<PAGE>   1

                                  DEED OF LEASE


         THIS DEED OF LEASE (this "Lease") is made as of the 8th day of May,
1998 (the "Date of Lease"), by FCP-DULLES BUSINESS PARK I, L.C., a Virginia
limited liability company ("Landlord"), and PINNACLE REAL ESTATE TAX SERVICES,
INC., a Delaware corporation ("Tenant").

         Landlord and Tenant, intending legally to be bound, hereby covenant and
agree as set forth below.

                                    ARTICLE I
                             BASIC LEASE PROVISIONS

         The following terms, when used herein, shall have the meanings set
forth below.

         1.1 Premises. For purposes of this Lease, the gross rentable square
footage of the Premises shall be deemed to be 33,363 square feet, known as of
the Date of Lease as Suite 200 and located in the Building as outlined on
Exhibit A-1 attached hereto and made a part hereof. The premises are measured in
accordance with the Greater Washington Commercial Association of Realtors
standard method of measurement (GWCAR), based on construction plans for the
Building, and the exterior walls of the Building, which have been constructed as
of the date hereof, and the parties hereby stipulate to such measurement.

         1.2 Building. The building containing approximately 58,393 gross
rentable square feet shown on Exhibit A-2 attached hereto and made a part
hereof, and all alterations, additions, improvements, restorations or
replacements now or hereafter made thereto, with an address of:

                             14026 Thunderbolt Place
                            Chantilly, Virginia 22021


         1.3 Term. Ten (10) years.

         1.4 Commencement Date. October 1, 1998, subject to adjustment as set
forth in Article 4.

         1.5 Expiration Date. September 30, 2008, subject to adjustment as set
forth in Article 4.

         1.6 Base Rent. $13.00 for each rentable square foot of the Premises for
the first Lease Year which is equal to a total of $ 433,719.00 for the first
Lease Year payable in equal monthly installments of $36,143.25. The Base Rent
shall be increased annually by an amount equal to three percent (3%) of the
previous Lease Year's Base Rent commencing the second Lease Year in accordance
with the following schedule:
<TABLE>
<CAPTION>

            Lease Year       Annual Base Rent          Monthly Installment
            ----------       ----------------          -------------------
<S>                          <C>                       <C>          
                 1           $   433,719.00              $   36,143.25
                 2           $   446,730.60              $   37,227.55
                 3           $   460,132.44              $   38,344.37
                 4           $   473,936.52              $   39,494.71
                 5           $   488,154.60              $   40,679.55
                 6           $   502,799.16              $   41,899.93
                 7           $   517,883.16              $   43,156.93
                 8           $   533,419.68              $   44,451.64
                 9           $   549,422.28              $   45,785.19
                10           $   565,904.88              $   47,158.74
</TABLE>

         1.7 Security Deposit. Not Applicable.

                                       1

<PAGE>   2


         1.8 Tenant's Proportionate Share of Common Area Expenses. 57.14% of the
Common Area Expenses allocable to the Building which is based upon the Premises
containing 33,363 gross rentable square feet of the Building containing a total
of 58,393 gross rentable square feet.

         1.9 Tenant's Proportionate Share of Real Estate Taxes. 57.14% of the
Real Estate Taxes allocable to the Building which is based upon the Premises
containing 33,363 gross rentable square feet of the Building containing a total
of 58,393 gross rentable square feet.

         1.10 Parking Space Allocation. 120 spaces, which shall be without
charge, in unreserved, non-exclusive parking spaces available in the Parking
Facilities, except for six (6) reserved parking spaces which shall be located in
proximity to the main entrance of the Premises, as shown on Exhibit A-2.

         1.11 Permitted Use. General office and administrative use. No other
purpose.

         1.12 Tenant's Trade Name. Pinnacle Real Estate Tax Services, Inc.

         1.13 Broker(s). Landlord's: The Carey Winston Company
                         Tenant's:   CB Commercial Real Estate in conjunction 
                                     with Cushman Realty Corporation

         1.14 Landlord's Address.    FCP-Dulles Business Park I, L.C.
                                     c/o Crimson Partners, L.C.
                                     455 Spring Park Place
                                     Suite 100
                                     Herndon, Virginia 22070
                                     Attn:  R. Kevin Dougherty

                  With a copy to:    Mark S. Tenenbaum, Esq.
                                     Tenenbaum & Saas, P.C.
                                     4330 East-West Highway
                                     Suite 1150
                                     Bethesda, MD 20814

         1.15 Tenant's Address.

                  Before occupancy:  Pinnacle Real Estate Tax Services, Inc.
                                     395 Oyster Point, Suite 500
                                     South San Francisco, CA 94080
                                     Attn:  Donald S. Grant, V.P. Facilities

                  With a copy to:    Pinnacle Real Estate Tax Services, Inc.
                                     395 Oyster Point, Suite 500
                                     South San Francisco, CA 94080
                                     Attn:  Robert Barbarowicz, General Counsel

                  After Occupancy:   Pinnacle Real Estate Tax Services, Inc.
                                     14026 Thunderbolt Place
                                     Chantilly, Virginia 22021
                                     Attn: Gunnar Bergstrom, 
                                           Executive Vice President

                  With a copy to:    Pinnacle Real Estate Tax Services, Inc.
                                     395 Oyster Point, Suite 500
                                     South San Francisco, CA 94080
                                     Attn: Donald S. Grant, V.P. Facilities

                                       2

<PAGE>   3



                  With a copy to:    Pinnacle Real Estate Tax Services, Inc.
                                     395 Oyster Point, Suite 500
                                     South San Francisco, CA 94080
                                     Attn: Robert Barbarowicz, General Counsel

         1.16 Guarantor and Guarantor's Address:

                                     National Insurance Group
                                     395 Oyster Point, Suite 500
                                     South San Francisco, CA 94080

                                    ARTICLE 2
                                   DEFINITIONS

         The following terms, when used herein, shall have the meanings set
forth below.

         2.1 Additional Rent. As defined in Section 5.3.

         2.2 Agents. Officers, partners, directors, employees, agents,
licensees, customers and invitees.

         2.3 Alterations. Alterations, decorations, additions or improvements of
any kind or nature to the Premises or the Building, whether structural or
non-structural, interior, exterior or otherwise.

         2.4 Calendar Year. A period of twelve (12) months commencing on each
January 1 during the Term, except that the first Calendar Year shall be that
period from and including the Commencement Date through December 31 of that same
year, and the last Calendar Year shall be that period from and including the
last January 1 of the Term through the earlier of the Expiration Date or date of
Lease termination.

         2.5 Common Area. All areas, improvements, facilities and equipment from
time to time designated by Landlord for the common use or benefit of Tenant,
other tenants of the Building and their Agents, including, without limitation,
roadways, entrances and exits, landscaped areas, open areas, exterior lighting,
service drives, loading areas, pedestrian walkways, sidewalks, stairs, ramps,
maintenance and utility rooms and closets, exterior utility lines, common window
areas, common trash areas and Parking Facilities.

         2.6 Common Area Expenses. As defined in Section 7.2.

         2.7 Dulles Business Park: The planned office development described in
that certain Declaration dated October 25, 1984 and recorded in the Clerk's
Office of the Circuit Court for Fairfax County, Virginia at Deed Book 6046 at
Page 218, and re-recorded in Deed Book 6877 at page 1528, as amended by
instruments recorded in Deed Book 6712 at page 780, Deed Book 7028 at Page 1392
and Deed Book 7539 at Page 193 among the aforesaid land records, as the same may
be improved, modified, reconfigured, expanded and/or contracted from time to
time in the discretion of Landlord and its affiliates.

         2.8 Event of Default. As defined in Article 22.

         2.9 Herein, hereafter, hereunder and hereof. Under this Lease,
including, without limitation, all Exhibits and any Riders.

         2.10 Including and/or includes. Including, but not limited to, and/or
includes, without limitation. The term "including" and like terms used herein to
identify particular items as being related to (or examples of) a descriptive
term, phrase or provision shall, unless where expressly indicated to the
contrary, be viewed as non-

                                       3


<PAGE>   4

exclusive, and the identification of particular items, or use of such examples,
shall not limit any other item or example which fits within the particular
descriptive term, phrase or provision.

         2.11 Interest Rate. Per annum interest rate listed as the base rate on
corporate loans at large U.S. money center commercial banks as published from
time to time under "Money Rates" in the Wall Street Journal plus two percent (2
%), but in no event greater than the maximum rate permitted by law. In the event
the Wall Street Journal ceases to publish such rates, Landlord shall choose at
Landlord's sole discretion a similar publication which publishes such rates.

         2.12 Land. The piece or parcel of land described in Exhibit A-2 and all
rights, easements and appurtenances thereunto belonging or pertaining, or such
portion thereof as shall be allocated by Landlord to the Building.

         2.13 Lease Year. Each consecutive twelve (12) month period elapsing
after (i) the Commencement Date if the Commencement Date occurs on the first day
of a month, or (ii) the first day of the month following the Commencement Date
if the Commencement Date does not occur on the first day of a month.

         2.14 Mortgage. Any mortgage, deed of trust, security interest or title
retention interest affecting the Building or the Land.

         2.15 Mortgagee. The holder of any note or obligation secured by a
mortgage, deed of trust, security interest or title retention interest affecting
the Building or the Land, including, without limitation, lessors under ground
leases, sale-leasebacks and lease-leasebacks.

         2.16 Parking Facilities. All parking areas now or hereafter made
available by Landlord for use by tenants of the Building, including, without
limitation, open-air parking, parking decks and parking areas under or within
the Building, whether reserved, non-exclusive or otherwise.

         2.17 Project. That portion of the Dulles Business Park office
development which is owned from time to time by Landlord and/or its affiliates,
or any portion thereof which was at one time owned by Landlord to the extent the
same, after the transfer thereof by Landlord to a third party, is then
maintained in common with any buildings still owned by Landlord, whether
pursuant to reciprocal maintenance, easement or other agreements, or otherwise.

         2.18 Real Estate Taxes. As defined in Article 8.

         2.19 Rent. Base Rent and Additional Rent.

         2.20 Rules and Regulations. The rules and regulations set forth in
Exhibit C attached hereto and made a part hereof, as the same may be amended or
supplemented from time to time.

         2.21 Substantial Completion. As defined in the Work Agreement attached
hereto and made a part hereof as Exhibit B.

         2.22 Substantial Part. More than fifty percent (50%) of the rentable
square feet of the Premises or the Building, as the case may be.

         2.23 Work Agreement. As set forth in Exhibit B attached hereto and made
a part of.


                                       4
<PAGE>   5




                                    ARTICLE 3
                                  THE PREMISES

         3.1 Lease of Premises. In consideration of the agreements contained
herein, Landlord hereby leases the Premises to Tenant, and Tenant hereby leases
the Premises from Landlord, for the Term and upon the terms and conditions
hereinafter provided. As an appurtenance to the Premises, Tenant shall have the
non-exclusive right, together with other tenants of the Building and their
Agents, to use the Common Area. Landlord shall retain absolute dominion and
control over the Common Area and shall operate and maintain the Common Area in
such manner as Landlord, in its sole but reasonable judgment shall determine
consistent with standards applicable for a first class office/flex building;
provided, however such exclusive right shall not operate to prohibit Tenant from
its use of the Premises for the Permitted Use. Landlord expressly reserves the
right permanently to change, modify or eliminate, or temporarily to close, any
portion of the Common Area. The Premises are leased subject to, and Tenant
agrees not to violate, all present and future covenants, conditions and
restrictions of record which affect the Land.

         3.2 Landlord's Reservations. In addition to the other rights of
Landlord under this Lease, Landlord reserves the right (i) to change the name of
the Building, (ii) to install, erect, use, maintain and repair mains, pipes,
conduits and other such facilities to serve the Building's tenants in and
through the Premises, (iii) to grant to anyone the exclusive right to conduct
any particular business or undertaking in the Building, (iv) to control the use
of the roof and exterior walls of the Building for any purpose, and (v) to
modify the size and configuration of the Common Area, including the construction
of temporary or permanent structures or improvements therein. 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 Tenant's use or occupancy of the Premises, subject to
Article 12 of this Lease.


                                    ARTICLE 4
                                      TERM

         The Term shall commence on the Commencement Date and expire at midnight
on the Expiration Date. Except as provided in Exhibit B, if Substantial
Completion of the Premises has not occurred on the date set forth in Article I
as the Commencement Date (other than as a result of Tenant Delays), or if Tenant
uses or accepts possession of the Premises before the date set forth in Article
I as the Commencement Date, then the Commencement Date shall be the earlier of
(i) the first Monday occurring after the date of Substantial Completion or (ii)
the date upon which Tenant commences business operations within the Premises
(exclusive of Tenant's Move-In and Early Work, as defined and described in
Section 6.5 of Exhibit B). In such event, the Commencement Date shall be
adjusted accordingly so that the period of the Term is not changed. If requested
by Landlord, Tenant shall within fifteen (15) days of such request sign a
declaration acknowledging the Commencement Date and the Expiration Date in the
form attached hereto and made a part hereof as Exhibit D .

                                    ARTICLE 5
                                      RENT

         5.1 Base Rent. Tenant shall pay to Landlord the Base Rent as specified
in Section 1.6.

         5.2 Payment of Base Rent. Base Rent for each Lease Year shall be
payable in equal monthly installments, in advance, without demand, notice,
deduction, offset or counterclaim, on or before the first day of each and every
calendar month during the Term; provided, however, that the installment of the
Base Rent payable for the first full calendar month of the Term (and, if the
Commencement Date occurs on a date other than on the first day of a calendar
mouth, Base Rent prorated from such date until the first day of the following
month) shall be due and payable on the full execution and delivery of this
Lease. Tenant shall pay the Base Rent and all 


                                       5


<PAGE>   6

Additional Rent, by good check, made payable to Landlord or in lawful currency
of the United States of America, to Landlord at 455 Spring Park Place, Suite
100, Herndon, Virginia 22070 or to such other address or in such other manner as
Landlord from time to time specifies by written notice to Tenant. Any payment
made by Tenant to Landlord on account of Base Rent may be credited by Landlord
to the payment of any late charges then due and payable and to any Base Rent or
Additional Rent then past due before being credited to Base Rent currently due.

         5.3 Additional Rent. All sums payable by Tenant under this Lease, other
than Base Rent, shall be deemed "Additional Rent", and, unless otherwise set
forth herein, shall be payable in the same manner as set forth above for Base
Rent.

         5.4 Acceptance of Rent. If Landlord shall direct Tenant to pay Base
Rent or Additional Rent to a "lockbox" or other depository whereby checks in
payment of Base Rent or Additional Rent (or both, as the case may be) are
initially cashed or deposited by a person or entity other than Landlord (albeit
on Landlord's authority), Tenant agrees to make such payments in a timely
fashion in accordance with such direction from Landlord.


                                    ARTICLE 6
                             [INTENTIONALLY DELETED]

                                    ARTICLE 7
                              COMMON AREA EXPENSES

         7.1 Tenant's Proportionate Share. Tenant shall pay to Landlord
throughout the Term, as Additional Rent, Tenant's Proportionate Share of the
Common Area Expenses. In the event that the Commencement Date or the Expiration
Date are other than the first day of a Calendar Year then Tenant's Proportionate
Share of the Common Area Expenses shall be adjusted to reflect the actual period
of occupancy during the Calendar Year.

         7.2 Common Area Expenses Defined. As used herein, the term "Common Area
Expenses" shall mean all expenses and costs of every kind and nature which
Landlord incurs because of or in connection with the ownership, maintenance,
management and operation of the Building (which expressly includes the Land, the
Building and the Common Area). To the extent the Building is part of, or
continues to maintained in conjunction with, the Project, Landlord shall have
the right (but not the obligation) to provide certain services contemplated
herein to the Building in conjunction with one or more buildings in the Project,
in which event an appropriate portion of the expenses associated therewith
(based on the relative square footage of the Buildings, or, if allocation based
solely on square footage would be inequitable, based on the relative benefit to
each such building from such expense) shall be allocated by Landlord to the
Building as Common Area Expenses hereunder. By way of example, and not of
limitation, snow removal costs for the Project shall be allocated on an
appropriate basis between all tenantable buildings in the Project which receive
the benefit of such snow removal services under a single snow removal contract.
Common Area Expenses shall include, without limitation, all reasonable costs,
expenses and disbursements incurred or made in connection with the following:

         (i) Wages and salaries of all employees, whether employed by Landlord
or the Building's management company, engaged in the operation and maintenance
or security of the Building and all costs related to or associated with such
employees or the carrying out of their duties, including uniforms and their
cleaning, taxes, auto allowances and insurance and benefits (including, without
limitation, contributions to pension and/or profit sharing plans and vacation or
other paid absences);

         (ii) All supplies and materials, including janitorial and lighting
supplies, used directly in the operation and maintenance of the Building;
 

                                       6

<PAGE>   7

         (iii) All utilities, including, without limitation, electricity,
telephone (including, without limitation, all costs and expenses of telephone
service for the sprinkler alarm system, if any), water, sewer, power, gas,
heating, lighting and air conditioning for the Building, except to the extent
such utilities are charged directly to or paid by, a tenant of the building;

         (iv) All insurance purchased by Landlord or the Building's management
company relating to the Building and any equipment or other property contained
therein or located thereon including, without limitation, casualty, liability,
rental loss, sprinkler and water damage insurance;

         (v) All repairs to the Building (excluding repairs paid for by the
proceeds of insurance irrespective of any deductibles applicable thereto, or by
Tenant or other third parties other than as a part of the Common Area Expenses),
including interior and exterior, and regardless of whether foreseen or
unforeseen, except as provided in Section 12.1, below;

         (vi) All maintenance of the Building, including, without limitation,
painting, ice and snow removal, landscaping, groundskeeping and the patching,
painting and resurfacing of roads, driveways and parking lots;

         (vii) All maintenance, operation and service agreements for the
Building, and any equipment related thereto, including, without limitation,
service and/or maintenance agreements for the sprinkler system in the Building,
if any (excluding those paid for by Tenant or any other third parties other than
as a part of Common Area Expenses);

         (viii) A management fee payable to Landlord or the company or companies
managing the Building, if any, not to exceed market rates for the management of
similar buildings to the Building in the vicinity of the Building in Fairfax
County Virginia;

         (ix) Accounting and legal fees incurred in connection with the
operation and maintenance of the Building or related thereto;

         (x) Any additional services not provided to the Building at the
Commencement Date but thereafter provided by Landlord as Landlord shall deem
necessary or desirable in connection with the management or operation of the
Building, the Land and the Common Area;

         (xi) All private assessments, whether general, special or otherwise,
levied against Landlord or the Building pursuant to any declaration or other
instrument affecting the Building or any part or component thereof, including
without limitation that certain Declaration for the Dulles Business Park as the
same may be amended from time to time in accordance with the terms thereof;

         (xii) any capital expenditures (1) incurred for the intended purpose of
reducing Common Area Expenses or utility costs by an amount which, over the
useful life of the item to which such capital expenditure relates, exceeds the
cost of the capital expenditure incurred to produce such savings, or (2)
incurred to comply with change in any governmental laws, orders, regulations or
other requirements (e.g., a code-mandated life safety system) to the extent such
change is enacted or effected after the Date of Lease (including any such change
in laws or in the interpretation thereof which results in any loss of
"grandfathering" or other exception to compliance to which Landlord is entitled
under existing laws or regulations as of the Date of Lease); provided that all
capital expenditures described above shall be amortized on a monthly payment
basis over the actual useful life of the item in question, as reasonably
determined by Landlord in accordance with generally accepted accounting
principles, based on the type of the equipment replaced, together with interest
at the Interest Rate (or such higher interest rate as may have been paid by
Landlord on funds borrowed for the purposes of incurring such capital
expenditures), and only the total monthly payments of principal and interest
coming due in each applicable calendar year during the Term, as determined under
such amortization schedule, shall be recoverable by Landlord under this Section
in any such calendar year, and in the case of clause (1), above, shall not
exceed 

                                       7



<PAGE>   8

the amount of the reduction in Common Area Expenses realized or derived as a
result of such expenditure in any year during which such expenditure is being
recovered under this subparagraph;


         (xiii) Subject to Section 7.3, below, all other expenses and costs
reasonably necessary for operating and maintaining the Building.

