporate overhead
and general administrative expenses; (xii) ground rents; (xiii) costs of
selling, syndicating, financing, mortgaging, or hypothecating any part of or
interest in the Complex; (xiv) reserves for repairs, maintenance and
replacements; or (xv) costs of services provided solely to retail tenants in
the Complex (whether or not such costs are reimbursed to Landlord). In the
event engineers or other personnel delivering services to the Complex are also
assigned to other buildings, the Operating Expenses attributable to their
services shall be based on the reasonable allocation of their services to the
Complex. Management fees shall not exceed the rate customarily charged by
management companies for comparable first-class office buildings in the Tyson's
Corner area. In addition, the rent for space in the Complex used by Landlord's
management company shall

                                       7
<PAGE>   86
not exceed the fair market value of such space, and no more than 1,600 square
feet of Net Rentable Area of such space shall be included in Operating Expenses.

     (c)  Real Estate Taxes shall mean (i) all real estate taxes, including
general and special assessments, if any, which are imposed upon Landlord or
assessed against the Complex and (ii) any other present or future taxes or
governmental charges that are imposed upon Landlord or assessed against the
Complex or the equipment, fixtures, or other property therein which taxes or
charges are in the nature of, in addition to, or in substitution for real
estate taxes, including, without limitation, any license fees, business
improvement district fees of any quasi-governmental organization, tax measured
by or imposed upon rents, or other tax or charge upon Landlord's business of
leasing the Complex, but shall not include any federal, state or local income
tax. Real Estate Taxes shall also include all expenses incurred by Landlord in
obtaining or attempting to obtain a reduction of Real Estate Taxes, including,
but not limited to, legal fees.

     (d)  For each calendar year during the Lease Term, Landlord shall submit
to Tenant a statement setting forth Landlord's reasonable estimate of the
amount Tenant will be obligated to pay pursuant to this Section for the
calendar year in question, which reasonable estimate may be revised from time
to time. Tenant shall pay to Landlord on the first day of each month following
receipt of such statement during such calendar year an amount equal to such
estimated amount multiplied by a fraction, the numerator of which is 1, and the
denominator of which is the number of months during such calendar year which
fall within the Lease Term and follow the date of the foregoing statement.
Within ninety (90) days after the expiration of such calendar year, Landlord
shall submit to Tenant a statement showing Tenant's proportionate share of the
increase in the Operating Expenses incurred during such calendar year and the
aggregate amount of the estimated payments made by Tenant on account thereof.
If the aggregate amount of such estimated payments exceeds Tenant's actual
liability for such increase, Tenant shall deduct the net overpayment from its
next monthly payment of Base Rent and additional rent on account of estimated
future increases in the Operating Expenses. If Tenant's actual liability for
such increase exceeds the estimated payments made by Tenant on account thereof,
then Tenant shall immediately pay to Landlord the total amount of such
deficiency.

     (e) In the event the Lease Term commences or expires during a calendar
year, the increase in the Operating Expenses to be paid by Tenant for such
calendar year shall be determined by multiplying the amount of Tenant's
proportionate share thereof for the full calendar year by a fraction, the
numerator of which is the number of days during such calendar year falling
within the Lease Term, and the denominator of which is 365. Tenant's liability
for its proportionate share of the increase in the Operating Expenses for the
last calendar year falling entirely or partly within the Lease Term shall
survive the expiration of the Lease Term and shall be payable as provided in
this Section.

     (f) Provided no Event of Default has occurred and in continuing, Tenant
shall have the right, at Tenant's expense, to audit Landlord's books and
records of the Operating Expenses relating to any calendar year for which
payments of increases in Operating Expenses are due from Tenant as additional
rent. No subtenant shall have any right to conduct an audit, and no

                                       8

<PAGE>   87
assignee shall conduct an audit for any period during which such assignee was
not in possession of the Premises. Tenant shall provide written notice for such
audit within thirty (30) days following the date that Landlord or its agent
shall have delivered to Tenant the statement of Operating Expenses with respect
to which Tenant desires to make such audit. Such audit shall cover only the
immediately preceding calendar year for the statement being audited and shall
be conducted by an independent certified public accountant at the offices of
Landlord's managing agent or accountant during normal business hours at a time
mutually convenient to Landlord and Tenant. If Landlord's managing agent or
accountant does not have offices in the Washington, D.C. metropolitan area,
the books and records will be made available to Tenant at a mutually agreed
location in such local area. If the audit for such calendar year reasonably
suggests errors in the preceding calendar year, Landlord shall provide the
books and records for such preceding year, but in no event shall Landlord be
required to provide books and records for more than a total of the three (3)
calendar years immediately preceding the calendar year in which the audit
request is made. In no event shall the accountant be compensated on the basis
of a contingent fee arrangement. Landlord may require as a condition of
permitting such audit that Tenant, its principals, employees, and accountants
enter into a confidentiality agreement reasonably acceptable to Landlord. Such
audit shall be conducted in accordance with generally accepted auditing
standards of the AICPA. Tenant shall deliver to Landlord a copy of the results
of such audit within five (5) days of its receipt by Tenant. If Tenant's audit
reveals that Landlord's calculation of additional rent is in error, the
corrected amount shall be paid by Tenant to Landlord within ten (10) days after
the completion of the audit, or if Tenant has already paid the additional rent,
the overpayment will be promptly refunded to Tenant or credited to the next
payment of rent due under this Lease. Notwithstanding anything to the contrary
in this Section, in the event that any such audit reveals that Landlord's
calculation of Operating Expenses was inaccurate by three percent (3%) or more
per calendar year, Landlord, not Tenant, shall pay for the reasonable audit
expenses incurred by Tenant up to Seven Thousand and no/100 Dollars ($7,000.00)
provided Tenant presents to Landlord detailed statements and paid receipts for
such services. Landlord shall pay said expenses within thirty (30) days of
Landlord's receipt of the documentation required under this subsection (f).

     6.   ADDITIONAL RENT/LATE FEES. All payments required to be made by Tenant
pursuant to this Lease shall be deemed rent for the Premises, whether or not
expressly characterized as rent, the nonpayment of which shall entitle Landlord
to exercise all such rights and remedies as are herein provided in the case of
the nonpayment of Base Rent. Notwithstanding any dispute which may arise in
connection with the computation or estimate of any amount due under this Lease,
Tenant shall be obligated to pay the amount specified by Landlord without
set-off or deduction pending the resolution of any dispute. The agreements of
Tenant to pay Base Rent, increases in Operating Expenses, and other charges
pursuant to this Lease constitute covenants of Tenant, which covenants are
independent of all other covenants or obligations of either party hereunder,
and Tenant hereby irrevocably waives any claim or defense of offset, deduction,
withholding, and waives any notice or demand in excess of notices otherwise
provided in this Lease, with respect to the performance (or default in
performance) of Tenant's covenants to pay Base Rent and such other charges. In
the event any installment of rent is not paid within five (5) days of the date
when due and payable (regardless of any

                                       9

<PAGE>   88
notice period provided in Section 26(a)(i) of this Lease), Tenant shall pay a
late charge of four percent (4%) of the delinquent amount.

     7.   USE. Tenant shall use and occupy the Premises solely for general
office purposes and incidental purposes specifically related to the computer and
telecommunications business conducted by Tenant provided such uses do not
violate Section 17 of this Lease and for no other use or purpose without the
prior written consent of Landlord. Tenant represents and warrants that it is
not, and will not operate the Premises as, a place of public accommodation for
the purposes of the Americans with Disabilities Act (the "ADA"), as it may be
amended from time to time. Tenant shall not use or occupy the Premises for any
unlawful purpose or in any manner that will constitute waste, nuisance or
unreasonable annoyance to Landlord or other tenants of the Complex or for any
purpose prohibited in the rules and regulations promulgated by Landlord. Tenant
acknowledges that a use which attracts a large number of people, such as an
employment agency or public defender's office, would cause unreasonable
annoyance to Landlord. If any present or future law, ordinance, regulation or
order requires an occupancy permit for the Premises, Tenant will obtain such
permit at Tenant's own expense.

     8.   SERVICES TO BE FURNISHED BY LANDLORD.

     (a)  Landlord agrees to furnish Tenant the following services;

          i)   Hot and cold water at those points of supply provided for
general use of other tenants in the Complex and any pantry included within the
Premises, central heat and air conditioning in season, at such temperatures and
in such amounts as are considered by Landlord to be standard or as required by
governmental authority; provided, however, heating and air conditioning service
at times other than for Normal Business Hours (as hereinafter defined) shall be
furnished only upon Tenant's written request to Landlord prior to 3:00 p.m. at
least one (1) business day in advance of the date such usage is requested. As
used herein, Normal Business Hours shall be 7:30 a.m. to 6:00 p.m. on Mondays
through Fridays and 8:00 a.m. to 1:00 p.m. on Saturdays, exclusive of Normal
Business Holidays (as hereinafter defined). As used herein, Normal Business
Holidays shall include Sundays and all legal holidays specified in the rules and
regulations for the Complex. Tenant shall bear the entire cost of additional
service allocable to the Premises as such costs are determined and allocated by
Landlord from time to time.

          ii)  Routine maintenance and electrical lighting service for all
Exterior Common Areas and Service Areas in the manner and to the extent deemed
by Landlord to be standard.

          iii) Janitor service, Mondays through Fridays, exclusive of Normal
Business Holidays; provided, however, if Tenant's floor covering or other
improvements require special treatment, Tenant shall pay the additional cleaning

                                       10

<PAGE>   89
     cost attributable thereto as additional rent upon presentation of a
     statement therefor by Landlord. Tenant shall cooperate with Landlord's
     employees in the furnishing by Landlord of janitorial services at such
     times (including Normal Business Hours) as Landlord elects to have the
     necessary work performed; provided, however, that janitorial services
     performed by Landlord during Normal Business Hours shall be performed in
     such a manner as to not unreasonably interfere with Tenant's use of the
     Premises.

          iv)  Subject to the provisions of the Section captioned "Use of
     Electrical Services by Tenant", facilities to provide all electrical
     current required by Tenant in its use and occupancy of the Premises.

          v)  All standard fluorescent bulb replacement in the Premises and
     fluorescent and incandescent bulb replacement in the Common Areas and
     Service Areas.

          vi)  Landlord shall provide card key access to the Complex during
     periods other than Normal Business Hours, and Tenant shall cooperate with
     Landlord in limiting the use of card keys to persons authorized by Tenant
     to enter the Complex. Landlord, however, shall have no liability to Tenant,
     its employees, agents, invitees or licensees for losses due to theft or
     burglary, or for damages done by unauthorized persons on the Premises, nor
     shall Landlord be required to insure against any such losses. Tenant shall
     cooperate fully in Landlord's efforts to maintain security in the Complex
     and shall follow all rules and regulations promulgated by Landlord with
     respect thereto.

     (b)  The failure by Landlord to any extent to furnish or the interruption
or termination of these defined services in whole or in part, resulting from
causes beyond the reasonable control of Landlord shall not render Landlord
liable in any respect nor be construed as an eviction of Tenant, nor work an
abatement of rent, nor relieve Tenant from the obligation to fulfill any
covenant or agreement hereof. Should any of the equipment or machinery used in
the provision of such services for any cause cease to function properly, Tenant
shall have no claim for offset or abatement of rent or damages on account of an
interruption in service occasioned thereby or resulting therefrom.
Notwithstanding the foregoing, in the event there shall be an interruption or
cessation of the Building's elevator service, electricity service, or HVAC
service in the manner required to be provided by Landlord under this Lease,
which shall materially interfere with Tenant's use and enjoyment of all or
substantially all of the Premises (a "Service Interruption"), and (i) if such
Service Interruption shall continue for at least ten (10) consecutive business
days following receipt by Landlord of written notice from Tenant describing
such Service Interruption (the "Service Interruption Notice"), (ii) if such
Service Interruption shall not have been caused, in whole or in part, by any
act, omission or negligence of Tenant or of Tenant's agents, employees,
contractors or visitors, and (iii) if such Service Interruption shall not have
been caused in whole or in part by a fire or other casualty or an event of
force majeure as described in Section 42(j) of this Lease (a Service
Interruption that satisfies all of the

                                       11
<PAGE>   90
foregoing conditions being referred to hereinafter as a "Material Service
Interruption"), then as Tenant's sole and exclusive remedy in connection with
such Material Service Interruption, Landlord shall abate the Base Rent and all
additional rent in the same proportion as the portion of the Premises affected
by the Material Service Interruption bears to the entire Premises for the
period which shall begin on the commencement of such Material Service
Interruption and which shall end on the day such Material Service Interruption
shall cease. Landlord, however, shall have no obligation to provide such an
abatement if Tenant's personnel are occupying the Premises or the affected
portion thereof during the period of the Material Service Interruption.

     9.   IMPROVEMENTS.

     (a)  Tenant has inspected the Premises and accepts the Premises "as is".
Landlord will not make, and is under no obligation to make, any structural or
other alterations, decorations, additions or improvements in or to the Premises
except as set forth in Exhibit B or as otherwise provided in this Lease. All
installations and improvements now or hereafter placed on the Premises shall be
for Tenant's account and at Tenant's cost (and Tenant shall pay ad valorem
taxes and increased insurance thereon or attributable thereto), which cost
shall be payable by Tenant to Landlord in advance as additional rent.

     (b)  Tenant will not make or permit anyone to make any alterations,
decorations, additions or improvements, structural or otherwise, in or to the
Premises or the Complex, without the prior written consent of Landlord, which
consent shall not be unreasonably withheld or delayed. When granting its
consent, Landlord may impose any reasonable conditions it deems appropriate,
including, without limitation, the approval of plans and specifications,
approval of the contractor or other persons to perform the work, and the
obtaining of specified insurance. All improvements permitted by Landlord must be
performed by bonded contractors and must conform to all rules and regulations
established from time to time by the Board of Fire Underwriters having
jurisdiction or similar body exercising similar functions and to all laws,
regulations and requirements of the federal, Virginia and Fairfax County
governments. Tenant shall obtain and deliver to Landlord written unconditional
waivers or releases of mechanic's and materialmen's liens against the Complex
and the land upon which it is situated from all contractors, subcontractors,
architects, engineers, laborers and material suppliers for all work, labor and
services performed and materials furnished in connection with improvements to
the Premises. Any alterations, decorations, additions or improvements to the
Premises, other than those made by Landlord pursuant to Exhibit B, shall be
conducted on behalf of Tenant and not on behalf of Landlord, and Tenant shall
not be deemed to be the agent of Landlord. In the event Landlord shall give its
written consent to the making of any improvements to the Premises, such written
consent shall not be deemed to be an agreement or consent by Landlord to subject
its interest in the Premises, the Complex, or the land upon which it is situated
to any mechanic's or materialmen's liens which may be filed in connection
therewith. Tenant shall supply Landlord with as-built plans showing all
improvements by Tenant to the Premises or the Complex promptly upon completion
of each such improvement. Except as otherwise expressly provided in this Lease,
Landlord shall not be required to make any repairs to the Premises.

                                       12
<PAGE>   91
     10. MECHANIC'S LIENS. Tenant will not suffer or permit any mechanic's lien
or liens to be placed upon the Premises or the Complex arising out of any work
contracted for or authorized by Tenant in respect to the Premises. Nothing in
this Lease shall be deemed or construed in any way as constituting the consent
or request of Landlord, express or implied, by inference or otherwise, to any
person for the performance of any labor or the furnishing of any materials to
the Premises, or any part thereof, nor as giving Tenant any right, power, or
authority to contract for or permit the rendering of any services or the
furnishing of any materials that would give rise to any mechanics' or other
liens against the Premises. In the event any such lien is attached to the
Complex or Tenant's interest in the Premises, Tenant shall immediately cause
same to be released or bonded off, and if Tenant fails to do so, then, in
addition to any other right or remedy of Landlord, Landlord may, but shall not
be obligated to, discharge the same. Any costs and expenses incurred by Landlord
for any of the aforesaid purposes shall be paid by Tenant to Landlord on demand
as additional rent.

     11. CARE OF THE PREMISES BY TENANT. Tenant agrees not to commit or allow
any waste to be committed on any portion of the Premises and at the termination
of this Lease to deliver up the Premises to Landlord in as good condition as at
the date of the commencement of the Lease Term, ordinary wear and tear and
insured casualty losses excepted. Tenant shall not install any equipment of any
type or nature that will or may necessitate any changes, replacements or
additions to, or in the use of, the water system, heating system, plumbing
system, air-conditioning system or electrical system of the Premises or the
Complex, without first obtaining the prior written consent of Landlord. Business
machines and mechanical equipment belonging to Tenant which cause noise or
vibration that may be transmitted to the structure of the Complex or to any
space therein to such a degree as to be objectionable to Landlord or to any
tenant in the Complex shall be installed and maintained by Tenant, at Tenant's
expense, on vibration eliminators or other devices sufficient to reduce such
noise and vibration to a level satisfactory to Landlord.