         7.3 Exclusions from Common Area Expenses. Notwithstanding Section 7.2
to the contrary, the following costs and expenses shall be excluded from Common
Area Costs:

         (i) Costs and expenses associated with the operation of the business of
the ownership or entity which constitutes "Landlord" as distinguished from the
costs of building operations, including but not limited to partnership
accounting and legal matters, costs of defending any lawsuits with any mortgagee
(except to the extent the actions of Tenant may be in issue), costs of selling,
syndicating, financing, mortgaging or hypothecating any of Landlord's interest
in the Building, costs of disputes between Landlord and its property manager or
between Landlord and its employees (if any) who are not engaged in Building
operations, or outside fees paid in connection with disputes with other tenants
(except to the extent such fees are paid in connection with the enforcement of
lease covenants which will inure to the benefit of other tenants of the
Property);

         (ii) Costs incurred in connection with the original design and
construction of the Building;

         (iii) Costs of alterations or improvements of the Premises or the
premises of other tenants, except to the extent required by applicable law or
reasonably incurred to reduce Common Area Expenses;

         (iv) Depreciation, interest and principal payments on mortgages and
other debt costs, if any, (exclusive of any portions paid for real estate taxes,
insurance or other expenses which are properly included in Common Area
Expenses), except as expressly contemplated in Section 7.2(xii), above, with
respect to the amortization of and the interest factor attributable to the cost
of certain capital expenses permitted to be included as Common Area Expenses;

         (v) Costs of correcting defects in the design or construction of the
Building or the materials used in the construction of the Building or the
equipment or appurtenances thereto;

         (vi) Additional incremental expenses directly resulting from the
negligence of Landlord or Landlord's Agents;

         (vii) Legal fees, space planners' fees, real estate brokers' leasing
commissions and advertising expenses incurred in connection with the original
development or original leasing of the Building or future leasing of the
Building;

         (viii) The portion of any cost or expense which is reimbursed to
Landlord by Landlord's insurance carrier or any tenant's insurance carrier;

         (ix) Any bad debt loss, rent loss, or reserves for bad debts or rent
loss;

         (x) The expense of providing a level of service to any other tenant of
the Building which materially exceeds the level of service provided to Tenant
without additional charge, to the extent of such excess;

         (xi) The portion of any wages of any employee which is attributable to
hours not devoted to the Property;

         (xii) Fines, penalties and (except as otherwise permitted herein)
interest;


                                       8
<PAGE>   9

         (xiii) Amounts paid as ground rental by Landlord (exclusive of any
portions paid for real estate taxes, insurance or other expenses which are
properly included in Common Area Expenses);

         (xiv) Any operating costs to provide services which are solely for the
benefit of retail tenants;

         (xv) Any recalculation of, or additional, Common Area Expenses actually
incurred more than one year prior to the year in which Landlord proposes that
such costs be included, except as permitted pursuant to Section 7.2 (xii),
above;

         (xvi) Capital expenditures, except as provided for in Section 7.2(xii),
above;

         (xvii) Costs incurred by Landlord with respect to goods and services
(including utilities sold and supplied to tenants and occupants of the Building)
to the extent that Landlord is entitled to reimbursement for such costs (other
than through reimbursements of tenants' share of Common Area Expenses;

         (xviii) Costs, including permit, license and inspection costs, incurred
with respect to the installation of tenant improvements made for new tenants in
the Building, or incurred in renovating, decorating, or redecorating vacant
space for tenants or other occupants of the Building;

         (xix) The portion of any fee (including management fees), charge or
expense which exceeds by more than a de minimis amount the market rates for
goods and services provided in exchange therefor, for properties similar to and
located in the same general vicinity as the Property (including overhead, profit
increment paid to Landlord or to subsidiaries or affiliates of Landlord for
services in the Building, to the extent the same exceeds by more than a de
minimis amount the costs of such services rendered by reputable unaffiliated
third parties supplying such services or items to properties similar to and
located in the same general vicinity as the Property );

         (xx) Any compensation paid to clerks, attendants or other persons in
commercial concessions operated by Landlord in the Building;

         (xxi) Rental expenses incurred to lease air conditioning systems,
elevators or other equipment ordinarily considered to be of a capital nature
which, if purchased rather than leased, would not be included in Common Area
Expenses pursuant to Paragraph 7.2(xii) and 7.3(xvi), above;

         (xxii) Electric power costs for which any Tenant directly contracts
with the local public service company; and

         (xxiii) Any mark-up on utilities provided by Landlord.

It is understood that Common Area Expenses will be reduced by all trade and
quantity discounts received by Landlord or Landlord's managing agent in the
purchase of goods, utilities or services in connection with the operation of the
Building. In calculating Common Area Expenses hereunder, no individual
expenditure will be charged more than once. Landlord agrees to use commercially
reasonable efforts to effect an equitable apportionment of bills for services
rendered to the Building and any other property owned by Landlord. Landlord
agrees to keep books and records showing Common Area expenses in accordance with
a system of accounts and accounting practices which are consistently applied.


         7.4 Estimated Payments. Landlord shall submit to Tenant, before the
beginning of each Calendar Year, a statement of Landlord's estimate of the
Common Area Expenses payable by Tenant during such Calendar Year. In addition to
the Base Rent, Tenant shall pay to Landlord on or before the first day of each
month during such Calendar Year an amount equal to one-twelfth (1/12) the
estimated Common Area Expenses payable by Tenant for such Calendar Year as set
forth in Landlord's statement. If Landlord fails to give Tenant notice of its


                                       9


<PAGE>   10

estimated payments due under this Section for any Calendar Year, then Tenant
shall continue making monthly estimated payments in accordance with the estimate
for the previous Calendar Year until a new estimate is provided. If Landlord
determines that, because of unexpected increases in Common Area Expenses or
other reasons, Landlord's estimate of the Common Area Expenses was too low, then
Landlord shall have the right to give a new statement of the estimated Common
Area Expenses due from Tenant for such Calendar Year or the balance thereof and
to bill Tenant for any deficiency which may have accrued during such Calendar
Year, and Tenant shall thereafter pay monthly estimated payments based on such
new statement.

         7.5 Actual Common Area Expenses. Within one hundred twenty (120) days
after the end of each Calendar Year, Landlord shall submit a statement to Tenant
showing the actual Common Area Expenses for such Calendar Year and Tenant's
Proportionate Share of the amount of such Common Area Expenses. If for any
Calendar Year, Tenant's estimated monthly payments exceed Tenant's Proportionate
Share of the actual Common Area Expenses for such Calendar Year, then Landlord
shall give Tenant a credit in the amount of the overpayment toward Tenant's next
monthly payments of estimated Common Area Expenses. If for any Calendar Year
Tenant's estimated monthly payments are less than Tenant's Proportionate Share
of the actual Common Area Expenses for such Calendar Year, then Tenant shall pay
the total amount of such deficiency to Landlord within thirty (30) days after
receipt of the statement from Landlord. Landlord's and Tenant's obligations with
respect to any overpayment or underpayment of Common Area Expenses shall survive
the expiration or termination of this Lease.

         7.6 Tenant's Right to Audit. Tenant and its authorized representative
shall, upon reasonable prior written notice, have the right at its sole expense
(except as provided below) to examine, inspect and copy the records of Landlord
regarding each statement of Common Area Expenses and Taxes within sixty (60)
days after receipt of such statement, in order to determine whether to proceed
with an audit thereof. In the event Tenant shall dispute the amount set forth in
Landlord's statement of actual Common Area Expenses, Tenant shall have the
right, not later than one hundred twenty (120) days following receipt of such
statement, to cause Landlord's books and records with respect to the preceding
Calendar Year to be audited by an independent Certified Public Accountant
mutually acceptable to Landlord and Tenant. Such audit shall occur upon not less
than five (5) days prior written notice to Landlord, at Landlord's place of
business or the actual location of Landlord's books and records if different
from Landlord's place of business, during Landlord's normal business hours. The
amounts payable under this Section by Landlord to Tenant or by Tenant to
Landlord, as the case may be, shall be appropriately adjusted on the basis of
such audit. If such audit discloses a liability for further refund by Landlord
to Tenant in excess of five percent (5%) of the payments previously made by
Tenant for such Calendar Year, the reasonable cost of such audit shall be borne
by Landlord and shall not be considered as a Common Area Expense for purposes of
this Lease; otherwise, the cost of such audit shall be borne by Tenant. If
Tenant shall not request an audit in accordance with the provisions of this
Section within one hundred twenty (120) days after receipt of Landlord's
statement of actual Common Area Expenses, such statement shall be conclusively
binding upon Landlord and Tenant.

                                    ARTICLE 8
                                      TAXES

         8.1 Generally. Tenant shall pay to Landlord throughout the Term, as
Additional Rent, Tenant's Proportionate Share of Real Estate Taxes, In the event
the Commencement Date or the Expiration Date are other than the first (1st) day
of a Calendar Year, the Tenant's Proportionate Share of the Real Estate Taxes
shall be adjusted to reflect the actual period of occupancy during the Calendar
Year. "Real Estate Taxes" shall mean all taxes and assessments, including but
not limited to, general or special, ordinary or extraordinary, foreseen or
unforeseen, assessed, levied or imposed by any governmental authority upon the
Building and the Land and upon the fixtures, machinery, equipment or systems in,
upon or used in connection with any of the foregoing, and the rental, revenue or
receipts derived therefrom, under the current or any future taxation or
assessment system or modification of, supplement to, or substitute for such
system. Real Estate Taxes also shall include special assessments which are in
the nature of or in substitution for real estate taxes, including, without
limitation, road 


                                       10


<PAGE>   11

improvement assessments, special tax district assessments, special use area
assessments and school district assessments, provided that Taxes shall not
include any special assessments for off-site improvements hereafter incurred by
Landlord if such assessments are negotiated by Landlord in exchange for
development rights or zoning or other governmental approvals for the benefit of
properties other than the Property, or which do not directly benefit the
Property (it being agreed, however, that assessments made by any special tax
district, special use area and school district, to the extent such assessment
district was created with respect to multiple properties that include properties
not owned by Landlord, as opposed to being created by Landlord in order to
indirectly fund improvements or zoning rights that benefit properties owned by
Landlord other than the Property, such as assessments made as part of the Route
28 taxing district, shall be included within the definition of Real Estate
Taxes). If at any time the method of taxation prevailing at the Date of Lease
shall be altered so that in lieu of, as a substitute for or in addition to the
whole or any part of the taxes now levied or assessed, there shall be levied or
assessed a tax of whatever nature, then the same shall be included as Real
Estate Taxes hereunder. Further, for the purposes of this Article, Real Estate
Taxes shall include the reasonable expenses (including, without limitation,
attorneys' fees) incurred by Landlord in challenging or obtaining or attempting
to obtain a reduction of such Real Estate Taxes, regardless of the outcome of
such challenge. Notwithstanding the foregoing, Landlord shall have no obligation
to challenge Real Estate Taxes. If, as a result of any such challenge, a tax
refund is made to Landlord, then the amount of such refund less the expenses of
the challenge shall be deducted from Real Estate Taxes due in the Lease Year
such refund is received. Landlord shall charge Tenant for its Proportionate
Share of Real Estate Taxes in accordance with the procedures established under
Sections 7.4 and 7.5 for payment of Common Area Expenses.

         8.2 Cap on Taxes and Common Expenses for Calendar Year 1998.
Notwithstanding Sections 7.5 and 8.1, above, to the contrary, the aggregate
amount of Taxes and Common Area Expenses charged by Landlord to Tenant during
the first full Lease Year shall not exceed an annualized amount equal to
$70,062.30 (which is the product obtained by multiplying $2.10 per annum times
the 33,363 square foot rentable area of the Premises). The foregoing cap shall
not be effective after the first Lease Year.

                                    ARTICLE 9
                                     PARKING

         9.1 Parking Spaces. During the Term, Tenant shall have the right to use
the Parking Space Allocation for its employees, agents, business guests and
invitees. Tenant's Parking Space Allocation shall consist of unreserved and
non-exclusive parking spaces available in the Parking Facilities, except for six
(6) reserved parking spaces which shall be located in proximity to the main
entrance of the Premises, as shown on Exhibit A-2. Tenant shall not overburden
the Parking Facilities, and any usage in excess of the Parking Space Allocation
may, at Landlord's election, be deemed to overburden the Parking Facilities.

         9.2 Changes to Parking Facilities. Landlord shall have the right, from
time to time, without Tenant's consent, to change, alter, add to, temporarily
close or otherwise affect the Parking Facilities in such manner as Landlord, in
its sole discretion, deems appropriate including, without limitation, the right
to designate reserved spaces available only for use by one or more tenants
(however, in such event, those parking spaces shall still be deemed Common Area
for the Purpose of the definition of Common Area Expenses), provided that,
except in emergency situations or situations beyond Landlord's control, Landlord
shall provide alternative Parking Facilities.

                                   ARTICLE 10
                                       USE

         Tenant shall occupy the Premises solely for the Permitted Use. The
Premises shall not be used for any other purpose without the prior written
consent of Landlord. Tenant shall comply, at Tenant's expense, with (i) all
present and future laws, ordinances, regulations and orders of the United States
of America, the 

                                       11


<PAGE>   12

Commonwealth of Virginia and any other public or quasi-public federal, state or
local authority having jurisdiction over the Premises, and (ii) any reasonable
requests of Mortgagee or any insurance company providing coverage with respect
to the Premises. Tenant shall not use or occupy the Premises in any manner that
is unlawful or dangerous or that shall constitute waste, unreasonable annoyance
or a nuisance to Landlord or the other tenants of the Building.

                                   ARTICLE 11
                            ASSIGNMENT AND SUBLETTING

         11.1 Consent. Tenant shall not assign, transfer, mortgage or otherwise
encumber this Lease or sublet or rent (or permit a third party to occupy or use)
the Premises, or any part thereof, nor shall any assignment or transfer of this
Lease or the right of occupancy hereunder be effected by operation of law or
otherwise, without the prior written consent of Landlord which shall not be
unreasonably withheld or delayed. Without limitation, it shall not be
unreasonable for Landlord to deny its consent to any proposed assignment or
sublease if, at the time receives Tenant's Proposal Notice (defined below), an
Event of Default is then continuing under this Lease. Tenant must request
Landlord's consent to such assignment or sublease in writing at least thirty
(30) days prior to the commencement date of the proposed sublease or assignment,
which written request (a "Proposal Notice") must include (a) the name and
address of the proposed assignee or subtenant, (b) the nature and character of
the business of the proposed assignee or subtenant, (c) financial information
(including financial statements) of the proposed assignee or subtenant, and (d)
a copy of the proposed sublease or assignment agreement. Tenant shall also
provide any additional information Landlord reasonably requests regarding such
proposed assignment or subletting. For purposes of the foregoing prohibitions,
but subject to the permissive rights provided for under Section 11.3, below, a
transfer at any one time or in a series of "step transactions" of more than
fifty percent (50%) of an interest in Tenant (whether stock, partnership
interest or other form of ownership or control) by any person(s) or entity(ties)
having an interest in ownership or control of Tenant at the Date of Lease shall
be deemed to be an assignment of this Lease. If Landlord consents to the
proposed assignment or subletting, the initial Tenant and any Guarantor shall
remain liable under this Lease. Any assignment, encumbrance, or sublease without
Landlord's written consent shall be voidable by Landlord and, at Landlord's
election, constitute an Event of Default hereunder. Neither the consent by
Landlord to any assignment, transfer, encumbrance or subletting nor the
collection or acceptance by Landlord of rent from any assignee, subtenant or
occupant shall be construed as a waiver or release of the initial Tenant or any
Guarantor from the terms and conditions of this Lease or relieve Tenant or any
subtenant, assignee or other party from obtaining the consent in writing of
Landlord to any further assignment, transfer, encumbrance or subletting. Tenant
hereby assigns to Landlord the rent and other sums due from any subtenant,
assignee or other occupant of the Premises and hereby authorizes and directs
each such subtenant, assignee or other occupant to pay such rent or other sums
directly to Landlord; provided, however, that until the occurrence of an Event
of Default, Tenant shall have the license to continue collecting such rent and
other sums. In addition, with respect to any sublease or assignment by Tenant,
Tenant hereby assigns and agrees to pay to Landlord one-half (1/2) of the amount
by which the subrent or other consideration directly or indirectly received by
Tenant with respect to the applicable space from any subtenant or assignee
exceeds the Rent allocable thereto, calculated after subtracting the amount of
all out-of-pocket expenses paid by Tenant directly in connection with such
sublease or assignment (including as legal expenses and leasing commissions
arising out of the sublease, subleasehold improvements costs, etc.).

       11.2 Affiliated Entity; Sale of Business. Notwithstanding Section 11.1
to the contrary, but provided (a) an Event of Default shall not then be
continuing under this Lease, (b) such transfer is not effectuated as part of a
transaction or series of transfers orchestrated in order to effect a transfer of
this Lease (or Tenant's interest herein) in isolation to Tenant's other
leasehold interests and assets, (c) the creditworthiness of Tenant is not
diminished thereby, and (d) both Tenant and the assignee or sublessee (as the
case may be) remain fully liable for the obligations of Tenant under this Lease,
Tenant shall have the right, without Landlord's prior written consent, to assign
this Lease or sublet the Premises to (i) any wholly owned subsidiary of Tenant
or to any parent 


                                       12


<PAGE>   13

corporation of Tenant, or (ii) any affiliate or entity otherwise under common
control with Tenant or any affiliate or entity under common control with a
parent or subsidiary of Tenant, control being understood to mean ownership of
more than 50% of the beneficial interests of an entity together with the
exclusive right to exercise voting control over the management and operation of
the entity in question, or (iii) any entity which acquires all or substantially
all of the assets or stock of Tenant, by merger, consolidation, acquisition or
other business reorganization. An "affiliate" shall mean any corporations or
other business entities which control, are controlled by, or are under common
control with the entity in question, as the term control is defined above.
Tenant shall give Landlord written notice of any such sublease or assignment
promptly after the same is effectuated. Any provision of the foregoing sections
of this Article 11 to the contrary notwithstanding, Landlord agrees that the
offer and sale by Tenant (or any stockholder of Tenant) of any stock pursuant to
an effective registration statement filed pursuant to the Securities Act of 1933
(including any initial public offering of registered stock of the Tenant) shall
not constitute an assignment of this Lease, and shall not require the consent or
approval of Landlord. The initial Tenant and any transferee pursuant to a
sublease, assignment or transfer made in accordance with this Section 11.2 shall
be jointly and severally liable for the obligations of "Tenant" under the Lease
from and after the date of such sublease, assignment and/or transfer, including
the obligation to comply with the provisions of this Article 11 with regard to
any subsequent sublease, assignment or transfer.

                                   ARTICLE 12
                             MAINTENANCE AND REPAIR

         12.1 Landlord's Obligations. As long as no Event of Default by Tenant
has occurred and is continuing, Landlord shall, at its expense, maintain the
roof, foundation and the structural soundness of the exterior walls of the
Building in good repair, reasonable wear and tear excepted. Tenant shall repair
and pay for any damage caused by the negligence of Tenant or Tenant's employees,
agents or invitees, or caused by Tenant's default hereunder. The term "walls" as
used in this Section shall include windows, glass and doors which are part of
the exterior walls of the Building. Tenant shall immediately give Landlord
written notice of any defect or need for repairs, and after such notice,
Landlord shall have a reasonable opportunity to repair or cure such defect,
provided in the event of a bona fide emergency involving an imminent risk of
death or injury to persons or material damage to property (an "Emergency"), and
provided (i) such action will not interfere with the other occupants of the
Building or the use of their respective premises or jeopardize their health,
safety or welfare, and (ii) Landlord has not already commenced curative action,
Tenant shall be empowered to undertake immediate repairs of such nature as would
be Landlord's responsibility and in such event, Tenant shall notify Landlord
promptly after such repairs have been undertaken. If Landlord fails to proceed
to repair or maintain the Premises with reasonable diligence and within the
reasonable time period referenced above, or if Tenant undertakes Emergency
repairs as above stated and such Emergency was not brought about by the
negligence or willful misconduct of Tenant or Tenant's Agents, then Tenant may,
in addition to any other remedies Tenant may have at law or in equity, perform
such repairs or maintenance and charge Landlord for the reasonable and actual
cost thereof (which charge (A) shall be communicated by formal written notice
accompanied by all invoices and other documentation evidencing the need for and
scope of such repairs, and if applicable, the basis for Tenant's determination
that an Emergency existed, and (B) shall, solely to the extent it arises in the
context of an Emergency , and not as a result of Landlord's failure to proceed
with the repair with due diligence and within the fifteen (15) business day
period provided herein, be included within Common Area Expenses under this Lease
to the extent the same is in fact reimbursed by Landlord and would have been
included as a Common Area Expense had the same been performed by Landlord
pursuant hereto). Landlord shall either reimburse to Tenant the amount so
requested by Tenant, or dispute in writing Tenant's right to have undertaken the
repair(s) in question, or the reasonableness of the costs incurred by Tenant in
undertaking such repair(s) (by written notice delivered to Tenant), within
thirty (30) days after receipt of Tenant's invoice and documentation justifying
Tenant's expenditure of such amount; and if Landlord fails to deliver either a
notice of dispute or the required payment within such thirty (30) day period,
Tenant shall thereafter have the right to deduct the amount reflected within
such invoice from the next payments of Base Rent and Additional Rent becoming
due hereunder. To the extent Landlord only disputes a portion of Tenant's
invoice, Landlord shall indicate same in its notice of dispute and shall pay the
undisputed portion within such thirty (30) day period. If disputed by Landlord
in a timely fashion, 

                                       13


<PAGE>   14

Tenant shall have no right of offset until after receiving a final, non-
appealable judgment in its favor with respect to such claim provided such
final non-appealable judgment remains unpaid for a period of thirty (30) days.
Tenant shall immediately give Landlord written notice of any defect or need for
repairs. After such notice, Landlord shall have a reasonable opportunity to
repair or cure such defect. Landlord's liability with respect to any defects,
repairs or maintenance for which Landlord is responsible under any of the
provisions of this Lease shall be limited to the cost of such repairs or
maintenance or the curing of such defect.

         12.2 Tenant's Obligations. Subject to Article 21 of this Lease, Tenant
shall, at its own expense, maintain all parts of the Premises (except those for
which Landlord is either expressly responsible or elects to undertake pursuant
to Section 12.1 or 12.3 of this Lease) in good condition, promptly making all
necessary repairs and replacements, including, but not limited to, any special
office entry, interior walls and finish work, floors and floor covering,
interior downspouts, interior lighting and interior electric systems, HVAC
systems (including fixtures and equipment), plumbing work and fixtures, termite
and pest extermination, and regular removal of trash and debris (unless
undertaken by Landlord). Tenant shall, at its own expense, keep the sidewalks in
front of the Premises free from obstructions of any and all nature, keep the
Premises in a clean and sanitary condition, maintain suitable receptacles within
the Premises for trash and refuse, and promptly remove from the Premises all
accumulations of trash and refuse. In order to fulfill the immediately foregoing
obligations, Tenant shall, at its expense, enter into a contract for janitorial
and/or char service with a contractor reasonably acceptable to Landlord. Unless
otherwise provided for by Landlord, Tenant shall, at its expense, enter into a
regularly scheduled preventive maintenance/service contract for all hot water,
heating and air conditioning systems and equipment within the Premises. The
maintenance contractor, the contract and the maintenance schedule must be given
prior approval in writing by Landlord. The service contract must include all
services suggested by the equipment manufacturer in the operation/maintenance
manual and must become effective (and a copy thereof delivered to Landlord)
within thirty (30) days of the date Tenant takes possession of the Premises.
Without the prior written consent of the Landlord, Tenant shall not have access
to the roof of the Building for any purpose whatsoever except as provided in
Section 29.2, below.

         12.3 Landlord's Right to Maintain or Repair. If, within fifteen (15)
business days following notice to Tenant, Tenant fails to commence to repair or
replace any damage to the Premises or Building which is Tenant's obligation to
perform, and diligently pursue timely completion of such repair and replacement,
and upon written notice to Tenant of its intention to do so (except in cases of
Emergency, in which event Landlord shall be empowered, but not obligated, to act
immediately to the extent necessary to avoid or minimize the risk of death or
injury to persons or material damage to Property), Landlord may, at its option,
cause all required maintenance, repairs or replacements to be made. Tenant shall
promptly pay Landlord all costs incurred in connection therewith plus interest
thereon at the Interest Rate from the due date until paid.

         12.4 Compliance with Laws. Tenant, at Tenant's sole expense, shall
comply with all laws, rules, orders, ordinances, directions, regulations and
requirements of federal, state, county and municipal authorities now in force or
which may hereafter be in force, which shall impose any duty upon Landlord or
Tenant with respect to the use, occupancy or alteration of the Premises or with
respect to the repair, maintenance and replacement of the Premises (hereinafter,
"Applicable Laws"). Notwithstanding the foregoing, Landlord (at its sole expense
except as provided in Article 7, above) and not Tenant, shall be required to (i)
perform any modifications required by Applicable Laws to the Building Shell
(i.e., structural components, the exterior cladding or perimeter glass) or
Building systems (excluding Tenant's modifications thereto), and (ii) cure any
non-compliance of the Premises existing as of the Commencement Date with regard
to Applicable Laws in effect as of the Commencement Date, including building and
fire/life safety codes, except to the extent such modifications or curative
actions are required as a result of (i) Tenant's requirements for the Tenant
Improvements constructed pursuant to Exhibit B, (ii) any Alterations performed
by or at the request of Tenant, (iii) Tenant's particular use of the Premises to
the extent the same is not general office use, (iv) any special equipment
installed by Tenant within the Premises, or (v) any other acts or omissions of
Tenant or Tenant's Agents.


                                       14

<PAGE>   15

                                   ARTICLE 13
                        INITIAL CONSTRUCTION; ALTERATIONS

         13.1 Initial Construction. Landlord and Tenant agree that the
construction of the Tenant Improvements (as defined in Exhibit B attached hereto
and made a part hereof) and other initial construction with respect to the
Premises shall be performed in accordance with Exhibit B.

         13.2 Alterations. Tenant shall not make or permit any Alterations
without the prior written consent of Landlord, other than minor interior
cosmetic Alterations which do not involve the issuance of a building permit and
which do not affect the exterior of, or any structural elements or mechanical,
electrical, plumbing and HVAC systems within, the Building. Landlord may impose
any reasonable conditions to its consent, including, without limitation, (i)
delivery to Landlord of written or unconditional waivers of mechanic's and
materialmen's liens as to the Premises, the Building and the Land for all work,
labor and services to be performed and materials to be furnished, signed by all
contractors, subcontractors, materialmen and laborers participating in the
Alterations, (ii) prior approval of the plans and specifications and Tenant's
contractor(s) with respect to the Alterations, and (iii) supervision by
Landlord's representative (at Tenant's expense, not to exceed 3% of the cost
thereof) of the Alterations. The Alterations shall conform to the requirements
of Landlord's and Tenant's insurers and of the Federal, state and local
governments having jurisdiction over the Premises, shall be performed in
accordance with the terms and provisions of this Lease in a good and workmanlike
manner befitting a first class office building and shall not adversely affect
the value, utility or character of the Premises. If the Alterations are not
performed as herein required, Landlord shall have the right, at Landlord's
option, to halt any further Alterations, or to require Tenant to perform the
Alterations as herein required or to require Tenant to return the Premises to
its condition before such Alterations. Notwithstanding the foregoing, if any
mechanic's or materialmen's lien is filed against the Premises, the Building or
the Land for work claimed to have been done for, or materials claimed to have
been furnished to or for the benefit of, Tenant, such lien shall be discharged
of record by Tenant within ten (10) days by the payment thereof or the filing of
any bond required by law. If Tenant shall fail to discharge any such lien,
Landlord may (but shall not be obligated to) discharge the same, the cost of
which shall be paid by Tenant within three (3) days of demand by Landlord. Such
discharge by Landlord, shall not be deemed to waive or release the default of
Tenant in not discharging the same. Neither Landlord's consent to the
Alterations nor anything contained in this Lease shall be deemed to be the
agreement or consent of Landlord to subject Landlord's interest in the Premises,
the Building or the Land to any mechanic's or materialmen's liens which may be
filed in respect of the Alterations.

         13.3 Removal of Alterations. Except to the extent Tenant requests and
Landlord designates otherwise at the time Landlord approves such Alterations,
all or any part of the Alterations made after the Commencement Date of this
Lease (including, without limitation, wall-to-wall carpet and wiring), whether
made with or without the consent of Landlord, shall, at the election of
Landlord, either be removed by Tenant at its expense before the expiration of
the Term or shall remain upon the Premises and be surrendered therewith at the
Expiration Date or earlier termination of this Lease as the property of Landlord
without disturbance, molestation or injury. If Landlord requires the removal of
all or part of the Alterations, Tenant, at its expense, shall repair any damage
to the Premises or the Building caused by such removal. If Tenant fails to
remove the Alterations upon Landlord's request, then Landlord may (but shall not
be obligated to) remove the same and the cost of such removal and repair of any
damage caused by the same, together with any and all damages which Landlord may
suffer and sustain by reason of the failure of Tenant to remove the same, shall
be charged to Tenant and paid upon demand.

         13.4 Landlord Alterations. Landlord shall have no obligation to make
any Alterations in or to the Premises, the Building, the Common Area or the Land
except as specifically provided in the Work Agreement.


                                       15

<PAGE>   16

                                   ARTICLE 14
                                      SIGNS

         14.1 General Sign Provision. Except as expressly permitted hereby, no
sign, advertisement or notice shall be inscribed, painted, affixed, placed or
otherwise displayed by Tenant on any part of the Land or the outside or the
inside (including, without limitation, the windows) of the Building or the
Premises. Any permitted signs shall be installed and maintained by Landlord at
Tenant's sole expense. All signage shall be in compliance with all applicable
laws and ordinances, and all covenants, conditions and restrictions applicable
to the Dulles Business Park. If any prohibited sign, advertisement or notice is
nevertheless exhibited by Tenant, Landlord shall have the right to remove the
same, and Tenant shall pay any and all expenses incurred by Landlord in such
removal, together with interest thereon at the Interest Rate, upon demand.
Landlord shall have the right to prohibit any sign, advertisement, notice or
statement to the public by Tenant which, in Landlord's opinion, tends to impair
the reputation of the Building or its desirability as a first class office
building.

         14.2 Special Sign Rights. Section 14.1 to the contrary notwithstanding,
Landlord agrees, pursuant to and subject to the provisions of Exhibit B, but in
all events subject to all applicable laws and ordinances, all covenants,
conditions and restrictions applicable to the Dulles Business Park including the
Declaration, and any general signage program applicable to the Dulles Business
Park, to provide Tenant with exclusive exterior signage rights on eastern and
southern exterior facades of the Building, which will permit the installation by
Tenant (at its expense) of a single exterior building identification sign on
each such facade, identifying Tenant by name and/or corporate logo, to be
located at the top of the Building at a location designated by Landlord subject
to Tenant's reasonable consent, and subject to the prior rights to exterior
signage in favor of ECS (as such term is defined herein), to the extent
permitted by applicable law.

                                   ARTICLE 15
                         TENANT'S EQUIPMENT AND PROPERTY

         15.1 Moving Tenant's Property. Any and all damage or injury to the
Premises or the Building caused by moving the property of Tenant into or out of
the Premises, or due to the same being on the Premises, shall be repaired by
Landlord, at the expense of Tenant. Tenant shall promptly remove from the Common
Area any of Tenant's furniture, equipment or other property there deposited.

         15.2 Installing and Operating Tenant's Equipment. Without first
obtaining the written consent of Landlord, which consent shall not be
unreasonably withheld, Tenant shall not install or operate in the Premises (i)
any electrically operated equipment or other machinery, other than standard
office equipment that does not require wiring, cooling or other service in
excess of Building standards, (ii) any equipment of any kind or nature
whatsoever which will require any material changes, replacements or additions
to, or changes in the use of, any water, heating, plumbing, air conditioning or
electrical system of the Premises or the Building, or (iii) any equipment which
causes the floor load to exceed a load limit which is reasonably appropriate for
a "concrete slab-on grade" one story building. Machines and equipment which
cause noise or vibration that may be transmitted to the structure of the
Building or to any space therein so as to be objectionable to Landlord or any
other Building tenant shall be installed and maintained by Tenant, at its
expense, on vibration eliminators or other devices sufficient to eliminate such
noise and vibration.

                                   ARTICLE 16
                                 RIGHT OF ENTRY

         Tenant shall permit Landlord or its Agents, at any time and upon one
(1) business days prior notice (which may include non-written notice for minor
entries not likely to cause a significant disturbance to Tenant's quiet
enjoyment), and without notice in the event of an Emergency, to enter the
Premises, without charge therefor to Landlord and without diminution of Rent,
(i) to examine, inspect and protect the Premises and the Building, 


                                       16


<PAGE>   17

(ii) to make such alterations and repairs or perform such maintenance which in
the sole but reasonable judgment of Landlord may be deemed necessary or
desirable, (iii) to exhibit the same to prospective purchasers of the Building
or to present or future Mortgagees or (iv) to exhibit the same to prospective
tenants during the last twelve (12) months of the Term and to erect on the
Premises a suitable sign indicating the Premises are available. Nothing set
forth in this Article 16 shall be deemed to diminish Landlord's obligation (if
any) to provide rental reduction or abatement pursuant to Sections 18.3 or 21.1
of this Lease, to the extent such Sections are by their terms applicable in the
context of a Landlord entry pursuant to this Article 16.


                                   ARTICLE 17
                                    INSURANCE

         17.1 Insurance Rating. Tenant shall not conduct or permit any activity,
or place any equipment or material, in or about the Premises, the Building or
the Common Area which will increase the rate of fire or other insurance on the
Building or insurance benefitting any other tenant of the Building; and if any
increase in the rate of insurance is determined by any insurance company or by
the applicable insurance rating bureau to be due to any activity, equipment or
material of Tenant in or about the Premises, the Building or the Common Area,
such determination shall be conclusive evidence that the increase in such rate
is due to the same and, as a result thereof, Tenant shall pay such increase to
Landlord upon demand.

         17.2 Liability Insurance. Tenant shall, at its sole cost and expense,
procure and maintain throughout the Term a commercial general liability policy
insuring against claims, demands or actions for bodily injury, death, personal
injury, and loss or damage to property arising out of or in connection with: (i)
the Premises; (ii) the condition of the Premises; (iii) Tenant's operations in,
maintenance and use of the Premises, Building and Common Area, and (iv) Tenant's
liability assumed under this Lease. Such insurance shall have such combined
single limit as reasonably required by Landlord from time to time, but in no
event less than Two Million Dollars ($2,000,000.00) per occurrence, on an
occurrence basis, and shall be primary over any insurance carried by Landlord.
Endorsements shall be obtained for cross-liability and contractual liability.

         17.3 Insurance for Personal Property. Tenant shall, at its sole cost
and expense, procure and maintain throughout the Term a property insurance
policy (written on an "All Risk" basis) insuring all of Tenant's personal
property, including but not limited to equipment, furniture, fixtures,
furnishings and leasehold improvements which are the responsibility of Tenant,
for not less than the full replacement cost of said property. All proceeds of
such insurance shall be used to repair or replace Tenant's property. In
addition, Tenant shall, at its sole cost and expense, procure and maintain
business interruption insurance in an amount not less than the Base Rent due
hereunder for the first Lease Year.

         17.4 Requirements of Insurance Coverage. All such insurance required to
be carried by Tenant herein shall be with an insurance company licensed to do
business in the Commonwealth of Virginia and rated not lower than A-XII in the
A.M. Best Rating Guide. Such insurance (i) shall contain an endorsement that
such policy shall remain in full force and effect notwithstanding that the
insured has released its right of action against any party before the occurrence
of a loss; (ii) shall name Landlord and, at Landlord's request, any Mortgagee or
ground lessor, as additional insured parties; and (iii) shall provide that the
policy shall not be canceled, failed to be renewed or materially amended without
at least thirty (30) days' prior written notice to landlord and, at Landlord's
request, any Mortgagee. On or before the Commencement Date and, thereafter, not
less than thirty (30) days before the expiration date of the insurance policy, a
certificate evidencing such policy (including any renewal or replacement policy)
which shall expressly allow Landlord to rely thereupon, together with evidence
satisfactory to Landlord of the payment of all premiums for such policy, shall
be delivered to Landlord and, at Landlord's request, to any Mortgagee.


                                       17

<PAGE>   18


         17.5 Waiver of Subrogation. Each party hereby releases the other party
hereto from liability for any loss or damage to any building, structure or
tangible personal property, or any resulting loss of income, or losses under
worker's compensation laws and benefits, notwithstanding that such loss, damage
or liability may arise out of the negligent or intentionally tortious act or
omission of the other party or its Agents, if such loss or damage is covered by
insurance benefitting the party suffering such loss or damage or was required to
be covered by insurance pursuant to this Lease. Each party hereto shall use
reasonable efforts to have a waiver of subrogation clause (providing that such
waiver of right of recovery against the other party shall not impair the
effectiveness of such policy or the insured's ability to recover) included in
its said policies, and shall promptly notify the other in writing if such clause
cannot be included in any such policy; if such waiver of subrogation clause
shall not be available, then the foregoing waiver of right of recovery shall be
void.

         17.6 Security. In the event that Landlord engages the services of a
professional security system for the Building, it is understood that such
engagement shall in no way increase Landlord's liability for occurrences and/or
consequences which such a system is designed to detect or avert and that Tenant
shall look solely to its insurer as set out above for claims for damages or
injury to any person or property. In no event shall this Section 17.6, nor any
other provision of this Lease, be construed to create any express or implied
obligation on the part of Landlord to secure Project, Premises, Building or
Common Areas, or otherwise provide security services for the Project, Premises,
Building or Common Areas.

         17.7 Landlord's Insurance. At all times during the Lease Term, Landlord
will maintain, as a Common Area Expense hereunder, (a) fire and extended
coverage insurance covering the Building, including all of the Tenant
Improvements, in an amount equal to one hundred percent (100%) of the
replacement value thereof, (b) public liability and property damage insurance of
the types and amounts described in Section 12. 1, above, or such greater amounts
as Landlord may deem prudent or as are necessary to satisfy the requirements of
Landlord's Mortgagee, if any, and (c) rent loss insurance in an amount equal to
not less than twelve (12) months rent for the Building. Landlord shall also have
the right to obtain such other types and amounts of insurance coverage on the
Building and Landlord's liability in connection with the Building as are
customary or advisable for comparable office/flex projects in the
Chantilly/Dulles area of Fairfax County, Virginia, as determined by Landlord in
Landlord's reasonable judgment based on then current insurance industry products
and practices. Such insurance shall contain commercially reasonable deductibles
as are customary or advisable for comparable office/flex projects in the
Chantilly/Dulles area of Fairfax County, Virginia.

                                   ARTICLE 18
                         LANDLORD SERVICES AND UTILITIES

         18.1 Ordinary Services to the Premises. Landlord shall maintain the
Common Areas (including exterior of the Building and the Land) in a manner
consistent with other similar first class office/flex projects in the general
vicinity of the Building in Chantilly/Dulles area of Fairfax County, Virginia.
Landlord agrees to furnish landscaping, grounds maintenance, and snow clearing
for the areas used in common by the tenants of the Building. In addition,
Landlord shall arrange for trash removal from common exterior trash dumpsters
serving the Building, into which Tenant's interior trash shall be deposited by
Tenant (and/or Tenant's janitorial service contractor) pursuant to reasonable
rules and regulations governing such trash removal as Landlord may establish in
accordance with applicable law (which may, if applicable, include a requirement
that Tenant comply at Tenant's expense with federal, state and/or local
requirements applicable to trash recycling). All of the foregoing services shall
be furnished by Landlord and reimbursed by Tenant as part of Common Area
Expenses. Subject to Section 18.3, below, Landlord shall be under no
responsibility or liability for failure or interruption in such services whether
caused by breakage, accident, strikes, repairs or for any other cause or causes
beyond the control of Landlord, nor in any event for any indirect or
consequential damages; and failure or omission on the part of Landlord to
furnish such service shall not be construed as an eviction of Tenant, nor work
an abatement of Rent, nor render Landlord liable in damages, nor release Tenant
from prompt fulfillment of any of the covenants under this Lease.


                                       18

<PAGE>   19

         18.2 Utility Charges. All telephone, electricity, gas, heat and other
utility service furnished to the Premises shall be paid for by Tenant except to
the extent the cost of same is included within Common Area Expenses. Landlord
shall cause electrical service to the Premises to be separately metered or
measured. The cost of any such meter shall he borne by Tenant in accordance with
Exhibit B.

         18.3 Interruption in Services. Notwithstanding any provision of this
Article 18 to the contrary, in the event that the supply of water or electricity
(individually an "Essential Service," and collectively, the "Essential
Services") to the Premises is interrupted as a result of the negligence or
willful misconduct of Landlord, or its Agents, (and not as a result of any cause
beyond Landlord's reasonable control, such as a general electrical outage or
blackout) and such interruption continues for a period exceeding three (3)
consecutive business days after Tenant first notifies Landlord of such
interruption in writing, and as a result thereof Tenant is unable to and does
not in fact conduct business from the Premises or any applicable portion
thereof, then from and after such third (3rd) consecutive business day, Tenant
shall be entitled to abate its Rent and additional rent obligations hereunder as
to the Premises or portion thereof which is not usable (and not used) until such
time as the applicable Essential Service is restored. Other than Tenant's right
to perform Landlord's obligations after a default by Landlord, and to be
reimbursed for the cost of such performance, the foregoing shall constitute
Tenant's sole and exclusive remedy in the event of an interruption of the
services described in this Article 18 (including any Essential Services) to the
Premises.

                                   ARTICLE 19
                              LIABILITY OF LANDLORD

         19.1 No Liability. Except where due to Landlord or its Agents' gross
negligence or willful misconduct, and except as provided in Section 18.3, above,
Landlord and its Agents shall not be liable to Tenant or its Agents for, and
Tenant, for itself and its Agents, does hereby release Landlord and its Agents
from liability for, any damage, compensation or claim arising from (i) the
necessity of repairing any portion of the Premises or the Building or the Common
Area or any structural defects thereto, (ii) any interruption in the use of the
Premises or the Common Area for any reason including any interruption or
suspension of utility service, (iii) fire or other casualty or personal or
property injury, damage or loss resulting from the use or operation (by
Landlord, Tenant, or any other person whomsoever) of the Premises or the
Building or the Common Area, (iv) any robbery, assault, theft or other criminal
act, or (v) any leakage in the Premises or the Building from water, rain, snow
or other cause whatsoever. Except as expressly provided herein, no such
occurrence shall give rise to diminution or abatement of Rent or constructive
eviction. Notwithstanding the foregoing, any goods, automobiles, property or
personal effects stored or placed by Tenant or its Agents in or about the
Premises, the Building or the Common Area shall be at the sole risk of Tenant;
Tenant hereby expressly waives its right to recover against Landlord and its
Agents therefor. Tenant hereby waives any claim it might have against Landlord
or its Agents for any consequential damages or business losses sustained by
Tenant arising out of the loss or damage to any person or property of Tenant, or
any interruption in the use of the Premises or the Common Area, for any reason.
Tenant acknowledges its obligation to insure against such losses and damages.

         19.2 Tenant's Indemnity. Tenant shall indemnify, defend, protect and
hold Landlord and its Agents harmless from and against any and all damages,
claims, liabilities, costs or expenses (including, without limitation,
attorneys' or other professionals' fees) of every kind and nature (including,
without limitation, those arising from any injury or damage to any person,
property or business) claimed against Landlord or its Agents by any third party
or sustained by Landlord and its Agents in favor of any third party, directly or
indirectly, as a result of, arising from or in connection with (i) Tenant's or
its Agents' use and occupancy of the Premises, (ii) Tenant's breach of any
provision of this Lease; or (iii) any act, omission or negligence of Tenant or
its Agents.

         19.3 Landlord's Indemnity. Landlord shall indemnify, defend, protect
and hold Tenant and its Agents harmless from and against any and all damages,
claims, liabilities, costs or expenses (including, without limitation,
attorneys' or other professionals' fees) of every kind and nature (including,
without limitation, those arising from any injury or damage to any person,
property or business) claimed against Tenant or its Agents by any third party or
sustained by Tenant or its Agents in favor of any third party, directly or
indirectly, as a result 

                                       19



<PAGE>   20

of, arising from or in connection with (i) Landlord's breach of any provision of
this Lease; or (ii) any act, omission or negligence of Landlord or its Agents.

                                   ARTICLE 20
                              RULES AND REGULATIONS

         Tenant and its Agents shall at all times abide by and observe the Rules
and Regulations and any amendments thereto that may be promulgated from time to
time by Landlord for the operation and maintenance of the Building and the
Common Area and the Rules and Regulations shall be deemed to be covenants of the
Lease to be performed and/or observed by Tenant. Nothing contained in this Lease
shall be construed to impose upon Landlord any duty or obligation to enforce the
Rules and Regulations, or the terms or provisions contained in any other lease,
against any other tenant of the Building. Landlord shall not be liable to Tenant
for any violation by any party of the Rules and Regulations or the terms of any
other Building lease. If there is any inconsistency between this Lease and the
Rules and Regulations, this Lease shall govern. Landlord reserves the right to
amend and modify the Rules and Regulations as it deems necessary. Landlord
agrees that it shall not enforce any such Rules and Regulations against Tenant
in a discriminatory fashion.