     12. REPAIRS BY TENANT. Tenant covenants and agrees with Landlord, at
Tenant's own cost and expense, to repair or replace any damage done to the
Premises or the Complex, or any part thereof, caused by Tenant or Tenant's
agents, employees, or invitees. Such repairs shall restore the Premises or the
Complex to the condition existing prior to such damage and shall be effected in
compliance with all applicable laws; provided, however, if Tenant fails to make
such repairs or replacements promptly, Landlord may, at its option, make
repairs or replacements, and Tenant shall pay the cost thereof to Landlord on
demand as additional rent. All improvements to the Premises or the Complex made
by either party shall immediately become the property of Landlord and shall
remain upon and be surrendered with the Premises as a part thereof at the end
of the Lease Term. Notwithstanding the foregoing, (i) if Tenant is not in
default under this Lease, Tenant shall have the right to remove, prior to the
expiration of the Lease Term, all movable furniture, furnishings and equipment
installed in the Premises solely at the expense of Tenant and (ii) Landlord
shall have the right to require Tenant, at the end of the Lease Term, to remove
all tenant improvements and fixtures installed by Tenant in the Phase I Space
and the Phase II Space after the Phase I Commencement Date and the Phase II
Commencement, respectively, at the sole cost of Tenant. Notwithstanding the
foregoing, if

                                       13
<PAGE>   92
Tenant so requests. Landlord will state in writing at the time of Landlord's
approval of Tenant's proposed improvements to the Premises, which improvements
Landlord will not require Tenant to remove at the expiration or earlier
termination of this Lease. In the event that Landlord elects to require Tenant
to remove improvements installed by Tenant, and Tenant fails to remove such
improvements, Landlord may remove them at Tenant's cost, and Tenant shall pay
Landlord on demand the cost of restoring the Premises to their condition prior
to the installation of such improvements.

     13. SIGNAGE AND WINDOW TREATMENTS.

     (a) No sign, advertisement or notice referring to Tenant shall be
inscribed, painted, affixed or otherwise displayed on any part of the exterior
or the interior of the Complex except on the directories and the doors of
offices and such other areas as are designated by Landlord, and then only in
such place, number, size, color and style as are approved by Landlord. All of
Tenant's signs that are approved by Landlord shall be installed by Landlord at
Tenant's cost and expense. Tenant shall reimburse Landlord for such amount upon
written demand from Landlord and such sum shall be considered additional rent
hereunder. The color and fabric of the lining of all drapes (or if unlined, the
draperies themselves) which Tenant desires to place on exterior windows or
openings of the Building must be approved by Landlord prior to the
installation thereof so that a uniform color and appearance may be preserved
from the exterior of the Complex. Landlord agrees to furnish a directory of the
names and locations of its tenants and to install and maintain the same at a
convenient location in the lobby of each building in the Complex. The initial
listing of the name and room number of Tenant shall be furnished without
charge. The listings of additional names or room numbers and changes or
revisions of listings shall be made by Landlord at the cost of Tenant. If any
sign, advertisement or notice that has not been approved by Landlord is
exhibited or installed by Tenant, Landlord shall have the right to remove the
same at Tenant's expense. Landlord reserves the right to affix, install and
display signs, advertisements and notices on any part of the exterior or
interior of the Complex except the Premises.

     (b) Subject to the rights of Rafie and Associates/The Guardian ("Rafie"), a
tenant in the Building, Tenant shall have the nonexclusive right to install an
exterior sign on the top spandrel of the Building provided (i) Tenant expands
the Premises in the Building to a size larger than 20,914 square feet of Net
Rentable Area and (ii) Tenant is leasing and is actually occupying the largest
amount of Net Rentable Area in the Building. For purposes of this subsection
(b), in determining the amount of square feet of Net Rentable Area leased by
Tenant in the Building, no portion of the Premises subject to an assignment or
sublet will be included. The location and specification of said sign or any
changes thereto after the sign is installed are subject to Landlord's prior
written consent, it being understood that Landlord may withhold its consent if
in Landlord's judgment, such sign is aesthetically inconsistent with the
character of the Complex. The sign must be no longer than one hundred fifteen
(115) feet with letters not exceeding four (4) feet in height. If at any time
Tenant no longer satisfies the criteria in subsections (i) and (ii) above,
Landlord may require Tenant to remove the exterior sign at Tenant's sole cost
and expense. Any sign installed pursuant to this subsection (b) shall be
installed and maintained and,

                                       14
<PAGE>   93
upon the expiration or earlier termination of this Lease, shall be removed, at
Tenant's sole cost and expense. Upon the removal of the sign, Tenant shall
restore the Building to the condition that existed prior to the installation of
the sign. The sign shall comply with all applicable laws and ordinances, and
any permits therefor shall be obtained by Tenant at Tenant's expense.

     (c) In the event Landlord offers any tenant (other than Rafie) occupying a
single floor or less in the Building the right to install an exterior sign on
the top spandrel of the Building, Landlord shall first give Tenant written
notice of such offer, and if Tenant does not then satisfy criteria (i) and (ii)
in subsection (b) above and has not assigned or sublet any portion of the
Premises, Tenant shall have the prior right to install such a sign provided
Tenant gives Landlord written notice no later than five (5) business days
after Tenant's receipt of Landlord's notice. If Tenant does not install its
sign within one hundred twenty (120) days after exercising its right to do so,
Landlord may offer the exterior signage right to any other tenants in the
Building and Tenant's rights under this subsection (c) shall be of no further
force and effect. Landlord will provide good faith responses to Tenant's
requests regarding the rights of other tenants occupying a single floor or less
to install a sign on the spandrel.

     14. USE OF ELECTRICAL SERVICES BY TENANT. Tenant's use of electrical
services furnished by Landlord shall be subject to the following:

          i)   Tenant's electrical equipment shall be restricted to that
     equipment which individually does not have a rated capacity greater than .5
     kilowatts per hour and/or require voltage other than 120/208 volts, single
     phase. Collectively, Tenant's equipment shall not have an electrical design
     load greater than an average of 2 watts per square foot.

          ii)  Tenant's lighting shall not have a design load greater than an
     average of 2 watts per square foot.

          iii) Landlord shall be entitled to enter the Premises to perform an
     audit or survey of electrical use thereon from time to time. Tenant's
     consumption of electrical services shall not exceed either the rated
     capacities and/or design loads set forth in subsections (i) and (ii) above
     nor shall it generate heat in excess of that which Landlord's air
     conditioning system is designed to handle. In the event that Tenant elects
     to add equipment and/or lighting to the Premises that will cause Tenant's
     consumption of electrical services to exceed either the rated capacities
     and/or design loads set forth in subsections (i) and (ii) above or that
     will generate heat in excess of that which Landlord's air conditioning
     system is designed to handle, Tenant shall obtain Landlord's prior written
     approval of such equipment and/or lighting subject to the following:

               (1) Tenant shall pay for all costs of installation and
          maintenance of submeters, wiring, additional air conditioning systems
          and other items required by Landlord, in Landlord's

                                       15
<PAGE>   94
           discretion, to accommodate Tenant's excess design loads and
           capacities or heat production.

                (2) Tenant shall pay to Landlord, upon demand, the cost of the
           excess demand and consumption of electrical service at rates
           determined by Landlord (which rates shall be in accordance with any
           applicable laws) as well as all costs of operating additional air
           conditioning systems deemed necessary by Landlord on account of
           Tenant's excess consumption.

                (3) Landlord may, at its option, upon not less than thirty (30)
           days' prior written notice to Tenant, discontinue the availability of
           any or all utility service and in such event Tenant shall contract
           directly with such public utility for the supplying of such
           additional utility service to the Premises.

Landlord hereby approves the loads designed in the Space Plan and Construction
Specifications attached as Exhibit B-1 to the Work Agreement and confirms that
no additional costs will be incurred to provide such capacity.

      15. PARKING

      (a) Tenant shall have the right to use sixty-three (63) parking spaces
(i.e., three spaces for each 1,000 square feet of Net Rentable Area leased)
in the garage of the Complex throughout the Lease Term at no charge. All parking
spaces will be unreserved except for one, which will be a reserved space
reasonably close to the elevator core of the Building. However, until the Phase
II Commencement Date, Tenant shall have the right to use only forty (40) of said
sixty-three (63) parking spaces. Landlord may, in its sole and absolute
discretion, designate parking areas within the Complex for Tenant and Tenant's
agents and employees. In the event that Tenant, its agents and employees park in
locations other than those assigned to Tenant, Landlord reserves the right to
charge Tenant a fee of Twenty-Five and no/100 Dollars ($25.00) per day, which
fee is subject to increase from time to time at Landlord's sole option, for each
such occurrence in addition to towing such cars at Tenant's expense. Cars not
parked according to the rules and regulations promulgated by Landlord may be
towed at the owner's expense.

      (b) Use of the parking facilities serving the Complex is at the sole risk
of the users of such facilities, and Landlord assumes no liability for personal
injury, theft or property damage, or any other loss occurring during, as a
result of, or in connection with such use. Landlord shall have no liability
whatsoever to Tenant or any other person (including, without limitation,
Tenant's agents, employees, invitees, guests, clients or customers) for any
property damage to vehicles or their contents and/or personal injury which might
occur as a result of or in connection with the parking of vehicles in or about
the Complex. Tenant shall indemnify and hold Landlord harmless from and against
any and all costs, claims, causes of action, and expenses (including reasonable
attorneys' fees) which Landlord may incur in connection with

                                       16
<PAGE>   95
or arising out of use of the parking facilities by Tenant and/or Tenant's
agents, employees, invitees, guests, clients or customers.

     (c) In its use of the spaces, Tenant shall follow all of the rules of the
Complex applicable thereto, as the same may be reasonably amended from time to
time. Upon the occurrence of any breach of such rules, Landlord shall give
written notice to Tenant. If such default is not cured within fifteen (15) days
after Tenant's receipt of such notice, Landlord shall be entitled to terminate
Tenant's rights to lease spaces in the parking facilities of the Complex under
this Section, in which event Tenant's right to use any and all of the spaces
hereunder shall thereupon cease. In the event of substantial casualty damage to
the parking facilities, which in accordance with the terms of this Lease makes
it impossible or impractical for Landlord economically to comply with this
Section, the license granted under this Section shall terminate upon and as of
the date of such casualty. If the parking facilities (or a portion thereof) is
taken by governmental or quasi-governmental action or sale in lieu thereof and
such taking or sale makes it impractical or impossible for Landlord
economically to comply with this Section, this Section shall terminate as of
the date of such taking or sale.

     (d) To ensure that only those parties designated by Tenant are using the
parking facilities, Tenant shall provide Landlord with a complete list of the
names of all of Tenant's employees issued access cards, which list shall contain
the corresponding license plate numbers of those vehicles owned, leased or used
by each of said employees. Such list shall be updated by Tenant periodically, as
necessary, and shall contain a specific designation as to which vehicles of
which employees have been issued decals for parking spaces.

     (e) This Section shall not be deemed to create a bailment between the
parties hereto, it being expressly agreed and understood that the only
relationship created between Landlord and Tenant pursuant to this Section is
that of licensor and licensee, respectively.

     16. RULES AND REGULATIONS. Tenant will comply with the rules and
regulations of the Complex reasonably adopted by Landlord from time to time and
will cause all of its agents, employees, and invitees to do so. Any changes to
such rules and regulations will be sent by Landlord to Tenant in writing. The
current rules and regulations for the Complex are attached hereto as Exhibit D
and incorporated herein for all purposes. Nothing contained in this Lease shall
be construed as imposing upon Landlord any duty or obligation to enforce such
rules and regulations against any other tenant, and Landlord shall not be
liable to Tenant for the violation of such rules or regulations by any other
tenant or its employees, agents, or invitees. If there are any inconsistencies
between this Lease and the provisions of the rules and regulations, the
provisions of this Lease will prevail.

     17. COMPLIANCE WITH LAWS. Tenant shall, at its own cost and expense,
promptly observe and comply with all present and future laws, ordinances
(including, without limitation, the ADA, zoning ordinances, and land use
requirements), regulations, and orders of the United States of America, the
Commonwealth of Virginia, the County of Fairfax, and any other public or
quasipublic authority having jurisdiction over the Premises concerning the use,
occupancy and

                                       17
<PAGE>   96
condition of the Premises and all machinery, equipment and furnishings therein.
Tenant shall pay all costs, expenses, liabilities, losses, damages, fines,
penalties, claims and demands, including reasonable attorneys' fees, that may
in any manner arise out of or be imposed because of the failure of Tenant to
comply with the covenants of this Section. Landlord represents and warrants
that the tenant improvements to be constructed by Landlord pursuant to
Exhibit B attached hereto will comply with the ADA and all other applicable
laws, ordinances, regulations, and orders as of the date Landlord delivers
possession of the Phase I Space and The Phase II Space to Tenant. Landlord shall
comply with such laws, ordinances, regulations and orders concerning (i) the
use, occupancy and condition of the Common Areas and Exterior Common Areas of
the Complex, (ii) the condition and maintenance of the structure of the Complex
and (iii) the operation, maintenance, and repair of the mechanical, electrical,
and plumbing systems (including, without limitation, the HVAC and life safety
systems) serving the entire Complex. It is expressly understood that if any
present or future law, ordinance, regulation or order requires an occupancy
permit for the Premises, Tenant will obtain such permit at Tenant's own
expense; however, the nonresidential use permit(s) to be obtained in connection
with the improvements constructed by Landlord pursuant to the Work Agreement
attached hereto as Exhibit B shall be obtained by Landlord at Landlord's
expense.

     18. ENTRY BY LANDLORD. Upon reasonable oral notice to Tenant, Tenant shall
permit Landlord or its agents or representatives to enter into and upon any
part of the Premises at all reasonable hours (and in emergencies at all times)
to inspect the same, or to show the Premises to prospective purchasers,
mortgagees, tenants, or insurers, to clean or make repairs, alterations or
additions thereto, and Tenant shall not be entitled to any abatement or
reduction of rent by reason thereof. Tenant agrees to cooperate with Landlord
in event of emergencies, including, without limitation, evacuation at
Landlord's oral request in the event of any situation deemed by Landlord as an
emergency.

     19. ASSIGNMENT AND SUBLETTING.

     (a) Tenant shall not assign, transfer, mortgage or otherwise encumber this
Lease or its interest therein, or sublet, rent or permit anyone to occupy the
Premises, or any part thereof, without giving Landlord fifteen (15) business
days' prior written notice of Tenant's intention to assign or sublet the
Premises and obtaining the prior written consent of Landlord. Landlord shall
not withhold or delay its consent to any assignment of this Lease or a sublease
of the Premises if all of the following conditions have been satisfied: (i)
Tenant shall have demonstrated, to Landlord's satisfaction, that the use of the
Premises shall comply with the terms of this Lease and that, in the case of an
assignment, the credit-worthiness of the assignee is comparable to that of
other tenants in the Complex for similar leases in space of similar size or
quality; (ii) the form and content of any assignment or sublease documents
shall have been reasonably approved by Landlord and its counsel; (iii) Tenant
shall have reimbursed Landlord for any reasonable attorneys' fees and expenses
incurred by Landlord in connection with such assignment or sublease; and (iv)
the assignee or subtenant is not a tenant in the Complex unless Landlord
confirms that there is no prime office space available. Notwithstanding
anything to the contrary in this Lease, Landlord may condition its consent to a
proposed assignment upon

                                       18
<PAGE>   97
Tenant's execution and delivery of a guaranty in a form acceptable to Landlord
and its counsel of the monetary performance by the proposed assignee of its
financial obligations under this Lease. If Landlord denies consent to an
assignment solely because of the credit-worthiness of the assignee and there has
been no deterioration in the credit-worthiness of Tenant since the date of this
Lease, Tenant may satisfy such condition by posting a security deposit and/or
providing a lease guaranty acceptable to Landlord. No assignment or transfer of
this Lease or the right of occupancy hereunder may be effectuated by operation
of law or otherwise without the prior written consent of Landlord. The consent
by Landlord to any assignment or subletting shall not be construed as a waiver
or release of Tenant from liability for the performance of all covenants and
obligations to be performed by Tenant under this Lease, nor shall the collection
or acceptance of rent from any assignee, subtenant or occupant constitute a
waiver or release of Tenant from any of its liabilities or obligations under
this Lease. Landlord's consent to any assignment or subletting shall not be
construed as relieving Tenant from the obligation of obtaining Landlord's prior
written consent to any subsequent assignment or subletting. If an Event of
Default has occurred and is continuing, Tenant hereby assigns to Landlord the
rent due from any subtenant of Tenant and hereby authorizes each such subtenant
to pay said rent directly to Landlord. Tenant shall pay to Landlord a Five
Hundred Dollar ($500.00) processing fee as well as expenses (including
reasonable attorneys' fees) incurred by Landlord in connection with Tenant's
request for Landlord to give its consent to any assignment, subletting,
occupancy or mortgage, whether or not Landlord consents thereto.