                                   ARTICLE 21
                              DAMAGE; CONDEMNATION

         21.1 Damage to the Premises. If the Premises shall be damaged by fire
or other cause without the fault or negligence of Tenant or its Agents, Landlord
shall diligently and as soon as practicable after such damage occurs (taking
into account the time necessary to effect a satisfactory settlement with any
insurance company involved) repair such damage at the expense of Landlord;
provided, however, that Landlord's obligation to repair such damage shall not
exceed the proceeds of insurance available to Landlord (reduced by any proceeds
retained pursuant to the rights of Mortgagee). Notwithstanding the foregoing, if
the Premises or the Building is damaged by fire or other cause to such an extent
that, in Landlord's sole but reasonable judgment, the damage cannot be
substantially repaired within one hundred eighty (180) days after the date of
such damage, or if the Premises are damaged during the last two (2) Lease Years,
then Landlord or Tenant within thirty (30) days from the date of such damage may
terminate this Lease by notice to the other. If either Landlord or Tenant
terminates this Lease, the Rent shall be apportioned and paid to the date of
such termination. If neither Landlord nor Tenant so elects to terminate this
Lease but the damage required to be repaired by Landlord is not repaired within
one hundred eighty (180) days from the date of such damage (such one hundred
eighty (180) day period to be extended by the period of any delay outside the
direct control of Landlord plus a reasonable period for a satisfactory
settlement with any insurance company involved), Tenant, within thirty (30) days
from the expiration of such one hundred eighty (180) day period (as the same may
be extended), may terminate this Lease by notice to Landlord. During the period
that Tenant is deprived of the use of the damaged portion of the Premises for
the normal operation of its business (and in facts ceases such use), and
provided such damage is not the consequence of the gross negligence of Tenant or
its Agents, Base Rent and Tenant's Proportionate Share shall be reduced by the
ratio that the rentable square footage of the Premises for which Tenant is
deprived of use for normal business purposes (and in facts ceases such use) by
virtue of such damage bears to the total rentable square footage of the Premises
before such damage. All injury or damage to the Premises or the Building
resulting from the fault or negligence of Tenant or its Agents shall be repaired
by Tenant, at Tenant's expense, and Rent shall not abate. If Tenant shall fail
to do so or if Landlord shall so elect, Landlord shall have the right to make
such repairs, and any expense so incurred by Landlord, together with interest
thereon at the Interest Rate, shall be paid by Tenant upon demand.
Notwithstanding anything herein to the contrary, Landlord shall not be required
to rebuild, replace or repair any non-standard tenant improvements, tenant
extras or Alterations or any personal property of Tenant.

         21.2 Condemnation. If the whole or a Substantial Part of the Premises
or the Building shall be taken or condemned by any governmental or
quasi-governmental authority for any public or quasi-public use or purpose
(including, without limitation, sale under threat of such a taking), then the
Term shall cease and terminate as of the date when title vests in such
governmental or quasi-governmental authority, and Rent shall be prorated to the
date when title vests in such governmental or quasi-governmental authority. If
less than a

                                       20

<PAGE>   21

Substantial Part of the Premises is taken or condemned by any governmental or
quasi-governmental authority for any public or quasi-public use or purpose
(including, without limitation, sale under threat of such a taking), Base Rent
and Tenant's Proportionate Share shall be reduced by the ratio that the portion
so taken bears to the rentable square footage of the Premises before such
taking, effective as of the date when title vests in such governmental or
quasi-governmental authority, and this Lease shall otherwise continue in full
force and effect. Tenant shall have no claim against Landlord (or otherwise) as
a result of such taking, and Tenant hereby agrees to make no claim against the
condemning authority for any portion of the amount that may be awarded as
compensation or damages as a result of such taking; provided, however, that
Tenant may, to the extent allowed by law, claim an award for moving expenses and
for the taking of any of Tenant's property (other than its leasehold interest in
the Premises) which does not, under the terms of this Lease, become the property
of Landlord at the termination hereof, as long as such claim is separate and
distinct from any claim of Landlord and does not diminish Landlord's award.
Tenant hereby assigns to Landlord any right and interest it may have in any
award for its leasehold interest in the Premises.

                                   ARTICLE 22
                                     DEFAULT

         22.1 Events of Default. Each of the following shall constitute an
"Event of Default": (i) Tenant fails to pay Rent within five (5) days after
written notice from Landlord; provided that no such notice shall be required if
at least two such notices shall have been given during the same Lease Year; (ii)
Tenant fails to observe or perform any other term, condition or covenant herein
binding upon or obligating Tenant within fifteen (15) business days after
written notice from Landlord (or, in the case of any such failure which cannot
with due diligence be cured within fifteen (15) business days, within such
additional period, if any, as may be reasonably required by Tenant to cure such
failure with due diligence provided Tenant promptly commences such cure and
diligently pursues such cure to a successful completion) provided, however, that
the foregoing cure period shall not be invoked in cases of Emergency to prevent
Landlord from exercising its rights under Section 22.5 below to perform an
obligation which Tenant has failed to perform under this Lease on Tenant's
behalf (and at Tenant's expense) to the extent necessary to eliminate the
imminent risk of death or injury to persons or material damage to Property, as
determined by Landlord in its sole, but reasonable, judgment; (iii) Tenant
abandons or vacates the Premises (unless Tenant has secured the Premises, is
continuing to maintain the Premises so as to prevent waste or deterioration
thereto, is current in the payment of Rent under this Lease, and is not
otherwise in default hereunder, in which event Tenant's mere vacating of the
Premises shall not, by itself, constitute an Event of Default; (iv) Tenant or
any Guarantor makes or consents to a general assignment for the benefit of
creditors or a common law composition of creditors, or a receiver of the
Premises or all or substantially all of Tenant's or Guarantor's assets is
appointed, or (v) Tenant or Guarantor files a voluntary petition in any
bankruptcy or insolvency proceeding, or an involuntary petition in any
bankruptcy or insolvency proceeding is filed against Tenant or Guarantor and is
not discharged by Tenant or Guarantor within sixty (60) days. To the extent
Tenant is entitled to a written notice of any failure of performance or default
by it pursuant to this Section 22.1, Landlord agrees to provide concurrent
notice of such failure or default to Guarantor, at the notice address set forth
herein.

         22.2 Landlord's Remedies. Upon the occurrence of an Event of Default,
Landlord, at its option, without further notice or demand to Tenant, may to the
fullest extent permitted by law, and in addition to all other rights and
remedies provided in this Lease, at law or in equity:

         (i) Terminate this Lease and Tenant's right of possession of the
Premises, and recover all damages to which Landlord is entitled under law,
specifically including, but without limitation, all of Landlord's expenses of
reletting (including, without limitation, rental concessions to new tenants,
repairs, Alterations, legal fees and brokerage commissions). In addition, if
Landlord elects to terminate this Lease, every obligation of Landlord hereunder
shall cease as of the date of such termination, but the same shall not affect
the liability of Tenant for payment of Rent and performance of all other terms
and conditions of this Lease to the date of termination, plus any damages and/or
other sums recoverable by Landlord under this Article 22 or otherwise at law or
in equity.

                                       21
<PAGE>   22



1


         (ii) Terminate Tenant's right of possession of the Premises without
terminating this Lease, which termination of possession shall be by applicable
legal process, in which event Landlord may, but shall not be obligated to, relet
the Premises, or any part thereof, for the account of Tenant, for such rent and
term and upon such other conditions as are acceptable to Landlord. For purposes
of such reletting, Landlord is authorized to redecorate, repair, alter and
improve the Premises to the extent necessary in Landlord's sole discretion.
Until Landlord relets the Premises, Tenant shall remain obligated to pay Rent to
Landlord as provided in this Lease. If and when the Premises are relet and if a
sufficient sum is not realized from such reletting after payment of all
Landlord's expenses of reletting (including, without limitation, rental
concessions to new tenants, repairs, Alterations, legal fees and brokerage
commissions) to satisfy the payment of Rent due under this Lease for any month,
Tenant shall pay Landlord any such deficiency upon demand. Tenant agrees that
Landlord may file suit to recover any sums due Landlord under this Section from
time to time and that such suit or recovery of any amount due Landlord shall not
be any defense to any subsequent action brought for any amount not previously
reduced to judgment in favor of Landlord.

         (iii) Terminate this Lease and Tenant's right of possession of the
Premises, and recover from Tenant, at Landlord's sole and exclusive option,
either (A) the net present value of the Rent due from the date of termination
until the Expiration Date, discounted at the lesser of the Interest Rate as of
the date of termination or a discount rate which equals the interest rate for
U.S. Treasury Securities having a maturity corresponding to the scheduled
Expiration Date of this Lease, plus two hundred (200) basis points, or (B)
"Indemnity Payments" which shall mean an amount equal to the Base Rent and
Additional Rent and other payments provided for in this Lease which would have
become due and owing thereunder from time to time during the unexpired Lease
Term after the effective date of the termination, but for such termination, less
the Base Rent and Additional Rent and other payments, if any, actually collected
by Landlord and allocable to the Premises. If Landlord elects to pursue
Indemnity Payments in lieu of the amount recoverable under clause (A) of this
subparagraph (iii), above, Tenant shall, on demand, make Indemnity Payments
monthly, and Landlord may sue for all Indemnity Payments at any time after they
accrue, either monthly, or at less frequent intervals. Tenant further agrees
that Landlord may bring suit for Indemnity Payments at or after the end of the
Lease Term as originally contemplated under this Lease, and Tenant agrees that,
in such event, Landlord's cause of action to recover the Indemnity Payments
shall be deemed to have accrued on the last day of the Lease Term as originally
contemplated.

         (iv) Re-enter and repossess the Premises and remove all persons and
effects therefrom, by summary proceeding, ejectment or other legal action, but
only with applicable legal process. Landlord shall have no liability by reason
of any such re-entry, repossession or removal.

         (v) Recover from Tenant, to the extent permitted under the laws of the
Commonwealth of Virginia, the value and/or cost of all concessions made to or
for the benefit of Tenant under this Lease.

         (vi) Recover from Tenant, to the extent not already recovered pursuant
to the preceding subparagraphs of this Section 22.2, any other amount which is
necessary to compensate Landlord for economic damages sustained by Landlord and
caused by Tenant's failure to perform Tenant's obligations under this Lease,
including, without limitation, any costs or expenses incurred by Landlord: (i)
in retaking possession of the Premises; (ii) in maintaining, repairing,
preserving, restoring, replacing, cleaning, altering or rehabilitating the
Premises or a portion thereof, including expenses incurred in performing such
acts in connection with any reletting to a new tenant or tenants; (iii) for
leasing commissions incurred in connection with any reletting to a new tenant or
tenants; and/or (iv) for any other commercially reasonable costs incurred by
Landlord in reletting the Premises.

         22.3 Rights Upon Possession. If Landlord takes possession pursuant to
this Article, with or without this Lease, Landlord may, at its option, enter
into the Premises, remove Tenant's Alterations, signs, personal property,
equipment and other evidences of tenancy, and store them at Tenant's risk and
expense or dispose of them as Landlord may see fit, and take and hold possession
of the Premises; provided, however, that if Landlord elects to take possession
only without terminating this Lease, such entry and possession shall not
terminate this Lease or release Tenant or any Guarantor, in whole or in part,
from the obligation to pay the Rent reserved 

                                       22



<PAGE>   23

hereunder for the full Term or from any other obligation under this Lease or any
guaranty thereof. Landlord will not exercise self help without applicable legal
process in order to recover possession of the Premises.

         22.4 No Waiver. If Landlord shall institute proceedings against Tenant
and a compromise or settlement thereof shall be made, the same shall not
constitute a waiver of any other covenant, condition or agreement herein
contained, nor of any of Landlord's rights hereunder. No waiver by Landlord of
any breach shall operate as a waiver of such covenant, condition or agreement,
or operate as a waiver of such covenant, condition or agreement itself, or of
any subsequent breach thereof. No payment of Rent by Tenant or acceptance of
Rent by Landlord shall operate as a waiver of any breach or default by Tenant
under this Lease. No payment by Tenant or receipt by Landlord of a lesser than
the monthly installment of Rent herein stipulated shall be deemed to be other
than a payment on account of the earliest unpaid Rent, nor shall any endorsement
or statement on any check or communication accompanying a check for the 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 to pursue any other remedy provided in this Lease. No re-entry by
Landlord, and no acceptance by Landlord of keys from Tenant, shall be considered
an acceptance of a surrender of the Lease.

         22.5 Right of Landlord to Cure Tenant's Default. If an Event of Default
shall occur, then Landlord may (but shall not be obligated to) make such payment
or do such act to cure the Event of Default, and charge the amount of the
expense thereof, together with interest thereon at the interest Rate, to Tenant.
Such payment shall be due and payable upon demand; however, the making of such
payment or the taking of such action by Landlord shall not be deemed to cure the
Event of Default or to stop Landlord from the pursuit of any remedy to which
Landlord would otherwise be entitled. Any such payment made by Landlord on
Tenant's behalf shall bear interest until paid at the Interest Rate.

         22.6 Late Payment. If Tenant fails to pay any Rent within five (5) days
after such Rent becomes due and payable, Tenant shall pay to Landlord a late
charge of five percent (5%) of the amount of such overdue Rent. In addition, any
such late Rent payment shall bear interest from the date such Rent became due
and payable to the date of payment thereof by Tenant at the Interest Rate. Such
late charge and interest shall be due and payable within two (2) days after
written demand from Landlord.

         22.7 Landlord Default. If Landlord shall fail to keep or perform any of
its obligations under this Lease, which failure on Landlord's part continues for
fifteen (15) business days after Landlord's receipt of a written notice from
Tenant specifying the failure (or, in the case of any such failure which cannot
with due diligence be cured within fifteen (15) business days, within such
additional period, if any, as may be reasonably required by Landlord to cure
such failure with due diligence provided Landlord commences such cure within the
initial fifteen (15) business day period and thereafter diligently pursues same
to completion), and without waiving or releasing Landlord from any obligation or
limiting any other remedy available to Tenant at law or in equity by virtue of
such uncured default, Tenant shall have the right (but not the obligation) to
make such payment or perform such obligation and all sums so paid by Tenant and
all necessary and incidental costs and expenses, including reasonable attorney's
fees paid to independent legal counsel, incurred by Tenant in making such
payment or performing such obligation, together with interest thereon at the
Interest Rate from the date of payment, shall be paid by Landlord to Tenant on
demand, and if not so paid by Landlord, Tenant shall have the right to pursue
any legal remedies available to it to collect payment. Except as specifically
provided in this Lease to the contrary, in no event shall Tenant be entitled to
offset any sums due and owing from Landlord to Tenant against any Rent or
Additional Rent thereafter payable under this Lease. This Section 22.7 shall not
modify any rights or remedies of Tenant expressly established under Section 12.1
or any of the other provisions of this Lease.

                                   ARTICLE 23
                                    MORTGAGES

         23.1 Subordination. Subject to Section 23.4, below, this Lease is and
shall be subject and subordinate to all ground or underlying leases and to any
first Mortgage(s) which may now or hereafter affect such lease or the 


                                       23


<PAGE>   24

Land and to all renewals, modifications, consolidations, replacements and
extensions thereof. Tenant shall execute promptly any instrument that Landlord
or any first Mortgagee may reasonably request confirming such subordination.
Notwithstanding the foregoing, before any foreclosure sale under a Mortgage, the
Mortgagee shall have the right to subordinate the Mortgage to this Lease, and,
in the event of a foreclosure, this Lease may continue in full force and effect
and Tenant shall attorn to and recognize as its landlord the purchaser of
Landlord's interest under this Lease. Tenant shall, upon the request of a
Mortgagee or purchaser at foreclosure, execute, acknowledge and deliver any
instrument that as for its purpose and effect the subordination of the lien of
any Mortgage to this Lease or Tenant's attornment to such Purchaser, provided
that the holder of such mortgage or other lien on the Building or Property shall
contemporaneously execute an "SNDA" with Tenant meeting the requirements of
Section 23.4, below.

         23.2 Mortgagee Protection. Tenant agrees to give any Mortgagee by
certified mail, return receipt requested, a copy of any notice of default served
upon Landlord, provided that before such notice Tenant has been notified in
writing of the address of such Mortgagee. Tenant further agrees that if Landlord
shall have failed to cure such default within the time provided for in this
Lease, then Mortgagee shall have an additional thirty (30) days within which to
cure such default; provided, however, that (i) if such default cannot be
reasonably cured within that time, then such Mortgagee shall have such
additional time as may be necessary to cure such default so long as Mortgagee
has commenced and is diligently pursuing the remedies necessary to cure such
default (including, without limitation, the commencement of foreclosure
proceedings, if necessary), in which event this Lease shall not be terminated or
Rent abated while such remedies are being so diligently pursued, and (ii) the
foregoing additional cure right shall not affect or delay Tenant's right to
abatement or reduction of rent pursuant to Section 18.3, above, to the extent
applicable under the terms of such Section. In the event of the sale of the Land
or the Building, by foreclosure or deed in lieu thereof, the Mortgagee or
purchaser at such sale shall be responsible for the return of the Security
Deposit only to the extent that such Mortgagee or purchaser actually received
the Security Deposit.

         23.3 Modification Due to Financing. If, in connection with obtaining
construction or permanent financing for the Premises, the Building or the Land,
any lender (or Mortgagee) shall request reasonable modifications of this Lease
as a condition to such financing, Tenant shall promptly execute a modification
of this Lease, provided such modifications do not materially increase the
financial obligations of Tenant hereunder or materially adversely affect the
leasehold interest hereby created or Tenant's reasonable use and enjoyment of
the Premises. Tenant and any Guarantor shall each, prior to execution and
throughout the Term, upon request from time to time, provide such financial
information and documentation about itself to Landlord or Mortgagee as may be
requested.

         23.4 Non-Disturbance Agreement. Landlord agrees to obtain a
Subordination, Non-Disturbance and Attornment Agreement from any future
mortgagee for the Building in a form to be negotiated between Landlord, Tenant
and the applicable mortgagee or deed of trust holder, using such mortgagee's
standard form, and approval of which by Tenant and Landlord shall not be
unreasonably withheld, conditioned or delayed (as reasonably approved by
Landlord, Tenant and such mortgagee, an "SNDA"), providing, inter alia, (i) for
the subordination of this Lease to such mortgage, (ii) for the attornment of
Tenant to Landlord's successor in title, and (iii) that, as long as Tenant is
not in Default hereunder beyond any applicable notice and cure period, Tenant's
right of possession and other leasehold rights shall not be disturbed in the
event of a foreclosure of such mortgage. Upon obtaining such SNDA from such
mortgagee, Tenant agrees to promptly execute and deliver such SNDA to Landlord.
In addition, within thirty (30) days after the date of final execution and
delivery of this Lease by both Landlord and Tenant, Landlord, Tenant and
Landlord's existing mortgagee shall execute and deliver an SNDA which is
consistent with the provisions of this Section 23.4. Landlord and Tenant agree
that the SNDA attached as Exhibit E hereto is mutually acceptable to them.

                                   ARTICLE 24
                             SURRENDER; HOLDING OVER

         24.1 Surrender of the Premises. Tenant shall peaceably surrender the
Premises to Landlord on the Expiration Date or earlier termination of this
Lease, in broom-clean condition and in as good condition as when 

                                       24


<PAGE>   25

Tenant took possession, including, without limitation, the repair of any damage
to the Premises caused by the removal of any of Tenant's personal property or
trade fixtures from the Premises, except for reasonable wear and tear and loss
by fire or other casualty not caused by Tenant or its Agents. Any of Tenant's
personal property left on or in the Premises, the Building or the Common Area
after the Expiration Date or earlier termination of this Lease shall be deemed
to be abandoned, and, at Landlord's option, title shall pass to Landlord under
this Lease.

         24.2 Holding Over. In the event that Tenant shall not immediately
surrender the Premises to Landlord on the Expiration Date or earlier termination
of this Lease, Tenant shall be deemed to be a month to month tenant upon all of
the terms and provisions of this Lease, except the monthly Base Rent shall be
125% of the monthly Base Rent in effect during the last month of the Term during
the first month thereof and 150% of the monthly Base Rent in effect during the
last month of the Term for any period thereafter. Notwithstanding the foregoing,
if Tenant shall hold over after the Expiration Date or earlier termination of
this Lease, and Landlord shall desire to regain possession of the Premises
immediately, then Landlord may forthwith re-enter and take possession of the
Premises. Tenant shall indemnify Landlord against all liabilities and damages
sustained by Landlord by reason of such retention of possession, provided Tenant
will not be responsible for losses or claims suffered by Landlord on account of
any delay in delivery of the Premises or any part thereof to a successor tenant
unless either (i) Landlord notifies Tenant prior to the Lease expiration date
that Landlord has entered into a Lease or letter of intent with a prospective
replacement Tenant which requires Landlord to perform construction within the
Premises, or otherwise tender possession thereof to a new tenant, promptly after
the Lease expiration date, and Tenant still fails to surrender possession of the
Premises on or before the Lease expiration date, or (ii) Tenant fails to vacate
the Premises promptly after Landlord notifies Tenant that it requires possession
of the Premises in order to deliver possession thereof to a replacement tenant
to the extent such notice is given after the scheduled Lease expiration date or
in connection with any other permitted termination of this Lease.

                                   ARTICLE 25
                                 QUIET ENJOYMENT

         Landlord covenants that if Tenant shall pay Rent and perform all of the
terms and conditions of this Lease to be performed by Tenant, Tenant shall
during the Term peaceably and quietly occupy and enjoy possession of the
Premises without molestation or hindrance by Landlord or any party claiming
through or under Landlord, subject to the provisions of this Lease and any
Mortgage to which this Lease is subordinate and easements, conditions and
restrictions of record affecting the Land.