     (b)  If Tenant is a partnership, a withdrawal or change, whether voluntary,
involuntary or by operation of law, of partners owning a controlling or majority
interest in Tenant shall be deemed a voluntary assignment of this Lease and
subject to the provisions of subsection (a) above. If Tenant is a corporation,
any dissolution, merger, consolidation or other reorganization of Tenant, or the
sale or transfer (whether by way of one or more sales or transfers) of a
controlling or majority interest of the capital stock of Tenant shall be deemed
a voluntary assignment of this Lease and subject to the provisions of this
Section. However, the preceding sentence shall not apply to corporations the
stock of which is traded through a national or regional exchange or
over-the-counter.

     (c)  If Tenant desires to assign or sublet more than fifty percent (50%) of
the rentable area of the Premises (i.e., 50% in the aggregate including any
prior or simultaneously assigned or subleased space), Landlord shall have the
option to terminate this Lease with regard to that portion of the Premises that
Tenant desires to assign or sublet and, in addition, Landlord shall have the
option to require any existing assignees or sublessees of Tenant to attorn to
Landlord. Landlord may exercise the option by giving Tenant written notice
within thirty (30) days after Landlord has received Tenant's written notice of
intention to assign or sublet pursuant to this Section. The effective date of
termination shall be mutually agreed upon by Landlord and Tenant, and, if they
cannot agree upon a termination date, the termination date will be ninety (90)
days from the date Landlord received the notice that Tenant desires to assign or
sublet more than fifty percent (50%) of the rentable area of the Premises. Upon
termination, all of the rights and obligations of Landlord and Tenant under the
terms of this Lease shall be terminated with regard only to that portion of the
rentable area of the Premises which Tenant notified Landlord

                                       19
<PAGE>   98
that Tenant desires to assign or sublet, except the obligation of Tenant to pay
rent and all other charges that accrue to the date of termination. The options
of Landlord under this Section shall apply to each assignment or sublease by
Tenant and a waiver by Landlord as to one assignment or sublease shall not
affect any subsequent assignment or sublease.

     (d)  If Tenant desires to assign or sublet the whole or a part of the
Premises, Landlord may condition its consent to the subletting or assignment on
the requirement that fifty percent (50%) of the net profit derived by Tenant
from the assignment or subletting shall be paid by Tenant to Landlord as
additional rent. Net profit shall be deemed to mean the net proceeds received by
Tenant from any subletting or assignment less brokerage and other expenses
incurred in making the assignment or sublease amortized, however, over the term
of the assignment or sublease, said net profit to be paid monthly to Landlord by
Tenant at the times that the subrent or assignment charge is paid by the
subtenant or assignee to Tenant and as and when the same is received by Tenant.
Tenant expressly waives any right that it may have to retain such excess
pursuant to the provisions of Section 365(f) of the Bankruptcy Code.

     20.  INSURANCE.

     (a)  Throughout the Lease Term, Tenant shall obtain and maintain commercial
general liability insurance on an occurrence basis protecting against any
liability occasioned by any occurrence on or about the Premises and containing
contractual liability coverage. Such insurance shall be initially in minimum
amounts of Two Million Dollars ($2,000,000) per occurrence and shall be for a
minimum term of one (1) year.

     (b)  Throughout the Lease Term, Tenant shall also obtain and maintain
throughout the Lease Term insurance coverage for all risks and perils as
customarily provided by insurance companies to insure against damage to or loss
of the contents of the Premises, including, without limitation, alterations,
decorations, or improvements to the Premises previously made by Tenant or any
trade fixtures, furnishings, equipment or personal property belonging to Tenant.
Such policy shall be for the full insurable value of such property and shall not
be subject to a deductible in excess of $10,000.

     (c)  Each of said policies of insurance shall name Landlord and Landlord's
managing agent as an additional insured, and if requested by the holder of any
mortgage or deed of trust against the Complex, the public liability policy
referred to above shall also name such holder as an additional insured. Each
policy shall contain an endorsement which provides that no cancellation or
reduction of coverage may be made without first giving Landlord and, if named as
an additional insured, the holder of any mortgage or deed of trust on the
Complex, at least thirty (30) days' prior written notice of such proposed
action. All of Tenant's insurance required under this Lease shall be written as
primary policy coverage and not contributing with or in excess of any coverage
which Landlord may carry. All insurance policies required from Tenant under this
Lease shall be issued by insurance companies licensed to do business in the
jurisdiction wherein the Complex is located with a financial rating of at least
an A:XII as rated in the most recent edition of Best Insurance Reports and in
business for the past five (5) years.

                                       20
<PAGE>   99
On or before the Phase I Commencement Date, and thereafter not less than fifteen
(15) days prior to the expiration dates of said policy or policies, Tenant shall
provide copies of policies or certificates of insurance (ACORD 27) evidencing
the coverages required by this Section. The aforesaid insurance limits may be
reasonably increased from time to time by Landlord.

     (d)  Throughout the Lease Term, Landlord shall obtain and maintain (i)
insurance against all risks of physical loss or damage to the Complex and (ii)
comprehensive liability insurance on an "occurrence basis" against claims or
damages of death, bodily injury, or property damage occurring in or about the
Complex. All insurance maintained by Landlord shall be in amounts deemed
reasonable and prudent for a first-class office building in the Tyson's Corner
business district.

     (e)  Anything in this Lease to the contrary notwithstanding, Landlord and
Tenant each hereby waives any and all rights of recovery, claim, action, or
cause of action, against the other, its agents, officers, or employees, for any
loss or damage that may occur to the Premises, or any improvements thereto, or
the Complex of which the Premises are a part, or any improvements thereto, or
any personal property of such party therein, by reason of fire, the elements, or
any other cause(s) which may be insured against under the terms of insurance
policies properly endorsed, regardless of cause or origin, including negligence
of the other party hereto, its agents, officers, or employees, and without
regard to whether any such policies are maintained, and without regard to the
amount of any deductibles. The provisions of this Section are conditioned upon
the ability of Landlord and Tenant to each obtain endorsements, at no additional
cost, to their property insurance with respect to the Complex consistent with
this Section. Each property insurance policy shall also provide that the policy
shall not be invalidated in the event that the insured waives, in writing prior
to a loss, any or all rights of recovery against any party for losses covered by
such policy. If Tenant is unable to obtain the provisions set forth herein from
its property insurance company, Tenant shall name Landlord as an insured on
Tenant's property insurance policy.

     21.  PROPERTY TAXES. Landlord agrees to pay all Real Estate Taxes, and
increases in Real Estate Taxes shall be passed through to Tenant as Operating
Expenses to be paid in accordance with the terms of this Lease. Tenant shall be
liable for all taxes levied against personal property and trade fixtures placed
by Tenant in the Premises. If any taxes for which Tenant is liable under this
Section are levied against Landlord or Landlord's property and if Landlord
elects to pay the same or if the assessed value of the Complex is increased by
inclusion of personal property and trade fixtures placed by Tenant in the
Premises and Landlord elects to pay the taxes based on such increase, Tenant
shall pay to Landlord upon demand as additional rent that part of such taxes for
which Tenant is primarily liable hereunder.

     22. MUTUAL INDEMNIFICATION. Subject to the waiver of claims set forth in
Section 20(e) of this Lease, Tenant shall indemnify and hold Landlord and
Landlord's agents and its and their officers, directors, and employees, harmless
from and against all costs, damages, claims, liabilities and expenses (including
reasonable attorneys' fees) suffered by or claimed against Landlord and
Landlord's agents and its and their officers, directors, and employees, directly
or

                                       21
<PAGE>   100
indirectly, based on, arising out of or resulting from (i) Tenant's use and
occupancy of the Premises or the business conducted by Tenant therein, (ii) any
negligent act or omission by Tenant or its employees, agents or invitees, or
(iii) any breach or default by Tenant in the performance or observance of its
covenants or obligations under this Lease. Subject to the waiver of claims set
forth in Section 20(e) of this Lease, Landlord shall indemnify and hold Tenant
and Tenant's agents and its and their officers, directors and employees harmless
from and against all costs, damages, claims, liabilities and expenses (including
reasonable attorneys' fees) suffered by or claimed against Tenant and Tenant's
agents and its and their officers, directors, members, and employees to the
extent directly or indirectly, based on, arising out of or resulting from (i)
any negligent act or omission by Landlord or its employees, agents or invitees,
in the operation of the Complex; (ii) latent defects in the Complex; or (iii)
any breach or default by Landlord in the performance or observance of its
covenants or obligations under this Lease.

     23. CASUALTY DAMAGE. If the Premises or any part thereof shall be damaged
by fire or other casualty, Tenant shall give prompt written notice thereof to
Landlord. In case the Complex shall be so damaged that substantial alteration or
reconstruction of the Complex shall, in Landlord's reasonable opinion, be
required (whether or not the Premises shall have been damaged by such casualty)
or in the event any mortgagee of Landlord's should require that the insurance
proceeds payable as a result of a casualty be applied to the payment of the
mortgage debt and not to reconstruction of the Complex, or in the event of any
material uninsured loss to the Complex for which Landlord is not required to
insure under the terms of this Lease, Landlord may, at its option, terminate
this Lease by notifying Tenant in writing of such termination within ninety (90)
days after the date of such damage. In furtherance of the foregoing, but not in
limitation thereof, if the repairs and restoration of the Premises cannot be
completed within one hundred fifty (150) days after the occurrence of such
damage (taking into account the time needed for removal of debris, preparation
of plans and issuance of all required governmental permits), Landlord and Tenant
shall have the right, at the option of either, to terminate this Lease as
described in the following sentences. Within forty-five (45) days after the
occurrence of such damage, Landlord shall provide reasonable assurances to
Tenant that such repairs and restoration can be substantially completed within
one hundred fifty (150) days of the occurrence of the damage and that Landlord
intends to perform such repairs and restoration. If Landlord so informs Tenant
that such repairs and restoration can be completed within such time, this Lease
shall continue and Landlord shall use its reasonable best efforts to complete
said repairs and restoration within said 150-day period. If Landlord fails to
provide such assurances, then Tenant shall have the right to notify Landlord
within fifteen (15) days that it is terminating this Lease. If the restoration
of the Premises is not substantially completed within said 150-day period due to
no fault of Tenant, Tenant shall have the right to terminate this Lease by
giving notice to Landlord no later than the second business day following the
end of said 150-day period. If this Lease is terminated pursuant to the
preceding sentences, all rent payable hereunder shall be apportioned and paid to
the date of the occurrence of such damage. If this Lease is not terminated,
Landlord shall, following settlement of Landlord's insurance claims, promptly
commence and proceed with reasonable diligence to restore the Premises and the
Complex to substantially the same condition in which they were immediately prior
to the

                                       22
<PAGE>   101
happening of the casualty, except that Landlord's obligation to restore shall
not exceed the scope of the work required to be done at Landlord's expense in
originally constructing the Complex and the scope of the work in the Premises as
described in the Work Agreement attached hereto as Exhibit B, nor shall Landlord
be required to spend an amount in excess of the deductible amount in Landlord's
policy and the insurance proceeds actually received by Landlord as a result of
the casualty. At such time as Landlord has completed its reconstruction
obligations as above set forth, Tenant shall, at Tenant's expense, complete the
restoration of the Premises. Landlord shall not be liable to Tenant for the
repair or replacement of any installation made by Tenant. Repairs or
replacements of installations made by Tenant or of Tenant's furniture, fixtures,
equipment and contents shall be made by Tenant at its sole cost. Landlord shall
not be liable for any inconvenience or annoyance to Tenant or injury to the
business of Tenant resulting in any way from such damage or the repair thereof,
except that, subject to the provisions of the next sentence, Landlord shall
allow Tenant a pro rata diminution of rent during the time and based on the
portion of the Premises that are damaged and unfit for occupancy. If the
Premises or any other portion of the Complex is damaged by fire or other
casualty resulting from the negligence of Tenant or any of Tenant's agents or
employees, the rent hereunder shall not be diminished during the repair of such
damage.

     24. CONDEMNATION. If the whole or substantially the whole of the Complex or
the Premises should be taken for any public or quasi-public use, by right of
eminent domain or otherwise or should be sold in lieu of condemnation, then this
Lease shall terminate as of the date when physical possession of the Complex or
the Premises is taken by the condemning authority, and rent shall be prorated as
of such date. If less than the whole or substantially the whole of the Complex
or the Premises is thus taken or sold, Landlord (whether or not the Premises are
affected thereby) may terminate this Lease by giving written notice thereof to
Tenant, in which event this Lease shall terminate as of the date when physical
possession of such portion of the Complex or Premises is taken by the condemning
authority. If as a result of the condemnation, a material portion of the
Premises are taken and are rendered unsuitable for Tenant's business operations,
Tenant may terminate this Lease by giving written notice thereof to Landlord, in
which event this Lease shall terminate as of the date when physical possession
of such portion of the Premises is taken by the condemning authority. If this
Lease is not so terminated upon any such taking or sale, the rent payable
hereunder shall be diminished by a pro rata amount based on the portion of the
Premises taken or sold, and Landlord shall, within a reasonable period of time
following receipt of condemnation proceeds, to the extent Landlord deems
feasible, promptly and diligently restore the Complex and the Premises to
substantially their former condition, but such work shall not exceed the scope
of work done by Landlord in originally constructing the Complex and the scope of
the work in the Premises as described in the Work Agreement, nor shall Landlord
in any event be required to spend for such work an amount in excess of the
amount received by Landlord as compensation for such damage. All amounts awarded
upon a taking of any part or all of the Complex or the Premises shall belong to
Landlord, and Tenant shall not be entitled to and expressly waives all claim to
any such compensation. However, if a portion of the award is specifically
allocated to Tenant's property and moving and relocation expenses, Tenant shall
be entitled to such portion of the award.

                                       23
<PAGE>   102
     25.  DAMAGES FROM CERTAIN CAUSES. Landlord shall not be liable to Tenant
for any loss or damage to any property or person occasioned by theft, fire, act
of God, public enemy, injunction, riot, strike, insurrection, war, court order,
requisition, or order of governmental body or authority or by any other cause
beyond the reasonable control of Landlord. Nor shall Landlord be liable for any
damage or inconvenience which may arise through repair or alteration of any part
of the Complex or Premises except for damage caused by the gross negligence or
intentional misconduct of Landlord or its agents. Except as set forth in
Sections captioned "Casualty Damage" and "Condemnation" and Section 8(b) above,
the causes of loss or damage set forth in this Section shall not affect the
continuation or validity of this Lease or Tenant's obligation to pay rent
hereunder.

     26.  EVENT OF DEFAULT/REMEDIES.

     (a)  The following events shall be deemed to be Events of Default by
Tenant under this Lease:

          i)   Tenant shall fail to comply with any provision of this Lease (or
     any other agreement between Landlord and Tenant) requiring the payment of
     money and such failure shall continue for a period of five (5) days
     following written notice thereof from Landlord to Tenant of such default;
     provided, however, that in no event shall Tenant be entitled to more than
     two (2) such notices during any twelve (12) month period;

          ii)  Tenant shall violate or fail to perform any other term,
     condition, covenant or agreement to be performed or observed by Tenant
     under this Lease, all of which shall be deemed material and such failure
     shall continue for more than thirty (30) days following notice thereof from
     Landlord to Tenant, said thirty-day period to be increased by an additional
     thirty (30) days if Tenant shall have commenced and diligently proceeded to
     cure such default within said initial thirty-day period;

          iii) the leasehold hereunder demised shall be taken on execution or
     other process of law in any action against Tenant or Tenant shall become
     insolvent or unable to pay its debts as they become due, or Tenant notifies
     Landlord that it anticipates either condition;

          iv)  Tenant shall fail to move into and take possession of the
     Premises when the Premises are ready for occupancy in accordance with the
     terms hereof, or Tenant shall at any time vacate or abandon the Premises
     without Landlord's prior written approval; however, Landlord will not
     accelerate the rent due under this Lease if Tenant vacates the Premises and
     does not find a suitable assignee or subtenant provided Tenant continues to
     pay rent and is not otherwise in default under this Lease and gives thirty
     (30) days' advance written notice to Landlord of Tenant's intention to
     vacate the space;

                                       24
<PAGE>   103
          v)   Tenant, any guarantor of this Lease ("Guarantor"), or any parent
     or holding company of Tenant (if Tenant is a corporation) files a petition
     under any section or chapter of the Title 11 of the United States Code, as
     amended, or under any similar existing or subsequently enacted law or
     statute of the United States or any State thereof, or a petition shall be
     filed against Tenant or any of said entities or persons under any such
     statute and such petition is not dismissed or vacated within ninety (90)
     days from the filing thereof; or

          vi)  a receiver or trustee shall be appointed for Tenant's leasehold
     interest in the Premises or for all or a substantial part of the assets of
     Tenant or any Guarantor and such order of appointment is not dismissed or
     vacated within ninety (90) days from the entry of such order.

     (b)  If an Event of Default shall have occurred, Landlord shall have the
right, at its sole option, to terminate this Lease. With or without terminating
this Lease, Landlord may re-enter and take possession of the Premises and the
provisions of this Section shall operate as a notice to quit; and any other
notice to quit or notice of Landlord's intention to re-enter the Premises being
hereby expressly waived. If necessary, Landlord may proceed to recover
possession of the Premises under and by virtue of the laws of the Commonwealth
of Virginia, or by such other proceedings, including re-entry and possession,
as may be applicable. If Landlord elects to terminate this Lease, everything
contained in this Lease on the part of Landlord to be done and performed shall
cease without prejudice, however, to the right of Landlord to recover from
Tenant all rent and other sums accrued up to the time of termination or
recovery of possession by Landlord, whichever is later. Whether or not this
Lease is terminated by reason of Tenant's default, the Premises may be relet by
Landlord for such rent and upon such terms as Landlord deems reasonable under
the circumstances and, if the full rental provided herein plus the costs,
expenses and damages described below shall not be realized by Landlord, Tenant
shall be liable for all damages sustained by Landlord, including, without
limitation, deficiency in Base Rental and additional rent, reasonable
attorneys' fees, brokerage fees, and the expenses of placing the Premises in
first-class rentable condition. Any damages or loss of rent sustained by
Landlord may be recovered by Landlord, at Landlord's option, at the time of the
reletting, or in separate actions, from time to time, as said damage shall have
been made more easily ascertainable by successive relettings, or, at Landlord's
option, may be deferred until the expiration of the Lease Term, in which event
Tenant hereby agrees that the cause of action shall not be deemed to have
accrued until the date of expiration of the Lease Term. Landlord, however,
shall use reasonable efforts to mitigate its damages hereunder so long as
Tenant cooperates in allowing Landlord to show the Premises to prospective
tenants. The provisions contained in this Section shall be in addition to, and
shall not prevent the enforcement of, any claim Landlord may have against
Tenant for anticipatory breach of this Lease.

     (c)  All rights and remedies of Landlord set forth herein are in addition
to all other rights and remedies available to Landlord at law or in equity. All
rights and remedies available to Landlord hereunder, at law or in equity, are
expressly declared to be cumulative. The

                                       25
<PAGE>   104
exercise by Landlord of any such right or remedy shall not prevent the
concurrent or subsequent exercise of any other right or remedy. No delay in
the enforcement or exercise of any such right or remedy shall constitute a
waiver of any default by Tenant hereunder or of any of Landlord's rights or
remedies in connection therewith. Landlord shall not be deemed to have waived
any default by Tenant hereunder unless such waiver is set forth in a written
instrument signed by Landlord. If Landlord waives in writing any default by
Tenant, such waiver shall not be construed as a waiver of any covenant,
condition or agreement set forth in this Lease except as to the specific
circumstances described in such written waiver.

     (d)  Interest shall accrue on sums due hereunder from Tenant but not paid,
at the lesser of 12% per annum or the highest rate permitted by applicable law.
The provisions of the Section captioned "Holding Over" shall apply with respect
to the period from and after written notice to Tenant of the demand for payment.

     (e)  In no event shall Tenant have the right to terminate or rescind, or
to withhold, offset or deduct any amount otherwise payable under, this Lease as
a result of Landlord's default of any covenant or agreement contained in this
Lease or as a result of the breach of any promise or inducement hereof, whether
in this Lease or elsewhere. Tenant hereby waives such remedies of termination,
rescission, withholding, offset and deduction, and hereby agrees that Tenant
remedies for default hereunder and for breach of any promise or inducement
shall be limited to a suit for damages and/or injunction. In addition, Tenant
hereby covenants that, prior to the exercise of any such remedies, it will give
the mortgagees on the Complex notice and a reasonable time to cure any default
by Landlord.

     (f)  In addition to all other remedies available to Landlord hereunder,
upon the occurrence of an Event of Default, Landlord may make demand for and
obtain an immediate judgment for all monies due and owing as rent or additional
rent under the terms and conditions of this Lease from the date of default
through the expiration date of the tenancy as set forth in this Lease and in
addition thereto, Landlord shall be entitled to recover immediately all
unamortized costs paid by Landlord as a result of the tenancy, including,
without limitation, tenant improvements, leasing commissions, rent abatements,
and attorneys' fees incurred in negotiating this Lease.

     27.  BANKRUPTCY OF TENANT.

     (a)  If a petition is filed by, or an order for relief is entered against,
Tenant under Chapter 7 of the Bankruptcy Code and the trustee of Tenant elects
to assume this Lease for the purpose of assigning it, the election or
assignment, or both, may be made only if all of the terms and conditions of
subsections (b) and (c) of this Section are satisfied. If the trustee fails to
elect to assume this Lease for the purpose of assigning it within sixty (60)
days after trustee's appointment, this Lease will be deemed to have been
rejected. Landlord shall then immediately be entitled to possession of the
Premises without further obligation to Tenant or the trustee, and this Lease
will be canceled. Landlord's right to be compensated for damages in this
bankruptcy proceeding, however, shall survive.

                                       26
<PAGE>   105
     (b)  If Tenant files a petition for reorganization under chapters 11 or 13
of the Bankruptcy Code or a proceeding that is filed by or against Tenant
under any other chapter of the Bankruptcy Code is converted to a chapter 11 or
13 proceeding and Tenant's trustee or Tenant as a debtor-in-possession fails to
assume this Lease within sixty (60) days from the date of the filing of the
petition or the conversion, the trustee or the debtor-in-possession will be
deemed to have rejected this Lease. To be effective, an election to assume this
Lease must be in writing and addressed to Landlord and, in Landlord's business
judgment, all of the following conditions, which Landlord and Tenant
acknowledge to be commercially reasonable, must have been satisfied:

          i)  The trustee or the debtor-in-possession has cured or has provided
     to Landlord adequate assurance, as defined in this section, that:

              (A)  The trustee will cure all monetary defaults under this Lease
          within ten (10) days from the date of the assumption; and

              (B)  The trustee will cure all nonmonetary defaults under this
          Lease within thirty (30) days from the date of assumption.

          ii)  The trustee or the debtor-in-possession has compensated Landlord,
       or has provided to Landlord adequate assurance, as defined in this
       Section, that within ten (10) days from the date of the assumption
       Landlord will be compensated for any pecuniary loss Landlord incurred
       arising from the default of Tenant, the trustee, or the
       debtor-in-possession as recited in Landlord's written statement of
       pecuniary loss sent to the trustee or the debtor-in-possession.

         iii)  The trustee or the debtor-in-possession has provided Landlord
       with adequate assurance of the future performance of each of Tenant's
       obligations under this Lease; provided, however, that the trustee or
       debtor-in-possession will also deposit with Landlord, as security for the
       timely payment of rent, an amount equal to three (3) months' Base Rent
       and additional rent for pass-throughs of Operating Expenses and other
       monetary charges accruing under this Lease.

           iv)  Landlord has determined that the assumption of this Lease will
       not breach any provision in any other lease, mortgage, financing
       agreement, or other agreement by which Landlord is bound relating to the
       Complex.

            v)  For purposes of this section, "adequate assurance" means that:

              (A)  Landlord will determine that the trustee or the
            debtor-in-possession has, and will continue to have, sufficient
            unencumbered assets after the payment of all secured obligations
            and administrative expenses to assure Landlord that the trustee or

                                       27

<PAGE>   106
             the debtor-in-possession will have sufficient funds to fulfill
             Tenant's obligations under this Lease; and

                   (B)  An order will have been entered segregating sufficient
             cash payable to Landlord and/or a valid and perfected first lien
             and security interest will have been granted in property of Tenant,
             trustee, or debtor-in-possession that is acceptable for value and
             kind to Landlord, to secure to Landlord the obligation of the
             trustee or debtor-in-possession to immediately cure any monetary or
             nonmonetary defaults under this Lease.

       (c)   In the event that this Lease is assumed by a trustee appointed for
Tenant or by Tenant as debtor-in-possession under the provisions of subsection
(b) above and, thereafter, Tenant is either adjudicated a bankrupt or files a
subsequent petition for arrangement under chapter 11 of the Bankruptcy Code,
then Landlord may terminate, at its option, this Lease and all of Tenant's
rights under it, by giving written notice of Landlord's election to terminate.

       (d)   If the trustee or the debtor-in-possession has assumed this Lease,
under the terms of subsections (a) or (b) above, to assign or to elect to
assign Tenant's interest under this Lease or the estate created by that
interest to any other person, that interest or estate may be assigned only if
Landlord acknowledges in writing that the intended assignee has provided
adequate assurance, as defined in this subsection (d), of future performance of
all of the terms, covenants, and conditions of this Lease to be performed by
Tenant. For the purposes of this subsection (d), adequate assurance of future
performance means that Landlord has ascertained that each of the following
conditions has been satisfied:

              i)  The assignee has submitted a current financial statement,
        audited by a certified public accountant, that shows a net worth and
        working capital in amounts determined by Landlord to be sufficient to
        assure the future performance by the assignee of Tenant's obligation
        under this Lease.

             ii)  If requested by Landlord, the assignee will obtain
        guarantees, in form and substance satisfactory to Landlord, from one or
        more persons who satisfy Landlord's standards of credit-worthiness.

            iii)  Landlord has obtained all consents or waivers from any third
        party required under any lease, mortgage, financing arrangement, or
        other agreement by which Landlord is bound, to enable Landlord to
        permit the assignment.

        (e)  When, pursuant to the Bankruptcy Code, the trustee or the
debtor-in-possession is obligated to pay reasonable use and occupancy charges
for the use of all or part of the Premises, the charges will not be less than
the Base Rent as defined in this Lease and other monetary obligations of Tenant
for the payment of additional rent.

                                       28
<PAGE>   107
     (f)  Neither Tenant's interest in this Lease nor any estate of Tenant
created in this Lease will pass to any trustee, receiver, assignee for the
benefit of creditors, or any other person or entity, or otherwise by operation
of law under the laws of any state having jurisdiction of the person or
property of Tenant, unless Landlord consents in writing to this transfer.
Landlord's acceptance of rent or any other payments from any trustee, receiver,
assignee, person, or other entity will not be deemed to have waived, or waive,
the need to obtain Landlord's consent or Landlord's right to terminate this
Lease for any transfer of Tenant's interest under this Lease without that
consent.

     28.  ENVIRONMENTAL LIABILITY.

     (a)  The term "Hazardous Materials" for purposes hereof shall mean (i)
"hazardous wastes," as defined by the Resource Conservation and Recovery Act of
1976, as amended from time to time, (ii) "hazardous substances," as defined by
the Comprehensive Environmental Response, Compensation and Liability Act of
1980, as amended from time to time, (iii) "toxic substances," as defined by the
Toxic Substances Control Act, as amended from time to time, (iv) "hazardous
materials," as defined by the Hazardous Materials Transportation Act, as
amended from time to time, (v) oil or other petroleum products, (f) any
substances whose presence could be detrimental to the Complex or hazardous to
health or the environment, and (g) any chemical, substance, materials or waste
or component thereof which is now or hereafter listed, defined or regulated as
a hazardous or toxic chemical, substance, materials or waste or component
thereof by any federal, state or local governing or regulatory body having
jurisdiction, or which would trigger any employee or community "right-to-know"
requirements adopted by any such body, or for which any such body has adopted
any requirements for the preparation or distribution of a materials safety data
sheet ("MSDS").

     (b)  Tenant shall not transport, use, store, maintain, generate,
manufacture, handle, dispose, release or discharge any Hazardous Materials.
However, the foregoing provisions shall not prohibit the use, storage or
handling within the Premises of Hazardous Materials customarily used in the
operation of standard office equipment used by Tenant; provided, however, (i)
such Hazardous Materials shall be used and maintained only in such quantities
as are reasonably necessary for such equipment use strictly in accordance with
applicable law, highest prevailing standards, and the manufacturers'
instructions therefor, (ii) such Hazardous Materials shall not be disposed of,
released or discharged in the Complex, and shall be transported to and from the
Premises in compliance with all applicable laws, and as Landlord shall
reasonably require, (iii) if any applicable law or Landlord's trash removal
contractor requires that any such Hazardous Materials be disposed of separately
from ordinary trash, Tenant shall make arrangements at Tenant's expense for
such disposal directly with a qualified and licensed disposal company at a
lawful disposal site (subject to scheduling and approval by Landlord), and (d)
any remaining such Hazardous Materials shall be completely, properly and
lawfully removed from the Complex upon expiration or earlier termination of
this Lease.

     (c)  Tenant shall promptly notify Landlord of: (i) any enforcement,
cleanup or other regulatory action taken or threatened by any governmental or
regulatory authority with respect

                                       29
<PAGE>   108
to the presence of any Hazardous Materials on the Premises or the migration
thereof from or to other property, (ii) any demands or claims made or
threatened by any party relating to any loss or injury resulting from any
Hazardous Materials on the Premises, (iii) any release, discharge or
nonroutine, improper or unlawful disposal or transportation of any Hazardous
Materials on or from the Premises or in violation of this Section, and (iv) any
matters where Tenant is required by law to give a notice to any governmental or
regulatory authority respecting any Hazardous Materials on the Premises.
Landlord shall have the right (but not the obligation) to join and participate,
as a party, in any legal proceedings or actions affecting the Premises
initiated in connection with any environmental, health or safety law. At such
times as Landlord may reasonably request, Tenant shall provide Landlord with a
written list, certified to be true and complete, identifying any Hazardous
Materials then used, stored, or maintained upon the Premises, the use and
approximate quantity of each such material, a copy of any MSDS issued by the
manufacturer therefor, and such other information as Landlord may reasonably
require or as may be required by law.

     (d)  If any Hazardous Materials are released, discharged or disposed of by
Tenant or any other occupant of the Premises, or their employees, agents,
invitees or contractors, on or about the Complex in violation of the foregoing
provisions. Tenant shall immediately, properly and in compliance with
applicable laws clean up, remediate and remove the Hazardous Materials from the
Complex and any other affected property and clean or replace any affected
personal property (whether or not owned by Landlord), at Tenant's expense
(without limiting Landlord's other remedies therefor). Tenant shall indemnify
and hold Landlord, Landlord's directors, officers, employees and agents
harmless from and against any and all claims, demands, liabilities, losses,
damages, penalties and judgments directly or indirectly arising out of or
attributable to a violation of the provisions of this Section by Tenant,
Tenant's occupants, employees, contractors or agents. Any clean up, remediation
and removal work shall be subject to Landlord's prior written approval (except
in emergencies), and shall include, without limitation, any testing,
investigation, and the preparation and implementation of any remedial action
plan required by any governmental body having jurisdiction or reasonably
required by Landlord. If Landlord or any lender or governmental body arranges
for any tests or studies showing that this Section has been violated, Tenant
shall pay for the costs of such tests.

     (e)  Landlord represents and warrants to Tenant that to the best of the
knowledge of Renee T. Bergeron, Landlord's asset manager, in reliance solely
upon the Phase I Environmental Site Assessment dated January 11, 1995, prepared
by ATEC Associates, Inc., and without any other investigation by Landlord or
inquiry of the tenants in the Complex, (A) the Complex does not contain, and
there is not located on or about the Complex, any Hazardous Materials in amounts
in violation of any environmental laws or ordinances; (B) no part of the Complex
is currently used for the use, storage, treatment, production, manufacture,
generation, transportation, release or disposal of Hazardous Materials in
amounts in violation of any environmental laws or ordinances.

     (f)  The provisions of this Section shall survive the expiration or
earlier termination of this Lease.

                                       30

<PAGE>   109
     29.  QUIET ENJOYMENT.  Tenant shall, and may peacefully have, hold, and
enjoy the Premises, subject to the other terms hereof, provided that Tenant
pays the rent and other sums herein recited to be paid by Tenant and performs
all of Tenant's covenants and agreements herein contained. This covenant and
any and all other covenants of Landlord shall be binding upon Landlord and its
successors only with respect to breaches occurring during its or their
respective periods of ownership of the Landlord's interest hereunder.