                                   ARTICLE 26
                TENANT'S COVENANTS REGARDING HAZARDOUS MATERIALS

         26.1 Definition. As used in this Lease, the term "Hazardous Material"
means any flammable items, explosives, radioactive materials, hazardous or toxic
substances, material or waste or related materials, including any substances
defined as or included in the definition of "hazardous substances," "hazardous
wastes," "infectious wastes," "hazardous materials" or "toxic substances" now or
subsequently regulated under any federal, state or local laws, regulations or
ordinances including, without limitation, oil, petroleum-based products, paints,
solvents, lead, cyanide, DDT, printing inks, acids, pesticides, ammonia
compounds and other chemical products, asbestos, PCBs and similar compounds, and
including any different products and materials which are subsequently found to
have adverse effects on the environment or the health and safety of persons.

         26.2 General Prohibition. Tenant shall not cause or permit any
Hazardous Material to be generated, produced, brought upon, used, stored,
treated, discharged, released, spilled or disposed of on, in, under or about the
Premises, the Building or the Land by Tenant or its Agents, affiliates,
sublessees or assignees without the prior written consent of Landlord. Landlord
shall be entitled to take into account such factors or facts as Landlord may in
its good faith business judgment determine to be relevant in determining whether
to grant, condition or withhold consent to Tenant's proposed activity with
respect to Hazardous Material and Tenant shall 


                                       25

<PAGE>   26

indemnify, defend and hold Landlord and its Agents harmless from any and all
actions (including, without limitation, remedial or enforcement actions of any
kind, administrative or judicial proceedings, and orders or judgments arising
out of or resulting therefrom), costs, claims, damages (including, without
limitation, punitive damages), expenses (including, without limitation,
attorneys', consultants' and experts' fees, court costs and amounts paid in
settlement of any claims or actions), fines, forfeitures or other civil,
administrative or criminal penalties, injunctive or other relief (whether or not
based upon personal or bodily injury, property damage, contamination of, or
adverse effects upon, the environment, water tables or natural resources),
liabilities or losses payable to any third party and arising from a breach of
this prohibition by Tenant, its Agents, affiliates, sublessees or assignees. In
no event, however, shall Landlord be required to consent to the installation or
use of any storage tanks in, on or under the Premises, the Building or the Land.
If Landlord consents to the generation, production, use, storage, treatment or
disposal of Hazardous Materials in or about the Premises by Tenant, its Agents,
affiliates, sublessees or assignees, then, in addition to any other requirements
or conditions that Landlord may impose in connection with such consent, (1)
Tenant promptly shall deliver to Landlord copies of all permits, approvals,
filings, and reports reflecting the legal and proper generation, production,
use, storage, treatment or disposal of all Hazardous Materials generated, used,
stored, treated or removed from the Premises, the Building and the Land and,
upon Landlord's request, copies of all hazardous waste manifests relating
thereto, and (2) upon expiration or earlier termination of this Lease, Tenant
shall cause all Hazardous Materials arising out of or related to the use or
occupancy of the Premises by Tenant or its Agents, affiliates, sublessees or
assignees to be removed from the Premises, the Building and the Land and
transported for use, storage or disposal in accordance with all applicable laws,
regulations and ordinances and Tenant shall provide Landlord with evidence
reasonably satisfactory to Landlord of the same.

         26.3 Notice. In the event that Hazardous Materials are discovered upon,
in, or under the Premises, the Building or the Land and any governmental agency
or entity having jurisdiction over the Premises, the Building or the Land
requires the removal of such Hazardous Materials, Tenant shall be responsible
for removing those Hazardous Materials arising out of or related to the use or
occupancy of the Premises by Tenant or its Agents, affiliates, sublessees or
assignees but not those of its predecessors. Notwithstanding the foregoing,
Tenant shall not take any remedial action in or about the Premises, the Building
or the Land, nor enter into any settlement agreement, consent decree or other
compromise with respect to any claims relating to any Hazardous Material in any
way connected with the Premises, the Building or the Land without first
notifying Landlord of Tenant's intention to do so and affording Landlord the
opportunity to appear, intervene or otherwise appropriately assert and protect
Landlord's interest with respect thereto. Tenant immediately shall notify
Landlord in writing of: (i) any spill, release, discharge or disposal of any
Hazardous Material in, on or under the Premises, the Building, the Land or any
portion thereof, (ii) any enforcement, cleanup, removal or other governmental or
regulatory action instituted, contemplated or threatened (if Tenant has notice
thereof) pursuant to any Hazardous Materials Laws; (iii) any claim made or
threatened by any person against Tenant, the Premises, the Building or the Land
relating to damage, contribution, cost recovery, compensation, loss or injury
resulting from or claimed to result from any Hazardous Materials; and (iv) any
reports made to any environmental agency or entity arising out of or in
connection with any Hazardous Materials in, on, under or about or removed from
the Premises, the Building or the Land, including any complaints, notices,
warnings, reports or asserted violations in connection therewith. Tenant also
shall supply to Landlord as promptly as possible, and in any event within five
(5) business days after Tenant first receives or sends the same, copies of all
claims, reports, complaints, notices, warnings or asserted violations relating
in any way to the Premises, the Building, the Land or Tenant's use or occupancy
thereof.

         26.4 Medical Wastes.

         (i) To the extent Tenant's Permitted Use of the Premises in any way
involves the handling, use, disposal and/ or processing of medical waste,
including but not limited to (A) human or animal tissue, blood, urine and/or
other bodily fluids, materials and/or biological byproducts, and (B) medical
supplies (such as, but not limited to, used syringes, gauze and bandages, etc.)
(hereinafter, collectively, "Medical Waste"), Tenant shall be solely responsible
for the proper use, storage, removal and disposal of same from the Premises. 
Tenant shall 


                                       26


<PAGE>   27



make arrangements with a reputable and duly licensed disposal company or
contractor for the proper disposal of Medical Waste, in accordance with lawfully
permitted methods of Medical Waste disposal, and Tenant shall pay all costs
associated with such disposal. Tenant shall not place any Medical Waste in any
of the Common Areas without Landlord's prior consent. In its processing, use and
disposal of Medical Waste, Tenant shall comply with all applicable laws,
regulations and ordinances governing the generation, use, processing and
disposal thereof, as well as any additional requirements which Landlord may
reasonably establish from time to time by written notice to Tenant.

         (ii) Tenant shall bear all costs and liability resulting from the
presence of Medical Waste which is caused or permitted by Tenant (or Tenant's
agents, employees or contractors) in, on or under the Premises, the Building or
The Project (including without limitation, liability arising from the
transportation of Medical Waste to or from the Premises, Building and/or Project
and the cleanup of Medical Waste therefrom.)

         (iii) Tenant shall indemnify Landlord, its agents, employees or
contractors, from and against any and all claims, losses, damages, liabilities
and expenses (including reasonable attorneys' fees) incurred, suffered or
sustained by (or brought against) Landlord arising from or associated with: (i)
the acts or omissions of Tenant, its agents, employees or contractors with
respect to the presence of Medical Waste at the Premises, the Building and/or
The Project (including without limitation, liability arising from the
transportation of Medical Waste to or from the Premises or the cleanup of
Medical Waste); (ii) the storage and disposal of Medical Waste by Tenant, its
agents, employees or contractors; or (iii) Tenant's operations at the Premises
related to the processing, use and disposal of Medical Waste. This
indemnification shall survive termination of the Lease.

         26.5 Landlord's Covenants Regarding Hazardous Materials.

                  26.5.1 Landlord represents to Tenant that, to the Landlord's
knowledge, based upon the Preliminary Environmental Assessment of the Property
performed on Landlord's behalf by Engineering Consulting Services, Ltd. ("ECS")
and dated September 18, 1997 (the "Existing Report"), the Property does not
contain any Hazardous Materials except as noted in the Existing Report. Landlord
has provided Tenant prior to Lease execution with a complete copy of the
Existing Report, which Tenant acknowledges having received. If, during the Lease
Term, (a) Landlord is notified of or introduces Hazardous Materials in, on or
under the Property, or there is a violation of the requirements of any
applicable environmental laws which is not the responsibility of Tenant under
Sections 26.2 or 26.3, above, or (b) there is Hazardous Materials contamination
in, on or under the Property which is not the responsibility of Tenant pursuant
to Sections 26.2 and 26.3, above, then as between Landlord and Tenant, Landlord
shall be solely responsible for making a prompt assessment of the scope and
nature of the problem, and for taking remedial action, in conjunction (if
appropriate) with applicable federal, state or local authorities; and in the
event the presence of such Hazardous Materials was caused by Landlord, or its
authorized agents, employees or contractors, or pre-existed Tenant's occupancy
of the Premises, or was not caused by Tenant, its agents, employees,
contractors, sublessees, assignees, transferees or (while within the Premises)
invitees, Landlord shall be responsible for the cost to remediate any such
contamination and/or correct any such violation. The foregoing is without
prejudice to Landlord's right to seek recovery of damages or losses from the
parties at fault in connection with any incident involving the introduction,
presence or disposal of Hazardous Materials within the Land, Building or
Premises. In addition, Landlord shall not cause any Hazardous Material to be
generated, produced, brought upon, used, stored, treated, discharged, released,
spilled or disposed of on, in, under or about the Premises, the Building or the
Land by Landlord or its Agents.

                  26.5.2. Landlord shall indemnify, defend and hold Tenant and
its Agents harmless from any and all actions (including, without limitation,
remedial or enforcement actions of any kind, administrative or judicial
proceedings, and orders or judgments arising out of or resulting therefrom),
costs, claims, damages (including, without limitation, punitive damages),
expenses (including, without limitation, attorneys', consultants' and experts'
fees, court costs and amounts paid in settlement of any claims or actions),
fines, forfeitures or other civil, administrative or criminal penalties,
injunctive or other relief (whether or not based upon personal or bodily 

                                       27
<PAGE>   28

injury, property damage, contamination of, or adverse effects upon, the
environment, water tables or natural resources), liabilities or losses payable
to any third party because of, or arising out of or relating to the violation of
any of Landlord's representations, warranties and covenants under this Section
26.5 by Landlord or its employees, agents or affiliates.

         26.6 Survival. The respective rights and obligations of Landlord and
Tenant under this Article 26 shall survive the expiration or earlier termination
of this Lease without limitation.

                                   ARTICLE 27
                                  CONTINGENCIES

         This Lease and the obligations of the parties hereto are subject to the
execution and delivery by NATIONAL INSURANCE GROUP ("Guarantor") of that certain
Guaranty of Lease attached as Exhibit F hereto and made a part hereof (the
"Guaranty") by this reference. If Guarantor fails to deliver the Guaranty to
Landlord fully executed simultaneous with the final execution and delivery of
this Lease by Tenant, then this Lease shall be void ab initio.

                                   ARTICLE 28
                                  MISCELLANEOUS

         28.1 No Representation by Landlord. Tenant acknowledges that neither
Landlord or its Agents nor any broker has made any representation or promise
with respect to the Premises, the Building, the Land or the Common Area, except
as herein expressly set forth, and no rights, privileges, easements or licenses
are acquired by Tenant except as expressly set forth herein and in Exhibit B.
Except as otherwise set forth herein or in Exhibit B of this Lease, Tenant, by
taking possession of the Premises shall accept the Premises and the Building "AS
IS".

         28.2 No Partnership. Nothing contained in this Lease shall be deemed or
construed to create a partnership or joint venture of or between Landlord and
Tenant, or to create any other relationship between Landlord and Tenant other
than that of landlord and tenant.

         28.3 Brokers. Landlord recognizes Broker(s) as the sole broker(s)
procuring this Lease and shall pay Broker(s) a commission therefor pursuant to a
separate agreement between Broker(s) and Landlord. Landlord and Tenant each
represents and warrants to the other that it has not employed any broker, agent
or finder other than Broker(s) relating to this Lease. Landlord shall indemnify
and hold Tenant harmless, and Tenant shall indemnify and hold Landlord harmless,
from and against any claim for brokerage or other commission arising from or out
of any breach of the indemnitor's representation and warranty.

         28.4 Estoppel Certificate/Financial Information. (a) Tenant shall,
without charge, at any time and from time to time, within ten (10) business days
after request therefor by Landlord, Mortgagee, any purchaser of the Land or the
Building or any other interested person, execute, acknowledge and deliver to
such requesting party a written estoppel certificate certifying, as of the date
of such estoppel certificate, the following: (i) that this Lease is unmodified
and in full force and effect (or if modified, that the Lease is in full force
and effect as modified and setting forth such modifications); (ii) that the Term
has commenced (and setting forth the Commencement Date and Expiration Date);
(iii) that Tenant is presently occupying the Premises; (iv) the amounts of Base
Rent and Additional Rent currently due and payable by Tenant; (v) that any
Alterations required by the Lease to have been made by Landlord have been made
to the satisfaction of Tenant; (vi) that there are no existing set-offs,
charges, liens, claims or defenses against the enforcement of any right
hereunder, including without limitation, Base Rent or Additional Rent (or, if
alleged, specifying the same in detail); (vii) that no Base Rent (except the
first installment thereof) has been paid more than thirty (30) days in advance
of its due date; (viii) that Tenant has no knowledge of any then uncured default
by Landlord of its obligations under this Lease (or, if Tenant has such
knowledge, specifying the same in detail); (ix) that Tenant is not in default;
(x) that the 

                                       28



<PAGE>   29

address to which notices to Tenant should be sent is as set forth in the Lease
(or, if not, specifying the correct address); and (xi) any other certifications
reasonably requested by Landlord. In

         (b) Prior to Lease execution, Tenant shall deliver such financial
statements (including a balance sheet and an income/loss statement) for Tenant's
most recent fiscal year (1997) which Guarantor shall certify to Landlord as
being true and correct in all material respects and prepared in accordance with
generally accepted accounting principles, consistently applied. Within thirty
(30) days after request by Landlord, Tenant shall deliver to Landlord financial
statements of Tenant (including a balance sheet and an income/loss statement)
for its most recently ended fiscal year and interim financial statements for its
most recently ended quarter, in both cases certified by Guarantor as (i) being
true and correct in all material respects, and (ii) prepared in accordance with
generally accepted accounting principles, consistently applied. In addition,
within thirty (30) days after request by Landlord, Tenant shall cause Guarantor
to deliver to Landlord financial statements of Guarantor (including a balance
sheet and an income/loss statement) for its most recently ended fiscal year and
interim financial statements for its most recently ended quarter, in both cases
certified by Guarantor as being true and correct in all material respects, and
accompanied by an opinion of a certified public accountant that such statements
were prepared in accordance with generally accepted accounting principles,
consistently applied. Tenant acknowledges and agrees that (i) during the
continuation of any failure by Tenant to provide any of the financial statements
described in this Section 28.4(b), and (ii) in the event any of financial
information provided by Tenant to Landlord is materially inaccurate or
incomplete, Landlord shall have certain additional rights against Guarantor
pursuant to the terms of the Section 32(b) of the Guaranty.

         28.5 Waiver of July Trial. Tenant hereby waives trial by jury in any
action, proceeding or counterclaim brought by Landlord against Tenant with
respect to any matter whatsoever arising out of or in any way connected with
this Lease, the relationship of Landlord and Tenant hereunder or Tenant's use or
occupancy of the Premises. In the event Landlord commences any proceedings for
nonpayment of Rent, Tenant shall not interpose any non-compulsory counterclaims.
This shall not, however, be construed as a waiver of Tenant's right to assert
such claims in any separate action brought by Tenant.

         28.6 Notices. All notices or other communications hereunder shall be in
writing and personally delivered, delivered by Federal Express or other
regionally or nationally recognized overnight courier, or mailed by certified or
registered mail, return receipt requested, postage prepaid, addressed and sent,
if to Landlord to Landlord's Address specified in Section 1.14 or if to Tenant
to Tenant's Address specified in Section 1.15. All such notices shall be deemed
duly given upon the earlier to occur of actual receipt or refusal of delivery.
Landlord and Tenant may from time to time by written notice to the other
designate another address for receipt of future notices. To the extent is
entitled to a written notice of any failure of performance or default by Tenant
pursuant to Section 22.1 of this Lease, Landlord agrees to provide concurrent
notice of such failure or default to Guarantor, at the notice address set forth
herein.

         28.7 Invalidity of Particular Provisions. If any provisions 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 provision to persons or circumstances other than those to
which it is invalid or unenforceable, shall not be affected thereby, and each
provision of this Lease shall be valid and be enforced to the full extent
permitted by law.

         28.8 Gender and Number. All terms and words used in this Lease,
regardless of the number or gender in which they are used, shall be deemed to
include any other number or gender as the context may require.

         28.9 Benefit and Burden. Subject to the provisions of Article II and
except as otherwise expressly provided, 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, heirs, successors and assigns. Landlord may
freely and fully assign its interest hereunder.


                                       29

<PAGE>   30

         28.10 Entire Agreement. This Lease (which includes the Exhibits and
Rider attached hereto) contains and embodies the entire agreement of the parties
hereto, and no representations, inducements or agreement, oral or otherwise,
between the parties not contained in this Lease shall be of any force or effect.
This Lease (other than the Rules and Regulations, which may be changed from time
to time as provided herein) may not be modified, changed or terminated in whole
or in part in any manner other than by an agreement in writing duly signed by
Landlord and Tenant

         28.11 Authority.

         (i) If Tenant signs as a corporation, the person executing this Lease
on behalf of Tenant hereby represents and warrants that Tenant is a duly formed
and validly existing corporation, in good standing, qualified to do business in
the Commonwealth of Virginia, that the corporation has full power and authority
to enter into this Lease and that he or she is authorized to execute this Lease
on behalf of the corporation.

         (ii) If Tenant signs as a partnership, the person executing this Lease
on behalf of Tenant hereby represents and warrants that Tenant is a duly formed,
validly existing partnership qualified to do business in the Commonwealth of
Virginia, that the partnership has full power and authority to enter into this
Lease, and that he or she is authorized to execute this Lease on behalf of the
partnership.

         28.12 Attorneys' Fees. If, as a result of any default of Landlord or
Tenant in its performance of any of the provisions of this Lease, the other
party uses the services of an attorney in order to secure compliance with such
provisions or recover damages therefor, or to terminate this Lease or evict
Tenant, the non-prevailing party shall reimburse the prevailing party upon
demand for any and all reasonable attorneys' fees and expenses so incurred by
the prevailing party.

         28.13 Interpretation. This Lease is governed by the laws of the
Commonwealth of Virginia.

         28.14 No Personal Liability; Sale. Neither Landlord nor its Agents,
whether disclosed or undisclosed, shall have any personal liability under any
provision of this Lease. In the event of a judgment in favor of Tenant which
remains unpaid, Tenant's right of redress, execution and levy shall be limited
to the equity of Landlord in the Building as described in Article 1 hereof. In
the event that the original Landlord hereunder, or any successor owner of the
Building, shall sell or convey the Building, all liabilities and obligations on
the part of the original Landlord, or such successor owner, under this Lease
accruing after the effective date of transfer or conveyance shall terminate as
of the day of such sale, and all liabilities and obligations on the part of the
Landlord accruing on and after the effective date of transfer or conveyance
shall automatically be binding on the new owner (and the transferor Landlord
shall thereupon be released from such future obligations and liabilities).
Tenant agrees to attorn to such new owner. Any successor to Landlord's interest
shall not be bound by (i) any payment of Base Rent or Additional Rent for more
than one (1) month in advance, except for the payment of the first installment
of First Year Base Rent or (ii) as to any Mortgagee or any purchaser at
foreclosure, any amendment or modification of this Lease made without the
consent of such Mortgagee.

         28.15 Time of the Essence. Time is of the essence as to both Landlord's
and Tenant's obligations contained in this Lease.

         28.16 Force Majeure. Except as hereafter provided, neither Landlord nor
Tenant shall be considered to be in default of an obligation under this Lease
nor liable for loss or damage for failure to perform an obligation (nor shall
the other party be released from any of its obligations under this Lease if the
non-performing party is delayed in performing an obligation), where the
performance of such obligation by the non-performing party is delayed as a
result of event of "Force Majeure" which shall mean any acts of God, strikes,
lockouts, labor difficulties, materials shortages, moratoria, explosions,
sabotage, accidents, riots, civil commotions, acts of war, results of any
warfare or warlike conditions in this or any foreign country, fire or casualty,
unusually inclement 

                                       30


<PAGE>   31

weather, unusual governmental delays (which shall include any County processing
time for the building permit for the Tenant Improvements in excess of forty five
(45) days after submission of construction drawings), unusual and unforeseeable
legal requirements, energy shortages or other causes beyond the reasonable
control of the non-performing party, provided that in no event shall (i)
financial inability be considered an event of Force Majeure, and (ii) in no
event shall Force Majeure excuse the timely performance by any party hereto of
its monetary obligations under this Lease.

         28.17 Headings. Captions and headings are for convenience of reference
only.

         28.18 Memorandum of Lease. Tenant shall, at the request of Landlord,
execute and deliver a memorandum of lease in recordable form. Tenant shall not
record such a memorandum or this Lease without Landlord's consent. In the event
Tenant requests recordation of a memorandum of this Lease, Tenant shall be
obligated to pay all costs, fees and taxes, if any, associated with such
recordation.

         28.19 [Intentionally Deleted]

         28.20 Attorney-in-Fact. If Tenant fails or refuses to execute and
deliver any instrument or certificate required to be delivered by Tenant
hereunder (including, without limitation, any instrument or certificate required
under Article 23 or Section 27.4 hereof) within the time periods required
herein, then Tenant hereby appoints Landlord as its attorney-in-fact with full
power and authority to execute and deliver such instrument or certificate for
and in the name of Tenant

         28.21 Effectiveness. The furnishing of the form of this Lease shall not
constitute an offer and this Lease shall become effective upon and only upon its
execution by and delivery to each party hereto.