     30.  HOLDING OVER.  In the event that Tenant shall not immediately
surrender the Premises on the date of the expiration of the Lease Term, Tenant
shall become a tenant by the month at one and one-half times the Base Rent and
all additional rent in effect during the last month of the Lease Term. Said
monthly tenancy shall commence on the first day following the expiration of the
Lease Term. As a monthly tenant, Tenant shall be subject to all the terms,
conditions, covenants and agreements of this Lease, except as to the amount of
the Base Rent, which shall be in the amount specified in this Section. Tenant
shall give to Landlord at least thirty (30) days' written notice of any
intention to quit the Premises, and Tenant shall be entitled to thirty (30)
days' written notice to quit the Premises, unless Tenant is in default
hereunder, in which event Tenant shall not be entitled to any notice to quit,
the usual thirty (30) days' notice to quit being hereby expressly waived.
Notwithstanding the foregoing provisions of this Section, in the event that
Tenant shall hold over after the expiration of the Lease Term, and if Landlord
shall desire to regain possession of the Premises promptly at the expiration of
the Lease Term, then at any time prior to Landlord's acceptance of rent from
Tenant as a monthly tenant hereunder, Landlord, at its option, may forthwith
re-enter and take possession of the Premises without process, or by any legal
process in force in the Commonwealth of Virginia. To the extent permitted by
law, Landlord may accept rent in the holdover amount and concurrently commence
legal proceedings to regain possession of the Premises.

     31.  SUBORDINATION AND ATTORNMENT.

     (a)  Provided Landlord obtains for the benefit of Tenant from Landlord's
mortgagee or ground lessor such mortgagee's or ground lessor's standard
nondisturbance agreement reasonably acceptable to Tenant, this Lease is and
shall remain subject and subordinate to the lien of any and all current and
future first mortgages and/or any ground leases (which term "mortgages" shall
include both construction and permanent financing and shall include deeds of
trust and similar security instruments) which may now encumber the Complex or
the land on which the Complex is located, and to all and any renewals,
extensions, modifications, consolidations, recastings or refinancings thereof.
At any time after the execution of this Lease, the holder of any mortgage to
which this Lease is subordinate shall have the right to declare this Lease to
be superior to the lien of such mortgage, and Tenant agrees to execute all
documents required by such holder in confirmation thereof.

     (b)  In the event that Tenant should fail to execute any instrument of
nondisturbance and subordination herein required to be executed by Tenant
within fifteen (15) days of Landlord's demand, Tenant hereby irrevocably
constitutes Landlord as its attorney-in-fact to

                                       31

<PAGE>   110
execute such instrument in Tenant's name, place and stead, it being agreed that
such power is one coupled with an interest.

     (c)  In the event any proceedings are brought for the foreclosure of any
mortgage encumbering the Complex or the termination of any ground lease
affecting the Complex, Tenant shall attorn to the purchaser at such foreclosure
sale or any ground lessor, as the case may be, if requested to do so by such
party, and shall recognize such party as the Landlord, under this Lease, and
Tenant waives the provisions of any statute or rule of law, now or hereafter in
effect, which may give or purport to give Tenant any right to terminate or
otherwise adversely affect this Lease and the obligations of Tenant hereunder
in the event any such foreclosure proceeding is prosecuted or completed.

     (d)  Landlord represents and warrants to Tenant that Landlord owns the
Complex in fee simple and as of the date of the execution and delivery of this
Lease, the Complex is not encumbered by a ground lease or the lien of any
mortgage or deed of trust.

     32.  LANDLORD'S LIEN. Tenant hereby grants to Landlord a lien and security
interest on all property of Tenant now or hereafter placed in or upon the
Premises, and such property shall be and remain subject to such lien and
security interest of Landlord for payment of all rent and other sums agreed to
be paid by Tenant herein. The provisions of this Section relating to such lien
and security interest shall constitute a security agreement under and subject
to Virginia Uniform Commercial Code so that Landlord shall have and may enforce
a security interest on all property of Tenant now or hereafter placed in or on
the Premises, in addition to and cumulative of Landlord's liens and rights
provided by law or by the other terms and provisions of this Lease. Tenant
agrees to execute as debtors such financing statement or statements as Landlord
may now or hereafter request. Landlord may at its election at any time file a
copy of this Lease as a financing statement.

     33.  ATTORNEYS' FEES. In the event either party defaults in the
performance of any of the terms of this Lease and the other party employs an
attorney in connection therewith, the defaulting party agrees to pay the
prevailing party's reasonable attorneys' fees.

     34.  NO IMPLIED WAIVER. No provision of this Lease shall be deemed to have
been waived by Landlord unless such a waiver be in writing signed by Landlord.
The failure of Landlord to insist at any time upon the strict performance of
any covenant or agreement or to exercise any option, right, power or remedy
contained in this Lease shall not be construed as a waiver or a relinquishment
thereof for the future. No payment by Tenant or receipt by Landlord of a lesser
amount than the monthly installment of rent due under this Lease shall be
deemed to be other than on account of the earliest rent due hereunder, nor
shall any endorsement or statement on any check or any letter accompanying any
check or payment of rent be deemed an accord and satisfaction, and Landlord may
accept such check or payment without prejudice to Landlord's right to recover
the balance of such rent or pursue any other remedy in this Lease provided. No
agreement to accept a surrender of this Lease shall be valid unless in a writing

                                       32

<PAGE>   111
signed by Landlord. The receipt by landlord of rent with knowledge of the
breach of any covenant of this Lease shall not be deemed a waiver of such
breach.

     35.  PERSONAL LIABILITY.  The liability of Landlord to Tenant for any
default by Landlord under the terms of this Lease shall be limited to the
interest of Landlord in the Complex, Tenant shall look solely to Landlord's
interest in the Complex for the recovery of any judgment from Landlord, it
being intended that neither Landlord nor any partner or principal of Landlord
nor any other property disclosed or undisclosed of such partners or principals
shall be personally liable for any judgment or deficiency.

     36.  SECURITY DEPOSIT.

     (a)  The Security Deposit shall be held by Landlord as security for the
performance by Tenant of Tenant's covenants and obligations under this Lease,
it being expressly understood that the Security Deposit shall not be considered
as advance payment of rent or a measure of Tenant's damages in case of default
by Tenant. The Security Deposit shall be in the form of an unconditional and
irrevocable letter of credit substantially in the form of Exhibit E attached
hereto, from a federally insured bank in the Washington, D.C. metropolitan
area, with a term coterminous with the Lease Term as it may be extended (or if
required by such bank, in annual installments, the last of which expires no
earlier than the Lease Term as it may be extended), and naming Landlord as
beneficiary. Tenant may at any time substitute cash for the letter of credit.

     (b)  Landlord may from time to time during the continuance of an Event of
Default, without notice to Tenant, draw upon the Security Deposit (either by
drawing upon the letter of credit or withdrawing cash) any amount up to the
amount required to cure the Event of Default, and such draw shall be deemed to
cure the Event of Default, unless Tenant fails timely to perform its obligation
under the next sentence. Landlord shall promptly notify Tenant of any draw on
the Security Deposit pursuant to this subsection (b), and Tenant shall, within
five (5) days of its receipt of such notice, restore the Security Deposit to
the required Security Deposit amount. Tenant's failure to do so shall
constitute a Event of Default hereunder.

     (c)  Within approximately sixty (60) days after the later of the
expiration or earlier termination of the Lease Term, Landlord shall return the
Security Deposit less such portion thereof as Landlord shall have used to
satisfy Tenant's obligations under this Lease.

     (d)  If Landlord transfers the Security Deposit to any transferee of the
Complex or of Landlord's interest therein, then such transferee shall be liable
to Tenant for the return of the Security Deposit. Landlord shall be released
from all liability for the return of the Security Deposit provided such
transferee assumes Landlord's obligations under this Lease. The holder of any
mortgage shall not be liable for the return of the Security Deposit unless such
holder actually receives the Security Deposit.
<PAGE>   112
     (e)  Tenant shall cooperate with Landlord to obtain an amendment or
replacement of the letter of credit if Landlord transfers the Security Deposit
to a new owner of the Building or of Landlord's interest therein or if Landlord
receives notice from the issuer of the letter of credit that the letter of
credit will not be renewed. In such event, Landlord may draw down the letter of
credit, and the cash proceeds thereof shall be held as the Security Deposit in
accordance with this Lease if Tenant does not obtain such amendment or
replacement within twenty (20) days of Landlord's written request therefor. If
at any time, the letter of credit is drawn down pursuant to this subsection
(e), Tenant shall not be deemed in default and may, at Tenant's option, replace
the cash Security Deposit with a new letter of credit substantially in the form
of Exhibit E.

     (f)  Any cash deposited by Tenant as part of the Security Deposit or the
cash drawn by Landlord pursuant to subsection (e) shall be deposited by Landlord
in a federally insured bank. Such account shall bear interest at money market
rates and the interest shall become a part of the Security Deposit. Tenant shall
be responsible for any income tax due for any interest earned on the Security
Deposit. Unless otherwise provided by mandatory non-waivable law or regulation,
Landlord may commingle the Security Deposit with Landlord's other funds. In no
event shall a cash Security Deposit be deemed to be trust funds.

     (g)  Tenant hereby pledges, assigns, conveys, and transfers to Landlord a
lien upon, security title to, a security interest in, and right of setoff
against the Security Deposit and any other money now or hereafter deposited by
Tenant with Landlord. No lien, security title, security interest, or right of
setoff shall be deemed to have been waived by any act or conduct on the part of
Landlord, or by any neglect to exercise such right of setoff or to enforce such
lien, security title or security interest, or by any delay in so doing, and
every lien, security title, security interest, and right of setoff shall
continue in full force and effect until specifically waived or released by an
instrument in writing executed by Landlord.

     (h)  Provided no Event of Default shall have occurred during the first
forty-eight (48) months of the Lease Term and if the Security Deposit has not
already been reduced pursuant to subsection (i) below, the amount of the
Security Deposit shall be reduced to Five Hundred Thousand Dollars ($500,000)
as of the beginning of the forty-ninth (49th) month of the Lease Term, and such
reduced Security Deposit shall be held by Landlord through the expiration of
the Lease Term or any extension thereof in accordance with the terms of this
Lease unless it is further reduced pursuant to subsection (i) below.

     (i)  Provided no Event of Default shall have occurred, at such time as
Tenant maintains a net worth of Five Million Dollars ($5,000,000) for
twenty-four (24) consecutive months, the Security Deposit shall be reduced to
the amount of the Base Rent in effect for the month immediately following the
twenty-fourth (24th) month of such maintenance period. Such reduced Security
Deposit shall be held by Landlord through the expiration of the Lease Term or
any extension thereof in accordance with the terms of this Lease. To
demonstrate that the foregoing stabilized net worth has been attained, Tenant
shall provide Landlord with its audited financial statements covering the
twenty-four (24) month period. The financial statements shall be prepared by a
major independent certified public accounting firm in accordance with generally

                                       34

<PAGE>   113
accepted accounting principles consistently applied. The financial statements
shall demonstrate to Landlord's reasonable satisfaction that Tenant's net worth
is based on, by way of example, such assets as Class A common shares and
retained earnings in lieu of other assets such as convertible stock which would
be convertible in a way which would reduce Net Worth. In evaluating Tenant's net
worth, Landlord may request, and Tenant shall provide, balance sheets, profit
and loss statements and income and expense statements with such detailed
supporting schedules as Landlord may reasonably request.

     37.  FINANCING REQUIREMENTS. In the event that any person, including but
not limited to any bank, insurance company, university, pension or welfare fund,
savings and loan association, real estate investment trust, business trust, or
other financial institution providing financing for the Complex requires, as a
condition of such financing, that modifications to this Lease be obtained,
and provided that such modifications (i) do not adversely affect Tenant's use of
the Premises as herein permitted, (ii) do not materially alter the approved
architectural plans and specifications or the description of Landlord's work in
Exhibit B, and (iii) do not increase the rentals and other sums required to be
paid by Tenant hereunder, Landlord shall submit such required modifications to
Tenant, and if Tenant does not enter into and execute a written amendment hereto
incorporating such required modifications within thirty (30) days after the same
have been submitted to Tenant by Landlord, Landlord shall have the right, at its
sole option, (1) to cancel this Lease, (2) to sign on behalf of Tenant pursuant
to a power of attorney, which is hereby expressly granted to Landlord by Tenant,
or (3) to declare an Event of Default under this Lease. Such options shall be
exercisable by Landlord giving Tenant written notice of the option elected.
Landlord's exercise of any of the foregoing rights may not materially impair
Tenant's use and enjoyment of the Premises or rights under this Lease, nor
materially impair Tenant's ingress and egress to and from the Premises.

     38.  ESTOPPEL CERTIFICATE. Tenant shall, at any time and from time to
time, upon not less than five (5) days' prior written notice by Landlord,
execute, acknowledge and deliver to Landlord a statement in writing (i)
certifying that this Lease is unmodified and in full force and effect (or if
there have been modifications, that the Lease is in full force and effect as
modified and stating the modifications); (ii) stating the dates to which the
rent and any other charges hereunder have been paid by Tenant; (iii) stating
whether or not, to the best knowledge of Tenant, Landlord is in default in the
performance of any covenant, agreement or condition contained in this Lease,
and if so, specifying the nature of such default; (iv) stating that all Tenant
work has been satisfactorily completed, or if not, a list of items excepted;
(v) any other certification reasonably required by Landlord; and (vi) stating
the address to which notices to Tenant are to be sent. Any statement delivered
by Tenant may be relied upon by any owner of the Complex or the land upon
which it is situated, any prospective purchaser of the Complex or such land, or
prospective mortgagee of the Complex or such land or of Landlord's interest
therein, or any prospective assignee of any such mortgagee.

     39.  CERTAIN RIGHTS RESERVED. Landlord hereby reserves to itself and its
successors and assigns the following rights (all of which are hereby consented
to by Tenant): (i) to change the street address and/or name of the Building
and/or the Complex and/or the arrangement and/or location of entrances,
passageways, doors, doorways, corridors, elevators, stairs, toilets,

                                      35
<PAGE>   114
or other public parts of the Building and/or the Complex and to change the
design or configuration of the Building or the Complex; (ii) to erect, use and
maintain pipes and conduits in and through the Premises; and (iii) to grant to
anyone the exclusive right to conduct any particular business or undertaking in
the Building or the Complex. Landlord may exercise any or all of the foregoing
rights without being deemed to be guilty of an eviction, actual or
constructive, or a disturbance or interruption of the business of Tenant or of
Tenant's use or occupancy of the Premises.

     40.  RELOCATION. [intentionally omitted]

     41.  BROKERS. Landlord recognizes Cassidy and Pinkard Property Services,
L.L.C. (formerly known as "Americorp Realty"), and Randall H. Hagner & Company
as the sole brokers procuring this Lease and shall pay said brokers a
commission therefor pursuant to separate agreements between said brokers and
Landlord. Landlord and Tenant each represent and warrant to the other that,
except as provided above, neither of them has employed or dealt with any
broker, agent, or finder in carrying on the negotiations relating to this
Lease. Landlord shall indemnify and hold Tenant harmless, and Tenant shall
indemnify and hold Landlord harmless, from and against any claims for brokerage
or other commissions arising from or out of any breach of the foregoing
representation and warranty by the respective indemnitor. Without limiting the
foregoing, Tenant agrees to, immediately upon demand, pay and/or cause to be
released of record and otherwise any lien filed against the Complex or any
portion thereof by any broker or agent other than those listed above to the
extent of their services provided in procuring this Lease, due to, or allegedly
due to, any action of Tenant, or to post a bond with respect to such lien in an
amount, and upon terms, and with a bonding entity, reasonably satisfactory to
Landlord.

     42.  MISCELLANEOUS.

     (a)  ENTIRE AGREEMENT. This Lease contains and embodies the entire
agreement of the parties hereto, and no representations, inducements, or
agreements, oral or otherwise, not contained in this Lease shall be of any
force or effect. This Lease may not be modified or changed in whole or in part
in any manner other than by an instrument in writing duly signed by the parties
hereto.

     (b)  NO REPRESENTATIONS. Tenant acknowledges that neither Landlord nor any
broker, agent or employee of Landlord has made any representations or promises
with respect to the Premises, the Building, the Complex, or the land on which
the Complex is located, except as herein expressly set forth, and no rights,
privileges, easements or licenses are acquired by Tenant except as herein
expressly set forth.

     (c)  AUTHORITY. Tenant represents and warrants to Landlord that (i) it is
a Delaware corporation duly authorized to conduct business in the Commonwealth
of Virginia and (ii) the person executing this Lease on behalf of Tenant has
been duly authorized to do so.

                                      36
<PAGE>   115
     (d)  NOTICES. Landlord is a nonresident of the Commonwealth of Virginia and
has appointed Edward R. Parker, having an address at c/o CT Corporation, 5511
Staples Mill Road, Richmond, Virginia 23228, as its appointed agent to receive
service of process, notices, orders or demands. All notices or other
communications hereunder shall be in writing and shall be deemed duly given if
(i) delivered in person with a signed receipt therefor, (ii) sent by a
nationally recognized overnight delivery service, such as FedEx, with delivery
fees prepaid or billed to sender, or (iii) sent by certified or registered mail,
return receipt requested, postage prepaid, to the following addresses: (A) if to
Landlord, at SSR Realty Advisors, Inc. (formerly known as MetLife Realty Group,
Inc.), One North Broadway, Suite 500, White Plains, New York 10601, with copy to
Cassidy & Pinkard Property Services, L.L.C., American Center, 8300 Boone Blvd.,
Suite 100, Vienna, Virginia 22182; (B) if to Tenant, before occupancy, at c/o
Asghar D. Mostafa, 10026 Scenic View Terrace, Vienna, Virginia 22182, and after
occupancy at the Premises. Either party may change its address for the giving of
notices by notice given in accordance with this Section.

     (e)  TRANSFERS BY LANDLORD. Landlord shall have the right to transfer and
assign, in whole or in part, all its rights and obligations hereunder and in the
Complex and property referred to herein, and in such event and upon such
transfer, Landlord shall be released from any further obligations hereunder. It
shall be deemed and construed as a covenant running with the land without
further agreement between the parties or their successors in interest, or
between the parties and the transferee of the Complex or of the land on which
the Complex is located that the transferee has assumed and agreed to carry out
any and all covenants and obligations of Landlord hereunder. Tenant agrees to
look solely to such successor in interest of Landlord for the performance of
such obligations.

     (f)  SEVERABILITY. If any term of provision of this Lease, or the
application thereof to any person or circumstances shall, to any extent, be
invalid or unenforceable, the remainder of this Lease, or the application of
such term or provision to persons or circumstances other than those as to which
it is held invalid or unenforceable, shall not be affected thereby, and each
term and provision of this Lease shall be valid and enforceable to the fullest
extent permitted by law.

     (g)  CALENDAR DAYS/BUSINESS DAYS. As used in this Lease and the exhibits
hereto, all references to "days" shall be calendar days unless business days are
specified.

     (h)  SUCCESSORS AND ASSIGNS. The provisions of this Lease shall be binding
upon, and shall inure to the benefit of, the parties hereto and each of their
respective representatives, successors and assigns, subject to the provisions
hereof prohibiting or restricting assignment or subletting by Tenant. If more
than one person is liable under this Lease, the liability of such persons shall
be joint and several.

     (i)  RECORDATION. Tenant agrees not to record this Lease or any memorandum
or copy thereof.

                                       37
<PAGE>   116
     (j)  FORCE MAJEURE. Whenever a period of time is herein prescribed for the
taking of any action by Landlord, Landlord shall not be liable or responsible
for, and there shall be excluded from the computation of such period of time,
any delays due to strikes, riots, acts of God, unusually severe weather,
shortages of labor or materials, acts of war or civil disobedience, the act or
failure to act or any public service or utility provider, governmental laws,
regulations or restrictions, or any other cause whatsoever beyond the control of
Landlord.

     (k)  TIME OF PERFORMANCE. Except as expressly otherwise herein provided,
with respect to all required acts of Landlord and Tenant, time is of the essence
in this lease.

     (l)  NO PARTNERSHIP. Nothing contained in this Lease shall be construed as
creating a partnership or joint venture of or between Landlord and Tenant, or to
create any other relationship between the parties hereto other than that of
Landlord and Tenant.

     (m)  EFFECT OF DELIVERY OF THIS LEASE. Landlord has delivered a copy of
this Lease to Tenant for Tenant's review only, and the delivery hereof does not
constitute an offer to Tenant or option. This Lease shall not be effective until
a copy executed by both Landlord and Tenant is delivered to and accepted by
Landlord.

     (n)  CONSTRUCTION. Tenant acknowledges that Tenant and its representatives
have participated in the negotiation and drafting of this Lease. This Lease
shall not be construed more strictly against Landlord on the grounds that this
Lease has been prepared by Landlord and/or its counsel.

     (o)  COUNTERPARTS. This Lease may be executed in multiple counterparts,
each of which shall be deemed an original and all of which together shall
constitute one and the same document.

     (p)  HEADINGS. Section headings are used herein for the convenience of
reference and shall not be considered when construing or interpreting this
Lease.

     (q)  EXHIBITS. The Exhibits attached hereto (including, without limitation,
the Work Agreement attached hereto as Exhibit B) are incorporated herein and
made a part of this Lease for all purposes.

     (r)  WAIVER OF JURY TRIAL. Landlord and Tenant each hereby waive trial by
jury in any action, proceeding or counterclaim brought by either of them against
the other in connection with any matter arising out of or in any way connected
with this Lease, the relationship of Landlord and Tenant hereunder, Tenant's use
or occupancy of the Premises, and/or any claim or injury or damage.

                                       38
<PAGE>   117
     (s)  CONSENT TO JURISDICTION AND FORUM.  Any litigation in connection
with, or arising out of, this Lease shall be brought in the state or federal
courts for the County of Fairfax, Virginia. Landlord and Tenant hereby consent
to such court's exercise of personal jurisdiction over them. Tenant irrevocably
appoints Michael M. Mannix, Esquire, having an address at Stauffer, Mannix,
Rommel, Decker and Delany, 8300 Greensboro Drive, McLean, Virginia 22102, as
Tenant's agent for receipt of service of process on Tenant's behalf in
connection with any suit, writ, attachment, execution or discovery or
supplementary proceedings in connection with the enforcement of this Lease.
Service shall be effected by any means permitted by the court in which any
action is filed, or, at Landlord's option, by mailing process, postage prepaid,
by certified mail, return receipt requested, either to Tenant's agent at the
foregoing address or to Tenant at Tenant's address set forth in the Section
captioned "Notices". Service shall be deemed effective upon receipt. Tenant may
designate a change of address or agent for purposes of this Section by written
notice to Landlord in accordance with the provisions of the Section captioned
"Notices" at least ten (10) days before such change of address or agent is to
become effective.

     (t)  GOVERNING LAW.  This Lease and the rights and obligations of the
parties hereto shall be interpreted, construed, and enforced in accordance with
the laws of the Commonwealth of Virginia.

     IN WITNESS WHEREOF, Landlord and Tenant have executed this Lease as of the
day and year first above written.

                         TENANT:

WITNESS or ATTEST:       ADVANCED SWITCHING COMMUNICATIONS, INC.,
                          a Delaware corporation

/s/ [illegible]           By: /s/ Asghar D. Mostafa   [SEAL]
---------------------        ----------------------------------
                              Asghar D. Mostafa
                              President and CEO

                        LANDLORD:

WITNESS or ATTEST:       MET LIFE INTERNATIONAL REAL ESTATE EQUITY
                         SHARES, INC.,
                          a Delaware corporation

/s/ [illegible]          By:  /s/ T. Andrew Behymer  [SEAL]
-----------------------       -----------------------
                              Name: T. Andrew Behymer
                              Title: Vice President

                                       39
<PAGE>   118
                             AMERICAN CENTER LEASE

                                LIST OF EXHIBITS

                    EXHIBIT A - Outline of Demised Premises

                    EXHIBIT B - Work Agreement

                    EXHIBIT C - Declaration of Commencement Date

                    EXHIBIT D - Rules & Regulations

                    EXHIBIT E - Form of Letter of Credit

                                       40

<PAGE>   119
                                   EXHIBIT A

                          OUTLINE OF DEMISED PREMISES

<PAGE>   120
                                   EXHIBIT B
                                 WORK AGREEMENT

     This Work Agreement governs the terms and conditions for the design and
reconstruction of the existing tenant improvements for Tenant's use (the
"Tenant Improvements") and the Schedule of Responsibilities (as hereinafter
defined) for Landlord and Tenant to complete the Tenant Improvements.

     Unless otherwise specifically provided in this Work Agreement, all
capitalized terms in this Work Agreement shall have the meanings ascribed
thereto in the Lease. This Work Agreement is incorporated by reference into the
Lease. In the event of any inconsistencies between this Work Agreement and
other terms of the Lease, the terms of this Work Agreement shall control and
take precedence.

     1.  SPACE PLAN.  Attached hereto is as Exhibit B-1 and made a part hereof
by this reference are the Space Plan and Construction Specifications
(collectively, the "Space Plan") prepared by The M Group and approved by Tenant
and Landlord for the Tenant Improvements for the renovation of the Phase I
Space and the Phase II Space.

     2.  EXISTING CONDITION OF THE PREMISES.  Tenant acknowledges that Tenant
has thoroughly inspected the Premises. In preparing the Space Plan, Tenant has
taken into account the condition of the Premises as of the date of the Lease
and accepts the Premises in their "as is" condition, except latent defects.

     3.  TURN-KEY CONSTRUCTION.

     (a) Landlord shall construct the Tenant Improvements shown on the Space
Plan on a turn-key basis (including payment for the Space Plan, Working
Drawings (as hereinafter defined), and building permits) at no charge to
Tenant. The Space Plan includes allowances (the "Allowances") for certain
fixtures and materials and the related labor costs that will be provided as
part of the Tenant Improvements.

     (b) In the event Tenant elects to improve the Premises with materials the
quality or quantity of which is in excess of the Allowances for such materials
specified in the Space Plan and such materials and/or the additional labor
required will result in a higher cost to Landlord, the cost of such
improvements (the "Excess Improvements") shall be a Tenant Cost (as hereinafter
defined). Tenant shall not be entitled to any credit in the event Tenant elects
to use materials the quantity or cost of which is less than the Allowances
therefor.

     (c) Tenant shall incur no cost for the Tenant Improvements provided that
none of the Allowances are exceeded, there are no Excess Improvements, and
there are no Tenant Delays (as hereinafter defined). Tenant shall not be
allowed any credit for unused Allowances.

     (d) Any amount that Tenant is required to pay under this Agreement shall
be referred to as a "Tenant Cost". Any Tenant Costs shall be deemed rent under
the Lease. Landlord may reasonably estimate Tenant Costs in advance, in which
case, Tenant shall deposit such estimated amount with Landlord. If such
estimated amount exceeds the actual amount of the Tenant Costs, Tenant shall
receive a refund of the difference. If the actual amount shall exceed the
estimated amount, Tenant shall pay the difference to Landlord within ten (10)
days after receipt of an invoice therefor from Landlord.

     4.  WORKING DRAWINGS.

     (a) Working drawings (the "Working Drawings") for the Tenant Improvements
shall comprise the final architectural, mechanical and electrical plans and
specifications approved by Landlord and Tenant, which shall be the basis for
performance of all work in the Premises

<PAGE>   121
herein contemplated. Except as described below, the Working Drawings shall be
at 1/8" = 1' scale and will include architectural and engineering drawings and
specifications as well as notes necessary for pricing, permits and construction
and calculations of quantities of items. Working Drawings will include but not
be limited to the following, if applicable:

     (i)  partition plan at 1/8" scale;

    (ii)  reflected ceiling and lighting plan;

   (iii)  electrical and telephone outlet plan;

    (iv)  mechanical and plumbing plan;

     (v)  finish and color schedule;

    (vi)  door and hardware schedule including jamb details at 1-1/2"
          scale for doors and/or jambs if required; and

   (vii)  all other architectural and engineering detail drawings and
          specifications reasonably necessary to accomplish the work including
          detailed representation and/or elevations of all special conditions
          at 1-1/2" scale.

     (b)  Promptly after the execution and delivery of the Lease, Landlord's
architect and engineer shall commence preparation of the Working Drawings,
which shall be based on the Space Plan. Landlord's contractor, PCW
Construction, Inc. ("Landlord's Contractor"), shall deliver the Working
Drawings to Tenant for written approval promptly after any pricing relating to
Excess Improvements in the Space Plan have been determined. Within seventy-two
(72) hours after Tenant's receipt of the Working Drawings, Tenant shall notify
Landlord in writing whether (i) Tenant desires any changes in the Working
Drawings and (ii) Tenant's approval or conditional approval of the Working
Drawings. If Tenant has requested pricing for Excess Improvements, Tenant shall
also notify Landlord in writing that the pricing therefor is acceptable and
that Tenant acknowledges its obligation to pay for the Excess Improvements as a
Tenant Cost and Tenant will deposit the cost therefor with Landlord.

     (c)  If Tenant fails to approve or disapprove the Working Drawings or the
cost of the Excess Improvements, if any, within seventy-two (72) hours, then
(i) Landlord's deadline for Substantial Completion (as hereinafter defined)
pursuant to the Schedule of Responsibilities attached hereto as Exhibit B-2 and
made a part hereof by this reference shall be extended by the number of days or
hours from the time specified in the Schedule of Responsibilities for Tenant's
approval of the Working Drawings and/or the Tenant Costs until the pricing is
finally acceptable to Tenant, and such number of days or hours shall be a
Tenant Delay (as hereinafter defined) and (ii) any redesign costs that may be
incurred as a result of changes requested by Tenant in the Working Drawings
outside of the scope of the Space Plan shall be a Tenant Cost. Upon Tenant's
approval of the Working Drawings and, if there are any Tenant Costs, upon
Tenant's payment of any deposits with Landlord, Landlord's Contractor shall
commence construction of the Tenant Improvements.

     5.  SUBSTANTIAL COMPLETION.  Landlord's Contractor shall achieve
"Substantial Completion" of the Tenant Improvements in accordance with the
Lease and the Schedule of Responsibilities attached hereto as Exhibit B-2. As
used in this Work Agreement, the Tenant Improvements shall have achieved
Substantial Completion if all of the work called for under the Working Drawings
has been substantially completed in accordance with Landlord's construction

                                      B-2

<PAGE>   122
contract with Landlord's Contractor and Landlord has received the final
inspection authorizing Tenant to take occupancy of the Premises. Substantial
Completion does not include completion of (i) details of construction,
decoration or adjustment which do not substantially interfere with Tenant's
occupancy or the ability of any specialty contractors hired by Tenant to install
fixtures or equipment Tenant has ordered; (ii) any punch list work which does
not affect Tenant's use of the Premises and which can be completed or corrected
as soon as reasonably possible after the Phase I Commencement Date or the Phase
II Commencement Date; (iii) items for which Tenant requests a deferral; and/or
(iv) any long-lead or specialty items required by Tenant. Landlord will give
Tenant no less than ten (10) days' advance written notice of the anticipated
date of Substantial Completion so that Tenant can be prepared to take occupancy
of the Premises on or immediately after the date of Substantial Completion.
Landlord will cooperate with Tenant in allowing Tenant's specialty contractors,
if any, to enter the Premises during said ten-day period to complete work needed
before Tenant will take occupancy.

     6.   PUNCH LIST WORK. Prior to delivery of possession of the Premises to
Tenant, Landlord, Tenant, and Landlord's Contractor shall make a final
inspection of the Premises to make certain that the work has been accomplished
according to Working Drawings as amended by any approved changes. A punch list
of items to be completed or corrected shall be prepared as agreed by the
parties, and Landlord's Contractor shall correct such punch list items. If
Tenant, Tenant's agents or employees, and/or any person(s) directly or
indirectly employed by Tenant places furniture, equipment, appliances or any
other items in the Premises and/or any of Tenant's specialty contractors
commence work prior to Landlord's compilation of a punch list regarding any
involved areas of the Premises or the Complex or Common Areas, any damages to
any work in place for which there exists a reasonable doubt as to the party
responsible for such damages shall be deemed to have been caused by Tenant
and/or any persons directly or indirectly employed by Tenant, and Landlord
and/or Landlord's Contractor shall not be held responsible for any costs or
expenses related to or resulting from correction of same.

     7.   SCHEDULE OF RESPONSIBILITIES.

          (a)  DELAYS. Landlord, Tenant, Landlord's Contractor, and/or any
specialty contractors hired by Tenant shall each strictly abide by all dates set
forth for their respective activities in the Schedule of Responsibilities (the
"Schedule of Responsibilities") attached hereto as Exhibit B-2 > and made a part
hereof. Any delay in making such decisions shall be a Tenant Delay. Deadlines
for Landlord's Contractor shall be deemed to be deadlines for Landlord, and any
delays caused by Landlord's Contractor shall be deemed to be delays caused by
Landlord ("Landlord Delays"). Deadlines for Tenant and/or Tenant's specialty
contractors, if any, shall be deemed to be deadlines for Tenant, and any delays
caused by said persons or entities shall be deemed to be delays caused by Tenant
("Tenant Delays"). If Tenant fails to meet any of its deadlines pursuant to the
Schedule of Responsibilities, then each of Landlord's subsequent deadlines shall
be extended by the number of days by which Tenant missed its deadlines. If
Landlord fails to meet any of its deadlines, then each of Tenant's subsequent
deadlines shall be extended by the number of days by which Landlord misses its
deadlines. If Landlord Delays exceed Tenant Delays by more than thirty (30)
days, Landlord shall be liable for the penalty described in Section 7(g) below.