                                   ARTICLE 29
                               SPECIAL PROVISIONS

         29.1 Renewal Option(s).

                  29.1.1 Provided Tenant is not in monetary or other material
Default of this Lease beyond any applicable cure periods at the time its rights
hereunder are to be exercised, Tenant shall have the option (each, a "Renewal
Option") to extend the Lease Term for one (1) period of sixty (60) months
(referred to as the "Renewal Term") provided Tenant gives written notice to
Landlord of its election to exercise such Renewal Option (the "Renewal Notice")
not less than six (6) months prior to the expiration of the last day of the
initial Lease Term.

                  29.1.2 All terms and conditions of this Lease, including
without limitation, all provisions governing the payment of Additional Rent,
shall remain in full force and effect during the Renewal Term, except the Base
Rent shall be as set forth in this Section 29.1.

                  29.1.3 The Base Rent payable upon the commencement of the
Renewal Term shall equal the then prevailing market rental rate (including base
rental rate and escalation rate) applicable to renewal terms with respect to
comparable space in comparable buildings in the vicinity of the Project, (the
"Fair Market Rate" or "FMR") at the time of the commencement of the applicable
Renewal Term, determined based upon then existing renewal market conditions
applicable to the leasing of comparable space in comparable buildings in the
vicinity of The Project (taking into consideration all relevant factors,
including use, location, quality, age and location of the applicable building,
the definition of net rentable area and allowances and other concessions
typically given under renewal leases in comparable properties to the Property in
the vicinity of the Project). Further, the Fair Market Rate shall be determined
on a triple-net basis. Landlord and Tenant shall negotiate in good faith and in
accordance with the procedure set forth in Section 29.1.4, below, to determine
the Fair Market Rate which will be applicable during the Renewal Term, with the
goal of concluding such negotiation or triggering a determination of the FMR
using a three-appraiser method (as described in Section 29.1.5, below) within
not more than sixty (60) days after the date of Landlord's receipt of the
Renewal Notice.

                                       31
<PAGE>   32


                  29.1.4 Within ten (10) business days after Landlord receives
Tenant's Renewal Notice exercising the Renewal Option, Landlord will provide
Tenant with a written notice (the "FMR Notice") indicating the base rental rate
and annual escalation rate which Landlord in good faith believes represents the
then current FMR for the Premises. If Tenant is in agreement with the base
rental rate and annual escalation rate stated in the FMR Notice, Tenant shall so
notify Landlord within ten (10) business days after its receipt thereof, in
which case such base rental rate and annual escalation rate shall constitute the
FMR for such Renewal Term within the meaning of this Section 29.1. If Tenant
believes in good faith that the base rental rate and annual escalation rate
stated by Landlord in the FMR Notice are in excess of actual FMR for the
Premises, Tenant shall so notify Landlord in writing prior to the end of the ten
(10) business day period after Tenant received Landlord's FMR Notice, stating in
its response (hereinafter referred to as "Tenant's Counterproposal") the base
rental rate and annual escalation rate which Tenant in good faith believes
represents the then current FMR for the Premises. If Tenant fails to respond to
the Landlord's FMR Notice within such ten (10) business day period, Tenant shall
be deemed to have accepted the base rental rate and annual escalation rate
stated in Landlord's FMR Notice. If Tenant does provide Tenant's Counterproposal
to Landlord in a timely fashion, and Landlord agrees that the base rental rate
and annual escalation rate stated in Tenant's Counterproposal represent the then
current FMR, Landlord shall so notify Tenant within ten (10) business days after
its receipt thereof, in which case such base rental rate and annual escalation
rate shall constitute the FMR for such Renewal Term within the meaning of this
Section 29.1. If Landlord fails to respond to the Tenant's Counterproposal
within ten (10) days after Landlord's receipt of the Tenant's Counterproposal,
or rejects the rental rate and escalation rate stated therein, then the parties
agree to submit the issue of what constitutes the appropriate FMR for the
Premises for the Renewal Term to determination using a "three appraiser method"
as described in Section 29.1.5, below.

                  29.1.5 If the parties submit the issue of what constitutes the
appropriate FMR for the Premises for the Renewal Term to determination using a
"three appraiser method", then the basic rent and annual escalations applicable
during the Renewal Term shall be equal to the FMR and annual escalation rates
determined by a board of three (3) licensed real estate appraisers, one of whom
shall be named by Landlord, one by Tenant, and the two so appointed shall select
the third. Each member of the board of appraisers shall be licensed in the
Commonwealth of Virginia as a real estate appraiser, with a substantial
familiarity in the field of commercial office/flex leasing in the
Chantilly/Dulles area of Fairfax County, Virginia, having no less than ten (10)
years experience in such field, and recognized as ethical and reputable within
the field. Landlord and Tenant agree to make their appointments within five (5)
business days after the earlier to occur of (i) the expiration of the ten (10)
day period after Landlord's receipt of Tenant's Counterproposal, or (ii) the
date Landlord notifies Tenant of its rejection of Tenant's Counterproposal. The
two (2) appraisers selected by Landlord and Tenant shall promptly select a third
appraiser within ten (10) days after the second to be appointed has been
appointed, and each appraiser, within ten (10) days after the third appraiser is
selected, shall submit his or her determination of the said FMR and escalations
(taking into account the provisions of Section 51.3 hereof). If either of the
parties fail to select an appraiser within the aforesaid time periods, such
party's appraiser shall be designated (in compliance with the applicable
criteria set forth above and affiliated with a different company from the other
broker) by an agent of the Fairfax County Board of Realtors in office at such
time; and if the appraisers selected by Landlord and Tenant (or on their behalf
) are unable to reach agreement on the identity of the third appraiser within
the applicable ten (10) day period, then the third appraiser shall be designated
(in compliance with the applicable criteria set forth above) by an agent of the
Fairfax County Board of Realtors in office at such time. The FMR shall be the
average of amount determined by the two appraisers whose determinations are
closest in amount to each other (or if two appraisers reach an identical
determination, the determination of such two appraisers), provided that if the
two (2) most proximate determinations of FMR differ by more than ten percent
(10%), then the determination of FMR by such board of three appraisers shall be
null and void, and Landlord and Tenant shall, within five (5) business days
thereafter, appoint a new board of three different real estate appraisers
meeting the above-stated criteria, who shall convene in accordance with the
procedures and time frames set forth above in order to render a new
determination, as if the first determination had never taken place. After the
Fair Market Rent has been established, the appraisers shall immediately notify
the parties in writing, and such determination shall be conclusive and binding
upon the parties. Landlord and Tenant shall each pay the fee of the appraiser
selected by it, and they shall equally share the payment of the fee of the third
appraiser.


                                       32
<PAGE>   33

         29.2 Roof Rights.

                  29.2.1 Subject to (i) compliance with all rules, regulations,
statutes and codes of any governmental authority having jurisdiction thereover,
(ii) compliance with any covenants, conditions and restrictions applicable to
Dulles Business Park and (iii) subject to Landlord's prior written consent,
which consent shall not be unreasonably withheld, conditioned or delayed, Tenant
shall have the right of access to and the non-exclusive use of the roof of the
Buildings for the installation of a single rooftop satellite communication
device (Tenant's "Roof Use"); provided further that such installation and the
Roof Use shall not void any roof or other warranty applicable to the Building
and that all such installations shall be located and screened in a manner
mutually acceptable to both Landlord and Tenant in their reasonable discretion.

                  29.2.2 If the rate of any insurance carried by Landlord is
increased as a result of Tenant's Roof Use, then Tenant will pay to Landlord
within thirty (30) days after Landlord delivers to Tenant a certified statement
from Landlord's insurance carrier stating that the rate increase was caused by
Tenant's Roof Use, a sum equal to the difference between the original premium
and the increased premium resulting from the Roof Use.

                  29.2.3 Landlord has not made any representations or promises
pertaining to the suitability of the Building's rooftop for the Roof Use.
Tenant, for the purpose of this paragraph and its right to rooftop access
hereunder, accepts the rooftop in its "as is" condition. The foregoing
notwithstanding, Landlord agrees to cooperate with Tenant during the design
phase of the Building (if and to the extent practicable) to design and engineer
an area of the roof to be constructed within which Tenant's Roof Use may be
conducted and which will be suitable for such purpose, provided Tenant provides
appropriate specifications to Landlord during such design process to enable
Landlord to cause the design to accommodate such use.

                  29.2.4 Tenant will obtain prior to installation, any and all
necessary licenses, approvals, permits, etc., necessary for the installation,
maintenance and use of any equipment installed pursuant to this Section 29.2.
Tenant's Roof Use shall not in any way conflict with any applicable law,
statute, ordinance or governmental rules or regulation now in force or which may
hereafter be enacted. The Tenant will, at its sole cost and expense, promptly
comply or ensure that the Building complies with all laws, statutes, ordinances,
governmental rules or regulations, or requirements of any board of fire
insurance underwriters or other similar bodies now or hereafter constituted
relating to or affecting Tenant's Roof Use. Tenant shall indemnify and hold
Landlord harmless from and against any and all loss, cost (including reasonable
attorney's fees incurred in defending Landlord), damage or liability arising out
of any violations of said laws, statutes, ordinances rule or regulations.

                  29.2.5 Tenant's Roof Use shall be exercised: (1) in such
manner as will not create any hazardous condition or interfere with or impair
the operation of the heating, ventilation, air conditioning, plumbing,
electrical, fire protection, life safety, public utilities or other systems or
facilities in the Buildings; (2) in compliance with all applicable laws, codes
and regulations; (3) in such a manner as will not directly or indirectly
interfere with, delay, restrict or impose any expense, work or obligation upon
Landlord in the use or operation of the Buildings; (4) at Tenant's cost,
including the cost of repairing all damage to the Buildings and any personal
injury and/or property damage attributable to the installation, inspection,
adjustment, maintenance, removal or replacement of any equipment or apparatus on
the roofs approved hereunder; and (5) in a manner which will not void or
invalidate any roof warranty then in effect with respect to the roof of the
Building. Tenant's Roof Use shall be used solely in the ordinary course of
Tenant's business operations, and any use of the roof outside of the ordinary
course of Tenant's business operations (such as, but not limited to, subleasing
portions of the roof for profit to third parties, in order for such third
parties to establish communications transmission facilities) shall be subject to
Landlord's consent, which consent shall not be unreasonably withheld, but may be
conditioned, inter alia, upon the payment by Tenant to Landlord of one-half of
any net revenues paid to Tenant in respect thereof.


                                       33

<PAGE>   34

         29.3 UPS/Generator Rights.

                  29.3.1 Subject to (i) compliance with all rules, regulations,
statutes and codes of any governmental authority having jurisdiction thereover,
(ii) compliance with any covenants, conditions and restrictions applicable to
Dulles Business Park, and (iii) subject to Landlord's prior written consent,
which consent shall not be unreasonably withheld, conditioned or delayed, Tenant
shall have the right of access to and the non-exclusive use of a portion of the
ground area immediately appurtenant to the Premises for the installation of
Uninterrupted Power Supply (UPS) equipment and/or standby generators (Tenant's
"Grounds Use"); provided further that such installation and Grounds Use shall be
located and screened in a manner mutually acceptable to both Landlord and Tenant
in their reasonable discretion.

                  29.3.2 If the rate of any insurance carried by Landlord is
increased as a result of Tenant's Grounds Use, then Tenant will pay to Landlord
within thirty (30) days after Landlord delivers to Tenant a certified statement
from Landlord's insurance carrier stating that the rate increase was caused by
Tenant's Grounds Use, a sum equal to the difference between the original premium
and the increased premium resulting from the Grounds Use.

                  29.3.3 Landlord has not made any representations or promises
pertaining to the suitability of the land appurtenant to the Building for the
Grounds Use. Tenant, for the purpose of this paragraph, accepts the applicable
portion of such land area in its "as is" condition. The foregoing
notwithstanding, Landlord agrees to cooperate with Tenant during the design
phase of the Building (to the extent practicable) to design and engineer an area
appurtenant to the Premises within which Tenant's Grounds Use may be conducted
and which will be suitable for such purpose, provided Tenant provides
appropriate specifications to Landlord during such design process to enable
Landlord to cause the design to accommodate such use.

                  29.3.4 Tenant will obtain prior to installation, any and all
necessary licenses, approvals, permits, etc., necessary for the installation,
maintenance and use of any equipment installed pursuant to this Section 29.3.
Tenant's Grounds Use shall not in any way conflict with any applicable law,
statute, ordinance or governmental rules or regulation now in force or which may
hereafter be enacted. The Tenant will, at its sole cost and expense, promptly
comply or ensure that the connection of Tenant's Ground Use to the Premises
complies with all laws, statutes, ordinances, governmental rules or regulations,
or requirements of any board of fire insurance underwriters or other similar
bodies now or hereafter constituted relating to or affecting thereto. Tenant
shall indemnify and hold Landlord harmless from and against any and all loss,
cost (including reasonable attorney's fees incurred in defending Landlord),
damage or liability arising out of any violations of said laws, statutes,
ordinances rule or regulations.

                  29.3.5 Tenant's Grounds Use shall be exercised: (1) in such
manner as will not create any hazardous condition or interfere with or impair
the operation of the heating, ventilation, air conditioning, plumbing,
electrical, fire protection, life safety, public utilities or other systems or
facilities in the Building; (2) in compliance with all applicable laws, codes
and regulations; (3) in such a manner as will not directly or indirectly
interfere with, delay, restrict or impose any expense, work or obligation upon
Landlord in the use or operation of the Building; and (4) at Tenant's cost
(subject to reimbursement from any applicable Improvement Allowance pursuant to
Exhibit B), including the cost of repairing all damage to the Building and any
personal injury and/or property damage attributable to the installation,
inspection, adjustment, maintenance, removal or replacement of any equipment or
apparatus on the roofs approved hereunder. Tenant's Grounds Use shall be used
solely in the ordinary course of Tenant's business operations, and is personal
to Tenant and any party to whom Tenant assigns this Lease or sublets a portion
of the Premises pursuant to Section 11.4 hereof.

         29.4 Tenant's Outdoor Area.

         Subject (i) to governmental approval, (ii) the further provisions of
this Section 29.4, and (iii) to the requirement that the same not adversely
affect truck access and truck turnaround to and from the ECS loading 


                                       34


<PAGE>   35

dock, Landlord agrees that Tenant may install, at its expense (including as part
of the Improvement Allowance to the extent set forth in Exhibit B) a patio with
picnic benches, a basketball backboard and half-court basketball court striping
area (the "Basketball Area") and planters intended to create a landscape buffer
between the exterior area adjacent to the Premises and the exterior area
adjacent to the premises occupied by ECS (the "ECS Premises"), substantially as
depicted in Schedule B-2 of this Lease or as otherwise consented to by Landlord
in its reasonable discretion ("Tenant's Outdoor Area"). Tenant agrees to limit
usage of the Basketball Area to the hours of 12:00 noon through 2:00 p.m. daily,
and after 5:00 p.m., daily, provided Tenant may, but only with the consent of
ECS or its successors in occupancy of the ECS Premises, use the Basketball Area
at such other times as may be approved by such occupant(s) of the ECS Premises.
Tenant, for the purpose of this paragraph, accepts the applicable portion of
such land area in its "as is" condition and agrees not to adversely affect any
storm drainage facilities, utility installations or other facilities serving the
Building located within the affected area in the installation and use of such
area. Such installation shall be considered a part of the Tenant Improvements,
to be performed by Tenant pursuant to Section 6.5(a) of Exhibit B, if installed
as part of the initial construction of Tenant Improvements to the Premises, or
as an Alteration pursuant to Article 13 of this Lease, if installed after the
Substantial Completion of the Tenant Improvements (provided Landlord hereby
evidences its approval of Tenant's Outdoor Area as depicted in Schedule B-2 for
purposes of Article 13). The installation and use of Tenant's Outdoor Area shall
be conducted (1) in such manner as will not create any hazardous condition or
interfere with or impair the operation of the heating, ventilation, air
conditioning, plumbing, electrical, fire protection, life safety, public
utilities or other systems or facilities in the Building; (2) in compliance with
all applicable laws, codes and regulations; (3) at Tenant's cost (subject to
reimbursement from any applicable Improvement Allowance pursuant to Exhibit B),
including the cost of repairing all damage to the Building and any personal
injury and/or property damage attributable to the installation, inspection,
adjustment, maintenance, use, removal or replacement of any equipment or
apparatus therein; and (4) in a manner which will not adversely affect ECS's
truck access and turnaround requirements as determined by ECS in its sole, but
reasonable, judgment. Tenant shall have the right to restrict the use of such
area to its employees and invitees, provided Tenant agrees that the occupant(s)
of the ECS Premises shall have the right of exclusive use of the balance of the
outdoor area adjacent to Tenant's Outdoor Area, including for installation and
use of similar picnic facilities and the like.

         IN WITNESS WHEREOF, Landlord and Tenant have executed this Lease as of
the 8th day of May, 1998.

                                    LANDLORD:

                                    FCP-DULLES BUSINESS PARK I, L.C., a Virginia
                                    limited liability company

                                    By: CRIMSON PARTNERS, L.C., a Virginia
                                    limited liability company


                                    By:   /s/ R. KEVIN DOUGHERTY          (SEAL)
                                          --------------------------------------
                                    Name:  R. Kevin Dougherty 
                                    Title: Managing Member

                                    TENANT:

                                    PINNACLE REAL ESTATE TAX SERVICES, INC., a
                                    Delaware corporation


                                    By:   /s/ DONALD S. GRANT             (SEAL)
                                          --------------------------------------
                                    Title: Donald S. Grant, Vice President -
                                           Facilities



                                       35
<PAGE>   36



                                   EXHIBIT A-1
                             (Plan Showing Premises)







                                       36
<PAGE>   37




                                   EXHIBIT A-2
                        (Plat Showing Land and Building)







                                       37

<PAGE>   38


                                    EXHIBIT B
                                 WORK AGREEMENT

         This Work Agreement is attached to and made a part of that certain Deed
of Lease dated as of May 8, 1998 (the "Lease"), between FCP-DULLES BUSINESS PARK
I, L.C., a Virginia limited liability company ("Landlord"), and PINNACLE REAL
ESTATE TAX SERVICES, INC. ("Tenant"). The terms used in this Exhibit that are
defined in the Lease shall have the same meanings as provided in the Lease.

1. General.

         1.1      Purpose. This Agreement sets forth the terms and conditions
                  governing the design, permitting and construction of all
                  tenant improvements to be installed in the Premises in
                  accordance with the Approved Plans and any change orders
                  thereto ("Tenant Improvements").

         1.2      Tenant's Representative. Tenant acknowledges that Tenant has
                  appointed Donald Grant as its authorized representative
                  ("Tenant's Representative") with full power and authority to
                  bind Tenant for all actions taken with regard to the Tenant
                  Improvements. To the extent any actions and decisions were
                  taken by Tenant's Representative with regard to the Tenant
                  Improvements prior to the execution of this Work Agreement,
                  such actions are hereby ratified by Tenant. Landlord shall not
                  be obligated to respond to or act upon any plan, drawing,
                  change order or approval or other matter relating to the
                  Tenant Improvements until it has been executed by Tenant's
                  Representative. Neither Tenant nor Tenant's Representative
                  shall be authorized to direct Landlord's general contractor
                  with respect to the Tenant Improvements. In the event that the
                  Landlord's general contractor performs any work for Tenant
                  under a separate written contract or written instruction from
                  Tenant or Tenant's Representative, then Landlord shall have no
                  liability for the cost of such work, the cost of corrective
                  work required as a result of such work, any delay that may
                  result from such work, or any other problem in connection with
                  such work.

2. Work and Materials

         2.1      Tenant Improvements. Landlord, at Tenant's expense, shall
                  construct the Premises in accordance with the Tenant Plans (as
                  defined below). The Tenant Plans shall be conclusive as to the
                  entire scope of work to be performed by Landlord with respect
                  to the Tenant Improvements.

         2.2      Improvement Allowance. Landlord agrees to credit Tenant with
                  an allowance not to exceed Twenty-Five Dollars ($25.00) per
                  rentable square foot which is equal to a total of Eight
                  Hundred Thirty-Four Thousand, Seventy-five and 00/100 Dollars
                  ($834,075) which shall be applicable to the cost of all Tenant
                  Improvements ("Improvement Allowance"). Except as specifically
                  provided below with regard to Landlord's agreement to fund
                  certain "Excess Costs" subject to Tenant's obligation to make
                  certain monthly payments in respect thereof, Landlord's total
                  financial obligation with respect to the purchase,
                  construction, and installation of the Tenant Improvements or
                  any other improvements to the Premises shall be limited solely
                  to the Improvement Allowance (and any financial obligations
                  which flow from any breach of Landlord's obligation to perform
                  punch list work hereunder), and except as specifically set
                  forth in this Lease, Tenant shall be solely responsible for
                  any and all such costs in excess of the Improvement Allowance.
                  Landlord agrees that Tenant may allocate up to $5,000 of the
                  Improvement Allowance to pay for demolition of certain asphalt
                  areas of the parking lot adjacent to the Premises and the
                  installation of landscaping therein, as approved by Landlord
                  in its reasonable discretion, which for purposes of this
                  provision shall be deemed to constitute Tenant Improvements
                  under the Lease.

                                       38

<PAGE>   39


                  For purposes of this Exhibit B, the cost of all Tenant
                  Improvements shall mean any and all costs associated with the
                  design and construction of the Tenant Improvements (exclusive
                  of Base Building Improvements, as hereafter provided),
                  including the cost of all labor, services and materials
                  necessary to design, permit, inspect and construct the
                  Premises. Without limitation, the foregoing shall include all
                  architectural and engineering fees and costs, utility fees,
                  tap fees, systems development charges, fixture fees, fees and
                  costs for preparation of mechanical, electrical and plumbing
                  (MEP) drawings, inspection fees, construction management fees
                  provided for herein, and contractor profits, whether any of
                  the foregoing were furnished to, or by, Landlord, and whether
                  any of the foregoing were paid by Landlord prior to or after
                  Lease execution or prior to or after the commencement of
                  construction of the Tenant Improvements.