          (b)  DECISIONS DURING COURSE OF CONSTRUCTION. Tenant acknowledges that
the construction schedule for Substantial Completion of the Tenant Improvements
will require that Tenant make all decisions about carpet color, paint color, and
other details of design and construction no later than twenty-four (24) hours
after Landlord's Contractor's request for a decision.

                                      B-3

<PAGE>   123
          (c)  TENANT'S AGENT. In light of the short schedule under which all
parties involved in construction will be working and the need for immediate
decision-making, Tenant hereby appoints the persons below as Tenant's agents
for purposes of authorizing and executing any and all documents needed to
effect this Work Agreement, and any and all changes, additions or deletions to
the work contemplated herein. Landlord shall have the right to rely on any
documents executed by such authorized persons, and either person is fully
authorized to bind Tenant.

                         Asghar D. Mostafa
                         10026 Scenic View Terrace
                         Vienna, Virginia 22182
                         Telephone: (703) 307-2057
                         FAX: (703) 759-5303.

          (d)  FORCE MAJEURE. All deadlines for all parties hereunder shall be
subject to, and extended by, force majeure which shall mean, but not be
limited to, strikes, lockouts or labor disputes, inability to obtain labor or
materials or reasonable substitutes therefor (other than specialty or long-lead
items), acts of God, enemy or hostile governmental action, civil commotion,
abnormally severe weather conditions preventing construction work in the
Premises to proceed in spite of reasonable efforts, fire or other casualty
beyond the reasonable control of Landlord or Tenant and not due to the fault or
negligence of Landlord, Tenant or the agents, contractors, licensees or
employees of either of them.

          (e)  CHANGES. In the event of any changes requested by Tenant to the
Working Drawings, which changes constitute changes to Tenant's previous
instructions specified in the Space Plan, any delays caused by such changes
shall be a Tenant Delay and any redesign costs or costs for additional labor
and/or materials shall be a Tenant Cost. Tenant shall also be fully responsible
as a Tenant Cost for: (i) the costs of any demolition of completed or partially
completed work previously commenced; (ii) the costs, if any, of work in place
and of cancelling any materials ordered and/or received; (iii) the costs of any
redesign required; and (iv) any delays in achieving Substantial Completion of
the work caused by any or all of the above, including any time expended between
the time Landlord's Contractor is told to stop work in a particular area and
the time Landlord's Contractor is then eventually released. Landlord shall not
be required, nor shall Tenant's specialty contractors, if any, be permitted, to
commence work on any such changes until Tenant has approved in writing, the
Tenant Costs (including construction and design) and the time delays
attributable thereto and paid to Landlord the Tenant Costs due. Notwithstanding
the foregoing, Tenant shall have no more than twenty-four (24) hours to approve
the costs and delay attributable to such changes after Tenant's receipt of the
change order therefor. In the event Tenant shall not respond within this time,
Tenant shall be deemed to have approved said costs and delay.

     (f)  COMMENCEMENT DATES. The Phase I Commencement Date and the Phase II
Commencement Date shall be the date of Substantial Completion of the Phase I
Space and the Phase II Space, as applicable, minus the total number of days
comprising Tenant Delays plus the total number of days comprising Landlord
Delays. Landlord will build out the Phase II Space without all of the demising
walls at the same time the Phase I Space is built out. If Landlord leases the
Phase II Space to another tenant prior to the Phase II Commencement Date,
Landlord shall deliver the Phase II Space in "as is" condition, broom clean,
provided that the Phase II Space complies with the Working Drawings therefor.

                                      B-4

<PAGE>   124
          (g)  LANDLORD DELAY PENALTY.  In the event Landlord Delays exceed
Tenant Delays by more than thirty (30) days, for each day of Landlord Delays
thereafter. Landlord shall abate and forgive two (2) days of Base Rent
commencing with the first payment due as of the Phase I Commencement Date or
the Phase II Commencement Date as applicable.

     8.   TIME OF THE ESSENCE. Time is of the essence of the obligations of
Landlord and Tenant under this Work Agreement. All days in this Work Agreement
are calendar days.

     9.   MISCELLANEOUS.

          (a)  DESIGN/CONSTRUCTION/MATERIAL WARRANTIES.  Tenant acknowledges
that Landlord is not an architect or engineer and that the Tenant Improvements
will be designed and performed by independent architects, engineers and
contractors. Accordingly, Landlord does not guarantee or warrant that the Space
Plan or Working Drawings will be free from errors or omissions nor that the
Tenant Improvements will be free from defects. In the event of such errors,
omissions, or defects, Landlord shall cooperate in any action Tenant desires to
bring against such parties. Landlord shall seek to enforce any warranties it
obtains from any architect, engineer or contractor for the benefit of Tenant.
If a judgment is entered against Landlord for such errors, omissions, or
defects of Landlord's architects, engineers or contractors, Tenant's damages
shall be limited to the cost of reconstructing the Tenant Improvements to
correct the error or omission in the Space Plan or Working Drawings or the
defect in the Tenant Improvements.

          (b)  GOVERNMENTAL APPROVALS.  Landlord shall, at its cost, apply for
the normal building permits required for the Tenant Improvements described in
the Working Drawings and issued pursuant to the local building code as a
ministerial matter. If the Working Drawings must be revised in order to obtain
such building permits, Landlord shall promptly notify Tenant. Landlord shall
promptly have the Working Drawings revised within seventy-two (72) hours to
satisfy the building permit requirements and shall submit the revised Working
Drawings to Tenant for written approval. Tenant shall provide such written
approval within twenty-four (24) hours. In such event, the Schedule of
Responsibilities shall be revised to reflect a delay in Substantial Completion,
but such delay shall be neither a Landlord Delay nor a Tenant Delay.

     IN WITNESS WHEREOF, Landlord and Tenant have executed this Work Agreement
as of even date with the Lease.

                                   TENANT:

WITNESS or ATTEST:                 ADVANCED SWITCHING COMMUNICATIONS, INC.,
                                     a Delaware corporation

/s/ [illegible]                    By: /s/ Asghar D. Mostafa          [SEAL]
-------------------------              -------------------------------
                                       Asghar D. Mostafa
                                       President and CEO

                                   LANDLORD:

WITNESS or ATTEST:                 MET LIFE INTERNATIONAL REAL ESTATE EQUITY
                                   SHARES, INC.,
                                     a Delaware corporation

/s/ [illegible]                    By: /s/ T. Andrew Behymer          [SEAL]
-------------------------              -------------------------------
                                       Name: T. Andrew Behymer
                                             Vice President

                                      B-5
<PAGE>   125
                                  EXHIBIT B-2
                          SCHEDULE OF RESPONSIBILITIES

<TABLE>
<CAPTION>
                                                       DATE
<S>  <C>                                     <C>
1.   Lease executed and delivered.           September __, 1997

2.   Tenant gives written approval of        Seventy-two (72)
     Working Drawings (and Tenant Costs,     hours after Tenant's
     if any) in connection therewith and     receipt of Working
     deposits Tenant Costs with Landlord.    Drawings

3.   Tenant's specialty contractors allowed  Ten (10) days before
     into Premises to install fixtures and   date of Substantial
     equipment in Phase I Space.             Completion

4.   Substantial Completion of Tenant        December 1, 1997
     Improvements for the Phase I Space.
</TABLE>

<PAGE>   126
ASC, Inc.
8330 Boone Boulevard, Fifth Floor
Vienna, Virginia 22182

To be attached to space Plan Dated September 15, 1997

The estimator shall visit the site before submitting any pricing.

1.) Perform all demolition as indicated or as necessary for the new plan. New
    partitions shall be 5/8" gypsum board on both sides of 2 1/2" metal studs.
    The partitions around the Conference rooms and the CEO and COO offices
    shall contain sound insulation and extend to the deck above.

2.) The Pantries, coffee stations and the Copy/File room shall receive new VCT
    and vinyl base. The elevator lobby, CEO, COO offices, Reception area,
    Seating and the conference rooms shall receive new upgraded carpet on pad.
    The remainder of the space shall receive new building standard carpet on
    pad and new vinyl base.

3.) Except as noted, the entire space shall be painted. Remove any existing
    wall covering and prepare the walls for paint as necessary. Provide wall
    covering in the Conference rooms and the Reception and CEO area. All $1.20
    per square foot for wall covering material (only. Contractor to determine
    material quantities and cost necessary to apply the wall covering.)

4.) Repair the existing ceiling grid as necessary. Replace any damaged ceiling
    tiles or tiles that no longer match the remainder of the space. Provide a
    gypsum board on metal stud soffit at the reception area over the logo sign.

5.) New interior doors shall be building standard laminate doors in building
    standard metal frames. Provide new lever hardware as required for ADA on
    all new doors and all existing doors not already so equipped. Match
    finishes and function of existing hardware. Provide electric strikes at
    four locations for the Tenant supplied security system.

6.) Clean and/or repair all existing window blinds as necessary.

7.) Lighting shall be reconfigured to accommodate the new plan. Provide 30
    building standard recessed incandescent down lights and 10 building
    standard recessed incandescent wall washing down lights, location to be
    determined at a later date.

8.) Reconfigure the HVAC as necessary to accommodate the new plan. The Network
    Workroom requires additional cooling for the anticipated equipment load.
    Reuse the existing supplemental air conditioning if possible and supplement
    as necessary. It is not required to supplemental air conditioning if
    possible and supplement as necessary. It is not required to provide 24 hour,
    7 day conditioning. The mechanical modifications include:

    a) Provide a nominal VAV self contained glycol cooled upflow air
       conditioning unit, with the capacity of 1/2 ton per 100 USF in Network
       Workroom Liebert model UH363G, with the following:

       i)   460v-3ph
       ii)  30kw reheat coil
       iii) 7.2 ks steam generating humidifier with one extra disposable
            canister
       iv)  20% efficiency standard 4" filter
       v)   standard microprocessor control
       vi)  non-locking disconnect switch
       vii) condensate pump

<PAGE>   127
         viii) smoke detector
           ix) supply plenum w/o side grilles
            x) glycol regulating valve
           xi) 7/24 temperature and humidity recorder
     b)   Provide dry cooler Liebert model DD-0466 with the following:
            i) Dual pump package
           ii) Expansion tank
          iii) Locking disconnect switch
           iv) Fan cycling controls
            v) 460V-3ph
     c)   If existing piping is 3" or greater, it may be used to what
          extent is feasible. If not feasible, provide 3" type L copper
          piping with wrought copper fittings. Provide:
     d)   valves and fittings as recommended by the manufacturer at the air
          conditioning units and dry cooler
     e)   all hangers and supports

9.)  Electrical power shall be reconfigured for the new plan. Typical perimeter
     offices shall have power and data outlets on each of the side walls.
     Additional outlets shall be provided as necessary to meet this requirement.
     The work stations shall require junction boxes and, in some locations,
     core drills providing 4 circuit, 8 wire with isolated ground service (4
     hots, 2 neutrals, one ground and one isolated ground). The Contractors;
     electrician shall connect the Tenant supplied work stations. Electrical
     requirements in the Network Workroom will require upgrades as follows:
     a) 200 Amp., 277/480 Volt, 3 phase, 4 wire feeder from the main electrical
        room with a sub meter.
     b) Panel "DP" 225 Amp., 277/480 Volt, 3 phase, 4 wire panelboard with 1-3
        Pole 30 Amp. 1-3 Pole 100 Amp and 1-3 Pole 200 Amp breakers
     c) 112.5 KVA Amp and 1-3 Pole 200 Amp breakers 112.5 KVA transformer - 480
        Volt, 3 phase, 3 wire to 120.208 Volt, 3 Phase, 4 wire
     d) Panel "L"-400 Amp., 120.208 Volt, 3 Phase 4 wire two section panelboard
        with 400 Amp main breaker with feed thru lugs:
                 (i) 1st section 42 - 1 Pole 20 Amp. Breakers.
                (ii) 2nd section 39 - 1 Pole 20 Amp. And 1-3 Pole 100 Amp.
                     Breakers
     e) Panel "LA" - 100 Amp., 120.208 Volt, 3 Phase, 4 wire with 14-1 Pole, 20
        Amp. And 5-2 Pole 20 Amp. Breakers and isolated ground bus with #6
        isolated ground to building service entrance ground.

10.)    Data and communication outlets shall provide a gypsum board trim ring
        and pull string to facilitate cable installation by the Tenant's
        contractor, Provide a plastic grommet in the top runner of the metal
        studs above the ring and string locations.
11.)    Base and wall cabinets in the Coffee stations and the Pantries shall be
        "Avia" by Merillat. Provide plastic laminate on MDF counter tops, back
        and side splash. The ledge below the logo sign shall be plastic
        laminate on MDF scribed to the wall with custom laminate cabinets
        below. The cabinets and counter top in Pantry 2 shall be repaired to
        like new appearance.
12.)    The glass in the two Conference rooms shall be tempered "Herculite"
        style in 4" top and bottom polished metal rails with silicon
        vertical joints. The glass into the Network Workroom shall be tempered
        in polish metal top and bottom channels with silicon vertical joints
        and start 3'-6" AFF and extend to the ceiling.
13.)    Provide electric black-out drapes in the Conference rooms on both the
        interior and exterior windows.

<PAGE>   128
14.)  Provide an electric operating recessed projection screen in both
      Conference rooms similar to Da-Lite Board room Electrol. 70" x 70" with
      High Power viewing surface.
15.)  Provide a data and telephone cable allowance not to exceed $1.25 per
      square foot (no terminations).
16.)  Provide an allowance not to exceed $.50 psf for Reception area millwork.
      (Desk)
17.)  Provide an allowance not to exceed $3,000.00 for Reception area sign.
18.)  Provide two microwave ovens and two full size refrigerators with ice
      makers.

AGREED TO AND ACCEPTED:

TENANT:                                 LANDLORD:

/s/   A.D. Mostafa                      /s/  T. Andrew Behymer
__________________________              ____________________________
By                                      By

   President & CEO                           Vice President
__________________________              ____________________________
Title                                   Title

       9/19/97                                    9/19/97
__________________________              ____________________________
Date                                    Date

<PAGE>   129
                                   EXHIBIT C
                        DECLARATION OF COMMENCEMENT DATE

     NOTE: THIS DOCUMENT SHALL BE EXECUTED AFTER EACH OF THE PHASE I
     COMMENCEMENT DATE AND THE PHASE II COMMENCEMENT DATE HAVE BEEN
     DETERMINED.

     THIS DECLARATION OF COMMENCEMENT DATE is made as of the ___ day of
______________, 199__, by and between MET LIFE INTERNATIONAL REAL ESTATE
EQUITY SHARES, INC., a Delaware corporation ("Landlord"), and ADVANCED
SWITCHING COMMUNICATIONS, INC., a Delaware corporation ("Tenant").

                                    RECITALS

     A.  Landlord and Tenant entered into that certain Deed of Lease (the
"Lease") dated as of September __, 1997, for the lease of certain Premises (as
defined in the Lease) in that certain office building located at 8330 Boone
Blvd., Vienna, Virginia, in the complex known as "American Center".

     B.  The Lease provides that after the [PHASE I][PHASE II] Commencement
Date has been determined, Landlord and Tenant shall enter into a written
declaration setting forth the [PHASE I][PHASE II] Commencement Date and the
date upon which the Lease Term (as defined in the Lease) will expire.

     NOW, THEREFORE, in consideration of the mutual promises contained herein
and in the Lease and other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, Landlord and Tenant hereby agree
as follows:

     1.  The [PHASE I][PHASE II] Commencement Date is _________________, 199_,
and the Lease Term shall expire on _______________, unless terminated earlier
or extended in accordance with the terms of the Lease.

     2.  The improvements and space required to be furnished to Tenant under
the terms of the Lease and all other matters required to be furnished or
performed by Landlord have been completed in all respects in accordance with
the terms of the Lease. Tenant acknowledges that Tenant has had an opportunity
to inspect the Premises and accepts the Premises in their condition "as is".

     3.  All duties of Landlord of an inducement nature have been fulfilled and
all other obligations required to be performed or observed by Landlord have
been duly and fully performed or observed by Landlord.

     4.  Landlord has not waived the performance or observance by Tenant of any
of the terms, covenants, or conditions to be performed or observed by Tenant
under the Lease.

<PAGE>   130
Landlord has made no representations or commitments, oral or written, or
undertaken any obligations other than as may be expressly set forth in the
Lease.