         2.3      Bidding. The Tenant Improvements shall be competitively bid in
                  the following manner:

                           (a) Landlord shall cause the bidding package for the
                  Tenant Improvements to be submitted to at least three (3)
                  qualified general contractors, all of whom shall be
                  financially sound and able to complete the Tenant Improvements
                  within the time frames contemplated by the bidding materials.
                  Tenant shall have the right to designate one (1) qualified
                  general contractor to bid on the Tenant Improvements, which
                  general contractor shall be financially sound and able to
                  complete the Tenant Improvements within the time frames
                  contemplated by the bidding materials, and otherwise subject
                  to Landlord's reasonable approval. The bidding shall require
                  all contractors to provide for a construction schedule
                  consistent with the terms of this Lease, without special
                  additional charge or increased cost for overtime.

                           (b) All contractors shall submit their bids directly
                  to Landlord, who will review and analyze all bids submitted,
                  and Landlord shall format all the bids for review by Tenant;
                  and Landlord will prepare a bid format (the "Bid Format")
                  which lists all bids received, which Landlord agrees to
                  provide to Tenant within seven (7) days after receipt of the
                  last bid. The Bid Format is intended to make each bid
                  submitted comparable in scope so that the bid prices reflected
                  are based on substantially equal services and materials. In
                  the absence of a substantial basis for selecting otherwise,
                  Landlord agrees to accept the lowest bid reflected within the
                  Bid Format as long as the low bidder is able to meet any
                  timing requirements applicable hereunder.

                  Once the bid selection process has been completed, Landlord
                  will supply Tenant with its estimate of the total costs which
                  Landlord estimates will be applicable to the performance of
                  the Tenant Improvements (hereinafter referred to as the "Cost
                  Estimate"). Landlord agree to require all bidders to provide
                  as part of its bid (i) a warranty for the Tenant Improvements
                  for a period of one (1) year from Substantial Completion, to
                  the effect that all work will be performed in a good and
                  workmanlike manner, in accordance with the Approved Plans (as
                  modified by any written change orders), using new materials
                  and free from defects in materials and workmanship, and (ii) a
                  list of all "long lead items", that is, items specified by
                  Tenant in the Approved Plans which involve delayed delivery to
                  an extent that would cause delay in meeting the general
                  contractor's schedule for Substantial Completion and thereby
                  constitute an event of "Tenant Delay" under Section 6.3(f) of
                  this Exhibit B, below. In addition, each general contractor
                  will be asked to include in its bid as an optional item the
                  additional cost for obtaining and/or providing warranties on
                  certain building systems and equipment (to be designated by
                  Tenant in Tenant's Space Plan) which extend beyond one (1)
                  year (as also designated by Tenant).

         2.4      Excess Costs. In the event the successful bid received
                  pursuant to Section 2.3, above, causes (or is likely to cause)
                  the total expenses associated with construction of the Tenant
                  Improvements

                                       39


<PAGE>   40

                  to exceed the Improvement Allowance, Landlord shall promptly
                  notify Tenant of the amount (or Landlord's best estimate of
                  the amount) of the overage ("Excess Cost"). Tenant, within
                  five (5) days after receipt of Landlord's notice, shall notify
                  Landlord as to whether Tenant (i) wishes Landlord to commence
                  construction of the Tenant Improvements; or (ii) wishes to
                  re-design the Premises so as to reduce the Excess Cost. In the
                  event Tenant wishes to redesign the Premises so as to reduce
                  the Excess Cost:

                           (a)      said redesign shall be performed at Tenant's
                                    sole expense;

                           (b)      said redesign shall be completed and
                                    submitted to Landlord within ten (10) days
                                    after Tenant's notice to Landlord that it
                                    wishes to redesign the Premises so as to
                                    reduce the Excess Cost;

                           (c)      said redesign shall not delay the Lease
                                    Commencement Date and any delay associated
                                    therewith shall constitute a Tenant Delay
                                    hereunder; and

                           (d)      said redesign shall be conclusive and
                                    binding on Tenant.

                  In the event Tenant elects not to redesign the Premises or to
                  partially redesign the Premises, any remaining Excess Cost
                  shall be paid for by Tenant as hereinafter provided. Tenant
                  shall have the right to amortize up to $5.00 per square foot
                  of Excess Costs over the initial ten (10) year Lease Term at a
                  twelve percent (12%) annual interest rate, which amount shall
                  be payable by Tenant to Landlord in equal monthly installments
                  of principal and interest which monthly installments shall be
                  paid (as additional rent hereunder) at the same time as
                  monthly payments of Base Rent otherwise stated to be due from
                  Tenant to Landlord under the Lease are due and payable from
                  Tenant to Landlord (but which monthly installments of
                  principal and interest shall not be subject to annual 3%
                  escalations as are otherwise applicable to Base Rent). Tenant
                  shall notify Landlord of such election within ten (10) days
                  after the Landlord provides Tenant with the Cost Estimate, or,
                  if applicable, within ten (10) days after the above-described
                  value engineering process has been completed and a revised
                  Cost Estimate prepared, failing which Tenant shall be deemed
                  to have elected not to amortize any Excess Cost. In the event
                  Tenant elects to amortize any Excess Cost, Landlord and Tenant
                  shall execute an amendment to the Lease verifying the amount
                  of the Excess Cost and Tenant's payment schedule therefor. If
                  the total Excess Cost exceeds $5.00 per square foot, or if
                  Tenant elects not to amortize all or any portion of the Excess
                  Cost (or if Tenant refuses to execute an amendment to the
                  Lease which correctly establishes the amount of the Excess
                  Cost and Tenant's payment schedule therefor within ten (10)
                  business days after the amendment is presented by Landlord to
                  Tenant for execution), then the portion of the Excess Cost not
                  amortized (up to the whole) or the entire Excess Cost if
                  Tenant fails to execute a correctly prepared amendment within
                  the aforesaid time period, shall be paid by Tenant as follows:
                  One third (1/3) on or before the date of commencement of
                  construction of the Tenant Improvements, one-third (1/3)
                  within thirty (30) days after construction of the Tenant
                  Improvements has been fifty percent (50%) completed (as
                  certified by the general contractor), and one-third (1/3) upon
                  substantial completion of the Tenant Improvements and in all
                  events on or before the Commencement Date.

                  Within thirty (30) days after completion of Landlord's Work,
                  Landlord shall provide Tenant with a written statement (the
                  "Final Statement") of the actual total cost of the Tenant
                  Improvements (hereafter, the "Actual Cost"). If the Final
                  Statement indicates that the Actual Cost was less than the
                  Improvement Allowance, Tenant shall be entitled to apply the
                  unused portion thereof (up to a maximum of $5.00 per rentable
                  square foot) (i) to pay for Tenant's satellite dish described
                  in Section 29.2, Tenant's above-ground generator described in
                  Section 29.3, Tenant's out-of-pocket moving expenses, or any
                  other items permitted to be installed by Tenant as part of the
                  Tenant Improvements pursuant to Section 6.5(a), below, (ii) to
                  pay for costs associated with the installation of Tenant's
                  Outdoor Area pursuant to Section 29.4 of the

                                       40


<PAGE>   41

                  Lease, or (iii) as a credit against the first payments of Base
                  Rent becoming due under this Lease. If the Final Statement
                  indicates that the Actual Cost exceeded the sum of the
                  Improvement Allowance and the Excess Costs previously
                  disclosed and charged to Tenant pursuant to this Section 2.3
                  (collectively, the "Total Tenant Credit"), then Tenant shall
                  pay Landlord an amount equal to the difference between the
                  Actual Cost and the Total Tenant Credit within ten (10)
                  business days after receipt of Landlord's statement.

         2.5      Base Building Improvements. Landlord agrees to construct, at
                  Landlord's sole expense, and in a diligent manner intended to
                  achieve substantial completion thereof consistent with the
                  timing requirements of this Lease, the shell of the Building
                  and certain base building improvements thereto, as described
                  in the plans referenced in Schedule B-1 attached hereto and
                  made a part hereof by this reference, including the
                  landscaping and parking areas reflected within such plans
                  (hereinafter referred to as the "Base Building Improvements"
                  and which shall include up to $2,000 in trees and bushes in
                  any asphalt cut-out areas adjacent to Tenant's windows which
                  Tenant elects to perform pursuant to Section 2.2, above). All
                  work to the interior of the Premises which is not reflected as
                  part of the Base Building Improvements within Schedule B-1
                  shall be deemed to be Tenant Improvements within the meaning
                  of this Exhibit B.

         2.6      Construction. Promptly after the general contractor has been
                  selected and a construction contract executed (including any
                  value engineering performed pursuant to Section 2.4, above)
                  and a building permit has been received by Landlord for
                  construction of the Tenant Improvements, Landlord shall cause
                  its general contractor to commence and diligently pursue the
                  completion of installation of the Tenant Improvements in
                  accordance with the Approved Plans (and any written change
                  orders thereto). Landlord shall supervise such work (as
                  provided in Section 4, below) and shall use commercially
                  reasonable efforts to achieve Substantial Completion of the
                  Tenant Improvements within the timing requirements of this
                  Exhibit B. However, except as provided in Section 6.6 of this
                  Exhibit B, below, Landlord shall have no liability to Tenant
                  for any delay in commencement, construction or completion of
                  the Tenant Improvements.

3. Design.

         3.1 Design of Tenant Improvements.

                  3.1.1 Space Plan. Landlord and Tenant have not reached
                  agreement on a space plan/layout of the Premises as of the
                  date of execution of this Lease. Promptly after Lease
                  execution (and in no event later than May 11, 1998), Tenant
                  shall cause its architect, Rusty Shaw of Architecture, Inc. of
                  Reston, Virginia to prepare and submit to Landlord for
                  approval (which shall not be unreasonably withheld) a space
                  plan for the entire Premises, defining the scope of the Tenant
                  Improvements. Promptly thereafter, Landlord shall indicate to
                  Tenant whether it has any objections to Tenant's proposed
                  space plan. If Landlord fails to provide a written objection
                  within four (4) days after the date Landlord receives the
                  applicable submission from Tenant's architect, the same shall
                  be deemed to have been approved by Landlord. If there are any
                  such objections, the parties will work together expeditiously
                  and in good faith to resolve such objections as quickly as
                  possible (and in all events no later than May 15, 1998). Any
                  delay by Tenant in provision or completion of a space plan
                  beyond the time frames described above which causes delay in
                  commencement or completion of the Workable Shell Structure or
                  Tenant Improvements shall constitute a Tenant Delay for all
                  purposes of this Lease. As approved by Landlord, Tenant's
                  space plan shall be referred to herein as the " Space Plan".
                  "CDS" shall mean and refer to the all plans for construction
                  of the Tenant Improvements, including construction drawings
                  and specifications and MEP plans to the extent required for
                  the permitting of all leasehold construction contemplated by
                  this Lease.



  
                                       41


<PAGE>   42

                           3.1.2 Time Periods. In connection with the design of
                  Tenant Improvements to the Premises, the following maximum
                  time periods shall be allowed for the following matters:
<TABLE>
<CAPTION>

                                   Matter                      Time Period
                                   ------                      -----------

<S>                                                         <C> 
                  (a) Submission by Tenant to Landlord      (a) May 11, 1998
                      of Tenant's proposed Space Plan


                  (b) Final approval of Space Plan          (b) May 15, 1998

                  (c) Tenant provides Landlord              (c) June 30, 1998
                      with an initial draft of the
                      CDS.

                  (d) Landlord gives Tenant its             (d) Five (5) working
                      approval of CD's by signing               days after 
                      and dating CD's.                          receipt of CD's 
                                                                from Tenant
</TABLE>

                  Once the Lease has been fully executed, Landlord and Tenant
                  intend for each deadline expressed in this Work Agreement to
                  bind the parties even if such deadline passes before the date
                  the Lease is executed.

         3.2      Approvals by Landlord. All Tenant Plans shall be subject to
                  Landlord's prior approval, which shall not be unreasonably
                  withheld, except that Landlord shall have complete discretion
                  with regard to granting or withholding approval of any Tenant
                  Plans to the extent they materially and adversely affect the
                  Building's structure or would be visible from the exterior of
                  the Building or any Common Area within the Building. Any
                  changes, additions or modifications that Tenant desires to
                  make to the Tenant Plans also shall be subject to Landlord's
                  prior written approval, which shall not be unreasonably
                  withheld except as provided above for Building structure or
                  appearance impact.

4. Construction and Construction Management.

         4.1      Construction. After approval of the CD's, Landlord shall
                  administer the construction of the Tenant Improvements in
                  accordance with the approved CD's and approved change orders.
                  All Tenant Improvements shall be constructed by or under the
                  supervision of Landlord's general contractor with the
                  exception of those items constructed by Tenant's contractors
                  or vendors (which shall, unless otherwise set forth herein, be
                  limited to installation of telephone equipment, cabling,
                  specialized office equipment wiring and other items permitted
                  to be installed by Tenant pursuant to Section 6.5(a) of the
                  Lease).

         4.2      Construction Management. Landlord may act as or employ the
                  services of a construction manager to oversee the performance
                  of the general contractor performing the Tenant Improvements.
                  A Construction Management fee equal to Twenty Thousand Dollars
                  ($20,000.00) shall be paid to Landlord or such construction
                  manager from the Improvement Allowance in respect of such
                  services.

5.       Change Orders. If Tenant requests any change or addition to the work or
         materials to be provided by Landlord pursuant to this Exhibit after
         Tenant's and Landlord's approval of the Construction Drawings


                                       42



                                                                            
<PAGE>   43

         and Specifications and Tenant's acceptance of the Cost Estimate,
         Landlord shall respond to Tenant's request for consent as soon as
         possible, but in no event later than three (3) working days after it
         being made. If Landlord approves such request, Landlord shall as soon
         as practicable after such approval notify Tenant of the cost of such
         change order and the delay in Substantial Completion of the Premises,
         if any, due to the change order which would be Tenant's sole
         responsibility. All additional expenses attributable to any change
         order requested by Tenant and approved by Landlord (net of any savings
         realized therefrom), whether or not such change order relates to
         improvements paid for under the Tenant Improvements, shall be payable
         along with a five percent (5%) overhead and administrative fee to
         Landlord by Tenant upon approval by Tenant of the change order cost
         and/or delay, if any.

6.       Substantial Completion.

         6.1      General. Landlord shall use reasonable and diligent efforts to
                  Substantially Complete (as defined below) the Tenant
                  Improvements on or before October 1, 1998, but neither the
                  validity of this Lease nor the obligations of Tenant under
                  this Lease shall be affected by a failure to Substantially
                  Complete the Premises by such date, and Tenant shall have no
                  claim against Landlord because of Landlord's failure to
                  Substantially Complete the Premises on the date originally
                  fixed therefor. Landlord shall communicate with Tenant on a
                  regular basis regarding the progress of construction and the
                  status of completion relative to the projected date of
                  Substantial Completion, and will provide Tenant with not less
                  than thirty (30) days prior written notice of the date upon
                  which Landlord estimates that it will achieve substantial
                  completion of the Tenant Improvements once Landlord is able to
                  estimate a specific date with reasonable certainty.

         6.2      Substantial Completion. "Substantial Completion" of the
                  Premises shall be conclusively deemed to have occurred as soon
                  as (i) the Tenant Improvements to be installed by Landlord
                  pursuant to this Work Agreement has been constructed in
                  accordance with the Tenant Plans approved change orders and
                  the Premises are ready to be utilized for general office
                  purposes, as certified by architect, and (ii) it is lawful for
                  Tenant to commence Tenant's Move-In and business operations
                  within the Premises, assuming all Tenant Work and furniture,
                  equipment and property installations to be made by Tenant are
                  in compliance with all applicable legal requirements. The
                  issuance of a temporary certificate of occupancy or
                  non-residential use permit by the proper governmental entity
                  shall be required for Substantial Completion, except to the
                  extent the same is denied due to the acts or omissions of
                  Tenant or Tenant's Agents. To the extent granted, a temporary
                  certificate of occupancy or non-residential use permit by the
                  proper governmental entity shall be deemed conclusive evidence
                  that Substantial Completion has occurred. Notwithstanding the
                  above, the Premises shall be considered Substantially Complete
                  and ready to be utilized for their intended purpose even
                  though (a) there remain to be completed in the Premises
                  certain long lead items, (b) there remain to be completed in
                  the Premises certain punch list items reasonably acceptable to
                  Landlord and Tenant, including but not limited to minor or
                  insubstantial details of construction, decoration or
                  mechanical adjustment, the lack of completion of which will
                  not materially interfere with Tenant's permitted use of the
                  Premises, and/or (c) there is a delay in the Substantial
                  Completion of the Premises due to a "Tenant Delay" as defined
                  below.

         6.3      Tenant Delays. The following items shall be referred to
                  individually as, and shall constitute for all purposes of this
                  Lease, a "Tenant Delay":

                  (a)      Tenant's failure to comply with any of the deadlines
                           specified in this Work Agreement; or

                  (b)      Tenant's request for changes or additions to the
                           Tenant Improvements subsequent to the date of
                           Landlord's approval of the CDS; or

                                       43

<PAGE>   44

                  (c)      Tenant's failure to pay when due any amounts required
                           pursuant to this Work Agreement; or

                  (d)      The performance of any work by any person or firm
                           employed or retained by Tenant; or

                  (e)      Tenant's request for materials, finishes or
                           installations which are not available as needed to
                           meet the general contractor's schedule for
                           Substantial Completion, but only to the extent
                           identified by the general contractor as part of the
                           bidding process as set forth in Section 2.4, above,
                           or occurring in connection with a change order
                           requested by Tenant pursuant hereto (and identified
                           as part of the change order approval process); or

                  (f)      Tenant's or Tenant's agent, including Tenant's
                           contractors vendors, and Representative's
                           interference with the general contractor's schedule;
                           or

                  (g)      Any delay occasioned by Tenant's Early Work.

                  In the event of any delay in the construction of the Building
                  or any Tenant Improvements therein caused by Tenant Delay, the
                  same shall not result in any delay in the Commencement Date of
                  this Lease, even if the Substantial Completion of the Tenant
                  Improvements was delayed beyond the Commencement Date set
                  forth in Article 1 of the Lease, and in such event, the
                  Commencement Date shall be the date Tenant's Architect
                  reasonably estimates that the Tenant Improvements would have
                  been Substantially Completed but for such Tenant Delay
                  (provided that if Landlord disputes the date so estimated by
                  Tenant's Architect, and such dispute is not voluntarily
                  resolved by Landlord and Tenant within ten (10) business days
                  after Landlord's notifies Tenant of the existence of such
                  dispute, the parties agree to submit the matter in controversy
                  to binding arbitration (on an expedited basis) in accordance
                  with the commercial arbitration rules of the American
                  Arbitration Association.

                  The foregoing notwithstanding, Landlord agrees that (i) the
                  occurrence of any event or circumstance described in any of
                  clauses (a) through (g) of this Section 6.3 which does not
                  actually result in delay to the schedule for the planning,
                  design or construction of the Tenant Improvements shall not be
                  deemed a Tenant Delay (e.g., if an event or circumstance of
                  the type described in any of clauses (a) through (g) of this
                  Section 6.3 occurs at the same time as a contractor delay in
                  construction, and the delay reasonably attributable thereto
                  does not extend beyond the concurrent contractor delay, the
                  same shall not constitute a Tenant Delay to such extent).
                  Landlord and Tenant shall each notify the other within three
                  (3) business days after such party obtains knowledge of the
                  occurrence of any delay attributable to the other party, or to
                  any event of force majeure within the meaning of this Lease.

         6.4      Punch List. Prior to delivery of possession of the Premises to
                  Tenant, Landlord's architect shall prepare a preliminary punch
                  list in writing for Landlord and Tenant's review and Landlord
                  and Tenant shall examine the Premises and shall agree on a
                  final "punch list" which shall specify the items of work that
                  require correction, repair or replacement. Tenant shall
                  approve such punch list in writing within two (2) working days
                  of the walk-through.

         6.5      Early Work/Tenant's Move-In.

                                    (a) Section 7 of this Exhibit B to the
                  contrary notwithstanding, Tenant shall be given access to the
                  Premises prior to the substantial completion of the Tenant
                  Improvements, as more fully set forth below, so that Tenant
                  may perform the installation of phone and data wiring and
                  cabling, a special computer room floor, a halon fire
                  protection system, 

                                       44


<PAGE>   45

                  supplementary HVAC units for Tenant's computer room and
                  enhancements to the security systems serving the Premises, and
                  other similar specialized equipment installations therein. Any
                  such work in the Premises prior to the date Landlord achieves
                  Substantial Completion of the Tenant Improvements is herein
                  referred to as "Early Work", and Tenant's entries into the
                  Premises prior to such date shall be strictly limited as
                  hereinafter set forth Landlord and Tenant agree that the
                  performance of any Early Work shall be in accordance with this
                  Paragraph 6.5.