     5. Except as amended by this Declaration, the Lease continues in full
force and effect in accordance with its terms and is enforceable against
Landlord and Tenant in accordance with its terms. No claim, set-off or defense
exists for the benefit of Tenant against Landlord in connection with the Lease,
and to the extent any claims, set-offs or defenses exist, they are hereby
waived and relinquished in their entirety.

     IN WITNESS WHEREOF, Landlord and Tenant have executed this Declaration of
Commencement Date as of the date first above written.

                         LANDLORD:

WITNESS or ATTEST:       MET LIFE INTERNATIONAL REAL ESTATE EQUITY
                         SHARES, INC.,
                         a Delaware corporation

_______________________  By:  ________________________________ [SEAL]
                               Name:
                               Title:

                         TENANT:

WITNESS or ATTEST:       ADVANCED SWITCHING COMMUNICATIONS, INC.,
                         a Delaware corporation

_______________________  By:  _________________________________[SEAL]
                               Asghar D. Mostafa
                               President and CEO

                                C-2

<PAGE>   131
                                   EXHIBIT D
                             RULES AND REGULATIONS

1.   Sidewalks, doorways, vestibules, halls, stairways, and similar areas shall
not be obstructed nor shall refuse, furniture, boxes or other items be placed
therein by Tenant or its officers, agents, servants, and employees, or used for
any purpose other than ingress and egress to and from the Premises, or for going
from one part of the Building or Complex to another part of the Building or
Complex. Canvassing, soliciting and peddling in the Complex are prohibited.

2.   Plumbing fixtures and appliances shall be used only for the purposes for
which constructed, and no unsuitable material shall be placed therein.

3.   No signs, directories, posters, advertisements, or notices shall be painted
or affixed on or to any of the windows or doors, or in corridors or other Common
Areas of the Complex, except in such color, size, and style, and in such places,
as shall be first approved in writing by Landlord in its reasonable discretion.
One building standard suite identification sign will be prepared by Landlord at
Landlord's expense. No additional signs shall be posted without Landlord's prior
written consent as to location and form, and the cost of preparing and posting
such signs shall be borne solely by Tenant. Landlord shall have the right to
remove all unapproved signs without notice to Tenant, at the expense of Tenant.

4.   Tenants shall not do, or permit anything to be done, in or about the
Complex, or bring or keep anything therein, that will in any way increase the
rate of fire or other insurance on the Complex, or on property kept therein or
otherwise increase the possibility of fire or other casualty.

5.   Landlord shall have the power to prescribe the weight and position of heavy
equipment or objects which may overstress any portion of the floor. All damage
done to the Building by the improper placing of such heavy items will be
repaired at the sole expense of the responsible tenant.

6.   Tenant shall notify the manager of the Complex when safes or other heavy
equipment are to be taken in or out of the Building, and the moving shall be
done after written permission is obtained from Landlord on such conditions as
Landlord shall require. Any moving in or moving out of Tenant equipment,
furniture, files, and/or fixtures shall be done only with prior written notice
to Landlord, and Landlord shall be entitled to prescribe the hours of such
activity, the elevators which shall be available for such activity and shall, in
addition, be entitled to place such other reasonable conditions upon Tenant
moving activities as Landlord deems appropriate. Tenant shall bear all risk of
loss relating to damage incurred with respect to Tenant's property in the
process of such a move, and in addition, shall indemnify and hold Landlord
harmless as to all losses, damages, claims, causes of action, costs and/or
expenses relating to personal injury or property damage sustained by Landlord or
any third party on account of Tenant moving activities.

7.   Corridor doors, when not in use, shall be kept closed.
<PAGE>   132
8.   All deliveries must be made via the service entrance and elevators,
designated by Landlord for service, if any, during Normal Business Hours.
Landlord's written approval must be obtained for any delivery after Normal
Business Hours.

9.   Each tenant shall cooperate with Landlord's employees in keeping its
premises neat and clean.

10.  Tenant shall not cause or permit any improper noises in the Building or the
Complex or allow any unpleasant odors to emanate from the Premises, or otherwise
unreasonably interfere, injure or annoy in any way other tenants or persons
having business with them.

11.  Except for seeing-eye dogs, no animals shall be brought into or kept in or
about the Building or the Complex.

12.  No boxes, crates or other such materials shall be stored in hallways or
other Common Areas. When Tenant must dispose of crates, boxes, or similar
refuse, it will be the responsibility of Tenant to dispose of same prior to 7:30
a.m. or after 6:00 p.m., respectively, so as to avoid having such debris visible
in the Common Areas during Normal Business Hours.

13.  No machinery of any kind, other than ordinary office machines such as
personal computers, calculators, fax machines, and similar standard office
equipment shall be operated in the Premises without the prior written consent of
Landlord, nor shall a tenant use or keep in the Complex any flammable or
explosive fluid or substance (including Christmas trees). No space heaters or
fans shall be operated in the Premises.

14.  No bicycles, motorcycles or similar vehicles will be allowed in the
Complex, except in areas that may be designated by Landlord.

15.  No nails, hooks or screws shall be driven into or inserted in any part of
the Premises except customary picture frames or as otherwise approved by the
manager of the Complex. Nothing shall be affixed to, or made to hang from, the
ceiling of the Premises without Landlord's prior written consent.

16.  Landlord has the right to evacuate the Complex in the event of an emergency
or catastrophe.

17.  No food and/or beverages shall be distributed from Landlord's office
without the prior written approval of the manager of the Complex.

18.  No additional locks shall be placed upon any doors without the prior
written consent of Landlord. All necessary keys shall be furnished by Landlord,
and the same shall be surrendered upon termination of this Lease, and Tenant
shall then give Landlord or his agent an explanation of the combination of all
locks on the doors or vaults. Tenant shall initially be given ten (10)

                                      D-2
<PAGE>   133
keys to the Premises by Landlord. No duplicates of such keys shall be made by
Tenant. Additional keys shall be obtained only from Landlord, at a fee to be
determined by Landlord.

19. Tenant will not locate furnishings or cabinets adjacent to mechanical or
electrical access panels so as to prevent operating personnel from servicing
such units as routine or emergency access may require. The cost of moving such
furnishings for Landlord's access will be for Tenant's account. The lighting
and air conditioning equipment of the Complex will remain the exclusive charge
of the personnel designated by the manager of the Complex.

20. Tenant shall comply with parking rules and regulations as may be posted and
distributed from time to time.

21. No portion of the Complex shall be used for the purpose of lodging rooms.

22. Vending machines or dispensing machines of any kind will not be placed in
the Premises by Tenant.

23. Prior written approval, which shall be at Landlord's sole discretion, must
be obtained for installation of window shades, blinds, drapes, or any other
window treatment of any kind whatsoever. Landlord will control all internal
lighting that may be visible from the exterior of the Complex and shall have
the right to change any unapproved lighting, without notice to Tenant, at
Tenant's expense.

24. Landlord hereby designates the following days as Normal Business Holidays
(on the dates observed by the federal government), on which days services will
not be provided and normal operating hours will not be followed:

                                 New Year's Day
                    Washington's Birthday (Presidents' Day)
                         Martin Luther King's Birthday
                                  Memorial Day
                                Independence Day
                                   Labor Day
                                  Columbus Day
                                  Veterans Day
                                Thanksgiving Day
                                 Christmas Day

Landlord reserves the right, at its sole option, to designate as a Normal
Business Holiday (i) any other legal public holiday if so promulgated pursuant
to Title 5, Section 6103 of the United States Code or by the Commonwealth of
Virginia; (ii) the Friday after Thanksgiving Day if Landlord reasonably
determines that many occupants of the Complex will be observing that day as a
holiday; and (iii) such other days designated as legal holidays by the
applicable building service union employees' service contract and/or by the
applicable operating engineer's contract.

                                      D-3
<PAGE>   134
25. No smoking is permitted in the Premises or the Common Areas.

26. Landlord reserves the right to rescind any of these rules and make such
other and further reasonable rules and regulations as in its reasonable
judgment shall from time to time be needful for the subject to operation of the
Complex subject to the terms of this Lease, which rules shall be binding upon
each Tenant upon delivery to such Tenant of notice thereof in writing.

                                      D-4
<PAGE>   135
                                  EXHIBIT E

                           FORM OF LETTER OF CREDIT

                    IRREVOCABLE LETTER OF CREDIT NO. ___

                             September __, 1997

Met Life International Real Estate Equity Shares, Inc.
c/o SSR Realty Advisors, Inc.
Authorized Agent
One North Broadway
Suite 500
White Plains, New York 10601

Gentlemen:

     We hereby establish in favor of Met Life International Real Estate Equity
Shares, Inc. ("Beneficiary"), a Delaware corporation, for the account of
Advanced Switching Communications, Inc., our Irrevocable Letter of Credit in
the amount of ONE MILLION AND NO/100 DOLLARS ($1,000,000.00), effective
immediately and expiring with our close of business on the _____ day of
September, 1998. It is a condition of this Letter of Credit that it will be
automatically extended for additional consecutive periods of one year each from
the present or future expiration date unless you receive from us within sixty
(60) days prior to such date, in writing by registered mail at the above
address, that we elect not to renew this Letter of Credit for such additional
period.

     Funds under this Letter of Credit are available to you against your sight
draft drawn on us, marked thereon "Drawn under Irrevocable Letter of Credit No.
______" and presented to us at our office at _____________________, accompanied
by your statement addressed to us in the form attached hereto and incorporated
herein as Attachment A.

     We will accept such statement as binding and correct without having to
investigate or having to be responsible for the accuracy, truthfulness, or
validity thereof or any part thereof and notwithstanding the claim of any
person to the contrary.

     We hereby agree with you that the draft drawn in accordance with the terms
and conditions of this Letter of Credit will be honored before the close of the
third banking day following receipt of the aforesaid draft and statement if
presented to us on or before the applicable expiration date in accordance with
applicable provisions of the Uniform Commercial Code then in effect in the
Commonwealth of Virginia.

     Unless otherwise stated, this Letter of Credit is subject to the Uniform
Customs and Practices for Documentary Credits (1993 Revision), International
Chamber of Commerce Publication No. 500).

                                       Very truly yours,

<PAGE>   136
                                "ATTACHMENT A"

     Attached to and made a part of Irrevocable Letter of Credit No. ______
(the "Letter of Credit") dated September __, 1997, issued by ____________, to
Met Life International Real Estate Equity Shares, Inc. ("Beneficiary"), a
Delaware corporation, for the account of Advanced Switching Communications, Inc.

     The undersigned, a duly authorized officer of Beneficiary under the Letter
of Credit, certifies and represents that the Beneficiary is drawing on this
Letter of Credit in accordance with the provisions of the Deed of Lease dated
September __, 1997, by and between the Beneficiary and Advanced Switching
Communications, Inc.

     The undersigned has executed this statement as of the __ day of _______,
____.

WITNESS or ATTEST:    MET LIFE INTERNATIONAL REAL ESTATE EQUITY
                      SHARES, INC.,
                       a Delaware corporation

__________________    By:                           [SEAL]
                          __________________________
                          Name:
                          Title:

                                     E-2<PAGE>   1

                                                                    EXHIBIT 10.5

                                 LOAN AGREEMENT

       THIS LOAN AGREEMENT (this "Agreement") is dated as of August 15, 2000,
between VALORINVEST, LTD. ("Lender") and HEALTHBRIDGE, INC., a Texas corporation
("Borrower").

       WHEREAS, Borrower wants to obtain financing for use as working capital.

       NOW THEREFORE, for and in consideration of the premises, and other good
and valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, the parties agree as follows:

       1.     LOAN. Lender will provide the Borrower with a loan in the amount
of up to US$500,000 (the "Loan"). The Loan shall be evidenced by Borrower's
promissory note substantially in the form attached hereto as Exhibit A (the
"Note"). Upon receiving a properly executed original of this Note, Lender agrees
to make available the proceeds of the loan. Advances shall be made available in
$50,000 increments upon ten (10) business days written notice of demand by
Borrower; provided, however, that Lender is not required to advance more than
$50,000 in any thirty (30) day period. Advances are limited in the aggregate to
the stated principal amount of this Note; this is not a revolving line of
credit.

       2.     INTEREST. The Loan shall bear interest at a rate of seven and one
half percent (7.5%) per annum.

       3.     REPAYMENT OF LOAN. The outstanding principal balance of the Loan
and accrued and unpaid interest thereon shall be due and payable upon the
earlier of (a) September 1, 2001; or (b) within ten (10) days of the
consummation of any equity or debt financings providing Borrower with gross
proceeds of at least US$2,000,000, in the aggregate.

       4.     ISSUANCE OF WARRANTS. Borrower shall issue warrants for its common
stock (the "Warrants", and each individually, a "Warrant") for the benefit of
Lender, in substantially the same form as that attached hereto as Exhibit B.
Borrower and Lender agree that the exercise price per share of common stock
represented by the Warrant shall be $0.50 per share. Upon each advance under
Section 1 of this Agreement Borrower shall issue a Warrant for common stock
equal to the pro rata portion of the advance as a percentage of the principal
amount of the Loan, provided that any fractional percentages shall be rounded up
to the next whole percent until Warrants representing an aggregate of 200,000
shares of common stock are issued. For example, if Lender makes an advance of
$50,000, Borrower shall simultaneously with such advance issue Lender a Warrant
to purchase 20,000 shares of its common stock.

       5.     REPRESENTATIONS, WARRANTIES, AND COVENANTS OF BORROWER. Borrower
represents, warrants and covenants to Lender as follows:

       (a)  Corporate Organization and Good Standing. Borrower is a corporation
       duly organized, validly existing and in good standing under the laws of
       its jurisdiction, with

<PAGE>   2

       all requisite corporate power and authority to own, operate and lease its
       properties and to carry on its business as it is now being conducted.
       Borrower is qualified and in good standing to do business in all
       jurisdictions where its business or ownership or leasing of property or
       assets requires such qualification.

       (b)  Authority. Borrower has all requisite corporate power and authority
       to execute and deliver this Agreement and to perform its obligations
       hereunder and to consummate the transactions contemplated hereby.

       6.     NOTICE. All notices, requests, demands and other communications
required or permitted hereunder must be in writing and shall be effective (a)
five days after being mailed by first class and certified or registered mail,
return receipt requested, with proper postage prepaid, or (b) two (2) business
days after being delivered to an established over-night delivery service, with
costs for "next day" delivery prepaid, addressed in either case to the following
addresses (or in either case to such other address as such party may from time
to time designate to the other by like written notice):

              To the Borrower:          Healthbridge, Inc.
                                        Attention: Ms. Nora Coccaro
                                        1177 West Hastings Street
                                        Suite 1818
                                        Vancouver, BC
                                        Canada V6E2K3
                                        Tel: (604) 602-1717
                                        Fax: (604) 408-1739

              To the Lender:            ValorInvest Ltd.
                                        Attention: Mr. Pierre Besuchet
                                        29 Quai des Bergues
                                        1201 Geneva
                                        Switzerland
                                        Tel: 41-22-732-53-55
                                        Fax: 41-22-732-56-95

       7.     MISCELLANEOUS.

              (a)    Successors and Assigns. This Agreement shall apply to and
bind Borrower and Lender and each of their respective successors and permitted
assigns.

              (b)    Governing Law and Choice of Forum. The validity and
construction of this Note and all matters pertaining thereto are to be
determined and construed according to the laws of the State of Texas, excluding
its conflicts of law principles.

              (c)    Severability. In the event any provision (or any part of
any provision) contained in this Agreement shall for any reason be finally held
by a court of competent jurisdiction to be invalid, illegal or unenforceable in
any respect, such invalidity, illegality or unenforceability shall not affect
any other provision (or remaining part of the affected

                                       2
<PAGE>   3

provision) of this Agreement; but this Agreement shall be construed as if such
invalid, illegal or unenforceable provision (or part thereof) had never been
contained herein, but only to the extent it is invalid, illegal or
unenforceable.

              (d)    Captions and Section Headings. Captions and section
headings used herein are for convenience only and are not a part of this
Agreement and will not be used in construing it.

              (e)    Fax Execution. This Agreement may be executed by delivery
of executed signature pages by fax and such fax execution will be effective for
all purposes.

              IN WITNESS WHEREOF, the parties have duly executed this Agreement
as of the date first set forth above.

                                                     VALORINVEST LTD.

                                                     BY: /S/ PIERRE BESUCHET
                                                         -------------------
                                                         Pierre Besuchet
                                                         Director and Secretary

                                                     HEALTHBRIDGE, INC.

                                                     By: /S/ NORA COCCARO
                                                         ----------------
                                                         Nora Coccaro
                                                         President

                                       3

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00014-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00014-of-00352.parquet"}]]