                                    (b) Any entry into the Premises prior to
                  Substantial Completion of the Tenant Improvements and/or the
                  Commencement Date (including without limitation any entry by
                  Tenant for Early Work) shall be subject to all of the terms
                  and conditions of the Lease, except that, other than as a
                  result of entries for purposes of actual occupancy and/or the
                  conduct of Tenant's business (including commencement of
                  business operations), Tenant shall not be required to pay Base
                  Rent, Tenant's Share of Expense Increases and/or increases in
                  Taxes and/or any other additional rent. In addition: (i) any
                  such entry by the Tenant, its agents, employees or contractors
                  (any and all of which to be referred to hereinafter as
                  "Tenant's Personnel") shall be subject to the insurance
                  requirements of Landlord's contractor (which shall provide
                  such requirements to Tenant within five (5) business days
                  after Tenant requests the same in writing); (ii) Tenant's
                  Early Work shall comply with any reasonable scheduling
                  requirements of Landlord's contractor and/or Landlord's
                  construction manager, and Tenant shall request permission to
                  enter the Premises in writing, specifying the requested date,
                  time of entry, and which items of Early Work Tenant intends to
                  perform, at least three (3) business days prior to any such
                  entry, and Landlord's contractor and/or Landlord's
                  construction manager shall respond promptly to such request,
                  in accordance with the scheduling restrictions and
                  requirements set forth hereinbelow; (iii) Tenant's Personnel
                  shall not be permitted to enter the Premises prior to the
                  Substantial Completion of the Tenant Improvements to perform
                  any Early Work unless and until Tenant receives permission
                  from Landlord's contractor or Landlord's construction manager
                  for such entry; (iv) in no event shall any Early Work delay
                  the Substantial Completion of the Tenant Improvements (and if
                  Tenant's Personnel cause any such delay, the same shall
                  constitute a "Tenant Delay" hereunder); and (v) Tenant shall
                  bear the full risk of loss for any materials, equipment, or
                  other property which Tenant's Personnel bring into the
                  Building or the Premises in connection with any Early Work,
                  which shall be at Tenant's sole risk, and Landlord shall not
                  have any liability therefor. Landlord agrees to cause its
                  contractor and construction manager to cooperate in good faith
                  with Tenant to accommodate Tenant's requested entry dates,
                  subject to the terms of this Section 6.5 and the reasonable
                  requirements of such contractor in order to complete the
                  construction of the Tenant Improvements in an orderly and
                  timely fashion.

                                    (c) Only Tenant or Tenant's Personnel will
                  enter the Premises to perform the Early Work. Tenant or such
                  authorized individual(s) performing the Early Work on behalf
                  of Tenant will check in with Landlord's construction manager
                  upon entering the Premises and prior to commencing any Early
                  Work.

                                    (d) Subject to Tenant's compliance with all
                  applicable legal requirements associated therewith, Landlord
                  also agrees that, between the date of Substantial Completion
                  of the Tenant Improvements and the Commencement Date (as such
                  terms are defined in the Lease), Tenant shall have the right
                  to move its furniture, equipment and personal property into
                  the Premises ("Tenant's Move-In") without the same being
                  deemed, by itself, to constitute the commencement of business
                  operations within the Premises by Tenant (provided that if
                  Tenant does in fact commence business operations from all or
                  any part of the Premises prior to the first Monday after the
                  date of Substantial Completion of the Tenant Improvements, the
                  provisions of Article 4 of the Lease shall apply with respect
                  to the establishment of such date as the Commencement Date).
                  With regard to Tenant's Move-In, Tenant agrees (i) that


                                       45


<PAGE>   46

                  Tenant's Move-In shall be at Tenant's sole risk and expense,
                  and shall be subject to all of the terms and conditions of
                  this Lease, except the obligation to pay Base Rent or
                  Additional Rent, (ii) the timing and scope of Tenant's Move-In
                  shall be coordinated with Landlord's property manager and
                  general contractor and shall be conducted to as to permit the
                  orderly progress of any punch list work required to be
                  performed by Landlord and its general contractor, and (iii)
                  any delay in the completion of the construction of the Tenant
                  Improvements occasioned by Tenant's Move-In shall constitute a
                  "Tenant Delay" for all purposes of this Lease.

         6.6      Penalty for Delayed Delivery. Landlord agrees that, in the
                  event Landlord fails to achieve Substantial Completion of the
                  Tenant Improvements for the Premises on or before November 15,
                  1998, which date shall be extended one (1) day for each day of
                  delay in the commencement or completion of Landlord's
                  construction of the Tenant Improvements caused by or resulting
                  from any Tenant Delay or Force Majeure (as so extended, such
                  date is herein referred to as the "Penalty Date"), Tenant
                  shall be entitled, in addition to deferral of the Commencement
                  Date pursuant to Article 4 of the Lease, to a credit against
                  Base Rent due hereunder in an amount equal to one (1) day of
                  Base Rent (calculated on a per diem basis for the first month
                  of the Term) for each day elapsing between the Penalty Date
                  and the date upon which Landlord achieves Substantial
                  Completion of the Tenant Improvements for the Premises. The
                  foregoing shall constitute Landlord's sole liability for
                  damages in the event of any delay in the Substantial
                  Completion of the Tenant Improvements past October 1, 1998.

7.       Possession by Tenant. Except as provided in Section 6.5, above, with
         respect to Tenant's Early Work and Tenant's Move-In, the taking of
         possession of the Premises by Tenant shall constitute an acknowledgment
         by Tenant that the Premises are in good condition and that all work and
         materials provided by Landlord are satisfactory except as to any latent
         defects discovered within the first (1st) lease year of the Term or
         items contained in the punch list prepared as provided in Paragraph
         6.4. Landlord agrees to correct and complete any such items outlined in
         the punch list as soon as practicable, and, subject to Force Majeure
         and Tenant Delay, within thirty (30) days after the Commencement Date.

         IN WITNESS WHEREOF, Landlord and Tenant have executed this Work
Agreement as of the 8th day of May, 1998.

                          LANDLORD:

                          FCP-DULLES BUSINESS PARK I, L.C., a Virginia
                          limited liability company

                          By: CRIMSON PARTNERS, L.C., a Virginia limited
                              liability company


                          By: /s/ R. KEVIN DOUGHERTY
                              ----------------------------------------(SEAL)
                          Name: R. Kevin Dougherty
                          Title:   Managing Member

                          TENANT:

                          PINNACLE REAL ESTATE TAX SERVICES, INC., a Delaware
                          corporation


                          By: /s/  DONALD S. GRANT                    (SEAL)
                                   -----------------------------------------
                                   Donald S. Grant, Vice President - 
                                   Facilities




                                       46
<PAGE>   47

                                  SCHEDULE B-1

Description of Base Building Improvements

Base building shell currently being constructed per Fairfax County Building
Permit 97199B1200, as described by specification sections 02 through 16, dated
July 15, 1997, as prepared by Donnally, Lederer & Vujcic, Associates (formerly
Richard Donnally Associates) and drawings as follows:
<TABLE>
<CAPTION>
Drawing Number              Date/Revision
--------------              -------------
<S>                         <C>  
 A-1                            7/15/97
 A-2                            10/7/97
 A-3                            10/7/97
 A-4                            10/7/97
 A-5                            10/7/97
 A-6                            10/7/97
 A-7                            10/7/97
 A-8                            10/7/97
 A-9                            10/7/97
 A-10                           10/7/97
 A-11                           10/7/97
 A-12                           10/7/97
 S 1                            10/7/97
 S 2                            10/7/97
 S 3                            10/7/97
 S 4                            10/7/97
 S 5                            10/7/97
 S 6                            10/7/97
 S-7                            10/7/97
 M-1                            7/15/97
 M-2                            7/15/97
 P-1                            12/1/97
 P-2                            12/1/97
*P-3                            12/1/97
 E-1                            12/1/97
 E-2                            12/1/97
 E-3                            12/1/97
 E-4                            12/1/97

</TABLE>

*   Excluding the Water Loop shown on Drawing Number P-3 which was installed
    during Building Constructio9n, but will be included in the Tenant
    Imporovement Alowance.l




<PAGE>   48

                                  SCHEDULE B-2



                                  [FLOOR PLAN]



<PAGE>   49


                                    EXHIBIT C

         To the Lease Agreement dated as of May 8, 1998 between FCP-DULLES
BUSINESS PARK I, L.C., a Virginia limited liability company ("Landlord") and
PINNACLE REAL ESTATE TAX SERVICES, INC., a Delaware corporation ("Tenant").

                  Rules and Regulations - Wright I Building/Dulles Business Park

         The following rules and regulations have been formulated for the safety
and well-being of all the tenants of the Building and become effective upon
occupancy. Strict adherence to these rules and regulations is necessary to
guarantee that each and every tenant will enjoy a safe and unannoyed occupancy
in the Building. Any repeated or continuing violation of these rules and
regulations by Tenant after notice from Landlord, shall be sufficient cause for
termination of this Lease at the option of Landlord.

         Landlord may, upon request by any tenant, waive the compliance by such
tenant of any of the following rules and regulations provided that (i) no waiver
shall be effective unless signed by Landlord or Landlord's authorized agent;
(ii) any such waiver shall not relieve such tenant from the obligation to comply
with such rule or regulation in the future unless expressly consented to by
Landlord, and (iii) no waiver granted to any tenant shall relieve any other
tenant from the obligation of complying with the foregoing rules and regulations
unless such other tenant has received a similar waiver in writing from Landlord.

         1. The sidewalks, entrances, passages, courts, vestibules, or
stairways, or other parts of the Building not occupied by any tenant shall not
be constructed or encumbered by any tenant or used for any purpose other than
ingress and egress to and from any tenant's Premises. Landlord shall have the
right to control and operate the public portions of the Building, and the
facilities furnished for the common use of the tenants, in such manner as
Landlord deems best for the benefit of the tenants generally. No tenant shall
permit the visit to its Premises of persons in such numbers or under such
conditions as to interfere with the use and enjoyment by other tenants of the
entrances, and other public portions or facilities of the Building.

         2. No signs, awnings or other projections shall be attached to the
outside walls of any building without the prior written consent of Landlord. No
drapes, blinds, shades or screens shall be attached to or hung in, or used in
connection with, any window or door of the Premises, without the prior consent
of Landlord. Such signs, awnings, projections, curtains, blinds, screens or
other fixtures must be of a quality, type, design and color, and attached in the
manner approved by Landlord.

         3. No show cases or other articles shall be put in front of or affixed
to any part of the exterior of the Building, nor placed in any interior Common
Area without the prior written consent of Landlord.

         4. The water and wash closets and other plumbing fixtures shall not be
used for any purpose other than those for which they were constructed, and no
sweepings, rubbish, rags, or other substances shall be thrown therein. All
damages resulting from any misuse of the fixtures shall be born by the tenant
who, or whose servants, employees, agents, visitors, or licensees, shall have
caused the same.

         5. There shall be no marking, painting, drilling into or in anyway
defacing any part of the Project, Premises or the Building. No boring, cutting
or stringing or wires shall be permitted. No tenant shall construct, maintain,
use or operate within its Premises or elsewhere within or on the outside of the
Building, any electrical devices, wiring or apparatus in connection with a loud
speaker system or other sound system.

         6. No animals, birds, pets of any kind shall be brought into or kept in
or about the Premises, and no cooking shall be done or permitted by any tenant
on its Premises except for a tenant's employee's own use. 

                                       47


<PAGE>   50

No tenant shall cause or permit any unusual or objectionable odors to be
produced or permeate from its Premises.

         7. No tenant shall make, or permit to be made, any unseemly or
disturbing noises or disturb or interfere with occupants of this or any
neighboring building or Premises or with any person having business with such
occupants. No tenant shall throw anything out of the doors or windows or down
the corridors or stairs.

         8. No inflammable, combustible, or explosive fluid, chemical or
radioactive substance shall be brought or kept upon the Premises.

         9. No additional locks or bolts of any kind shall be placed upon any of
the doors, or windows, by any tenant, nor shall any changes be made in existing
locks or the mechanism thereof without prior approval from Landlord. Each tenant
shall, upon termination of its tenancy, restore to Landlord all keys of stores,
offices, storage, and toilet rooms either furnished to, or otherwise procured
by, such tenant, and in the event of the loss of any keys so furnished such
tenant shall pay to Landlord the cost of replacement thereof.

         10. All removals, or the carrying in or out of any safes, freight,
furniture or bulky matter of any description must take place during the hours
which Landlord or its Agent may determine from time to time. Landlord reserves
the right to inspect all freight to be brought into the Premises and to exclude
from the Premises all freight which violates any of these Rules and Regulations
or the Lease of which these Rules and Regulations are a part.

         11. Any person employed by any tenant to do janitorial work within its
premises must obtain Landlord's consent and such person shall, while in the
Building and outside of the Premises, comply with all instructions issued by the
superintendent of the Building. No tenant shall engage or pay any employees on
its Premises, except those actually working for such tenant on its Premises.

         12. No tenant shall purchase spring water, ice, coffee, tea, soft
drinks, towels, or other like service, from any company or persons whose
repeated violations of these Regulations have caused, in Landlord's opinion, a
hazard or nuisance to the Building and/or its occupants.

         13. Landlord reserves the right to exclude from the Building at all
times any person who is not known or does not properly identify himself to the
Building management. Each tenant shall be responsible for all persons for whom
he authorizes entry into or exit out of the Building and shall be liable to
Landlord for all acts of such persons.

         14. The Premises shall not be used for lodging or sleeping or for any
immoral or illegal purpose.

         15. No tenant shall occupy or permit any portion of its Premises to be
used or occupied for the possession, storage, manufacture, or sale of liquor,
narcotics, tobacco in any form. No tenant shall engage or pay any employees on
its Premises, except those actually working for such Tenant on said Premises,
nor advertise for laborers giving an address at said Premises.

         16. Landlord's employees shall not perform any work for Tenant or do
anything outside of their regular duties, unless under special instruction from
the management of the Building.

         17. Canvassing, soliciting, and peddling on the Premises is prohibited
and each Tenant shall cooperate to prevent the same.

         18. No water cooler, plumbing or electrical fixtures shall be installed
by any Tenant without the prior written consent of Landlord.

                                       48

<PAGE>   51

         19. There shall not be used in any space, or in the public halls of the
Building, either by any Tenant or by jobbers or others in the delivery or
receipt of merchandise, any hand trucks, except those equipped with rubber tires
and side guards.

         20. Tenant shall not overload the floors or exceed the maximum floor
weight limits of the Premises.

         21. If Landlord designates a certain portion of parking area for
employee or visitor parking, Tenant covenants that it will require its employees
to park in such area to the extent of spaces available. Landlord shall not be
responsible for enforcing Tenant's parking rights against any third parties.

         22. Tenant agrees to conduct any vehicle or machine repair, painting,
or similar work only inside the Premises.

         23. Tenant agrees not to operate any machinery in the Premises which
may cause vibration or damage to the Premises; not to use a loudspeaker which
can be heard outside the Premises, or to extend curb service to customers.


                                       49
<PAGE>   52

                                    EXHIBIT D

                       DECLARATION BY LANDLORD AND TENANT
                    AS TO DATE OF DELIVERY AND ACCEPTANCE OF
                    POSSESSION, LEASE COMMENCEMENT DATE, ETC.


         THIS DECLARATION is hereby attached to and made a part of the Deed of
Lease dated as of May 8, 1998 (the "Lease"), between FCP-DULLES BUSINESS PARK I,
L.C., a Virginia limited liability company ("Landlord") and PINNACLE REAL ESTATE
TAX SERVICES, INC., a Delaware corporation ("Tenant"). All terms used in this
Declaration have the same meaning as they have in the Lease.

         (i) Landlord and Tenant do hereby declare that possession of the
Premises was accepted by Tenant on ___________________;

         (ii) As of the date hereof, the Lease is in full force and effect, and
Landlord has fulfilled all of its obligations under the Lease required to be
fulfilled by Landlord on or prior to said date (punch list items excepted);

         (iii) The Lease Commencement Date is hereby established to be
___________________; and

         (iv) The Lease Expiration Date is hereby established to
be___________________ unless the Lease is sooner terminated pursuant to any
provision thereof.

                             LANDLORD:

                             FCP-DULLES BUSINESS PARK I, L.C., a Virginia
                             limited liability company

                             By: CRIMSON PARTNERS, L.C., a Virginia limited
                                 liability company


                             By:                                         (SEAL)
                                 ----------------------------------------
                             Name:  R. Kevin Dougherty
                             Title: Managing Member

                             TENANT:

                             PINNACLE REAL ESTATE TAX SERVICES, INC., a Delaware
                             corporation


                             By:                                         (SEAL)
                                 ----------------------------------------------
                                 Donald S. Grant, Vice President - Facilities


                                       50
<PAGE>   53


                                    EXHIBIT E

                                  FORM OF SNDA

                        SUBORDINATION, NONDISTURBANCE AND
                              ATTORNMENT AGREEMENT

         THIS AGREEMENT made this day of , 199 , between
____________________________, a ____________________ (hereinafter called
"Lender"), ________, a (herein after called "Tenant"), and FCP-DULLES BUSINESS
PARK I, L.C., a Virginia limited liability company (said landlord and its
successors and assigns occupying the position of landlord under the Lease
hereinafter called "Landlord").

                          W I T N E S S E T H   T H A T :

         WHEREAS, Lender is the owner and holder of a Deed of Trust, Mortgage
and Security Agreement (hereinafter called the "Security Instrument"), recorded
in Fairfax County, Virginia covering the real improvements thereon (hereinafter
collectively called the "Mortgaged Premises") securing the payment of the
promissory note in the stated principal amount of $__________ payable to the
order of Lender.

         WHEREAS, Tenant is the tenant under Lease Agreement (hereinafter called
the "Lease") dated _____, made by Landlord, covering certain property
(hereinafter called the "Demised Premises") consisting of a part of the
Mortgaged Premises; and

         WHEREAS, Tenant and Lender desire to confirm their understanding with
respect to the Lease and the Security Instrument;

         NOW, THEREFORE, in consideration of the mutual covenants and agreements
herein contained, Lender and Tenant hereby agree and covenant as follows:

         1. Subordination. The Lease now is, and shall at all times and for all
purposes continue to be, subject and subordinate, in each and every respect, to
the Security Instrument, with the provisions of the Security Instrument
controlling in all respects over the provisions of the Lease, it being
understood and agreed that the foregoing subordination shall apply to any and
all increases, renewals, modifications, extensions, substitutions, replacements
and/or consolidations of the loan evidenced by the Security Instrument.

         2. Non-Disturbance. So long as (i) Tenant is not in default (beyond any
period given Tenant to cure such default) in the payment of rent or additional
rent or in the performance of any of the other terms, covenants or conditions of
the Lease on Tenant's part to be performed, (ii) the Lease is in full force and
effect according to its original terms, or with such amendments or modifications
as Lender shall have approved, and (iii) Tenant attorns to Lender or a purchaser
of the Mortgaged Premises as provided in Paragraph 3, then (a) Tenant's
possession, occupancy, use and quiet enjoyment of the Demised Premises under the
Lease, or any extensions or renewals thereof or acquisition of additional space
which may be effected in accordance with any option therefor in the Lease, shall
not be terminated, disturbed, diminished or interfered with by Lender in the
exercise of any of its rights under the Security Instrument, and (b) Lender will
not join Tenant as a party defendant in any action or proceeding for the purpose
of terminating Tenant's interest and estate under the Lease because of any
default under the Security Instrument.

         3. Attornment. If Lender shall become the owner of the Mortgaged
Premises or the Mortgaged Premises shall be sold by reason of non-judicial or
judicial foreclosure of other proceedings brought to enforce the Security
Instrument of the Mortgaged Premises shall be conveyed by deed in lieu of
foreclosure, the Lease shall continue in 


                                       51


<PAGE>   54

full force and effect as a direct Lease between Lender or other purchaser of the
Mortgaged Premises, who shall succeed to the rights and duties of Landlord, and
Tenant shall attorn to Lender or such purchaser, as the case be, upon such
occurrence and shall recognize Lender or such purchaser, as the case may be, as
the Landlord under the Lease. Such attornment shall be effective and
self-operative without the execution of any further instrument on the part of
any of the parties hereto. Tenant agrees, however, to execute and deliver at any
time and from time to time, upon the request of Landlord or of any holder (s) of
any of the indebtedness or other obligations secured by the Security Instrument
or any such purchaser, any instrument or certificate which, in the sole
reasonable judgment of the requesting party, is necessary to or appropriate, in
connection with any such foreclosure or deed in lieu of foreclosure or
otherwise, to evidence such attornment. Tenant hereby 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 or election to terminate or otherwise adversely
affect the Lease and the obligations of Tenant thereunder as a result of any
such foreclosure or deed in lieu of foreclosure.

         4. Obligations and Remedies. If Lender shall become the owner of the
Mortgaged Premises or the Mortgaged Premises shall be sold by reason of
non-judicial or judicial foreclosure or other proceedings brought to enforce the
Security Instrument or the Mortgaged Premises shall be conveyed by deed in lieu
of foreclosure, Lender of other purchaser of the Mortgaged Premises, as the case
may be, shall have the same remedies by entry, action or otherwise in the event
of any default by Tenant (beyond any period given Tenant to cure such default)
in the payment of rent or additional rent or in the performance of any of the
other terms, covenants and conditions of the Lease on Tenant's part to be
performed that Landlord had or would have had if Lender or such purchaser had
not succeeded to the interest of Landlord. Upon attornment by Tenant as provided
herein, Lender or such purchaser shall be bound to Tenant under all the terms,
covenants and conditions of the Lease and Tenant shall have the same remedies
against Lender or such purchaser for the breach of agreement contained in the
Lease that Tenant might have had under the Least against Landlord if Lender or
such purchaser had not succeeded to the interest of Landlord; provided however,
that Lender or such purchaser shall not be liable or bound to Tenant:

         (a) for any act or omission of any prior landlord (including Landlord);
provided, however, nothing contained herein shall be deemed to be waiver of
Tenant's rights or remedies in the event such default is not cured by Lender or
such purchaser after Lender acquires the Mortgaged Premises, or

         (b) for any offsets or defenses which the Tenant might be entitled to
assert against Landlord arising prior to the date Lender takes possession of
Landlord's interest in the Lease or becomes a mortgagee in possession, subject
to Tenant's continued right of offset for any default by Landlord which remains
uncured provided notice of such default has been provided to Lender in
accordance with the provisions this Agreement; or

         (c) for or by any rent or additional rent which Tenant might have paid
for more than the current month to any prior landlord (including Landlord); or

         (d) by any amendment or modification of the Lease made without Lender's
consent which would either reduce the rent payment under the Lease, reduce the
term of the Lease or impose financial obligations on Landlord not currently
existing under the Lease; or

         (e) for any security deposit, rental deposit or similar deposit given
by Tenant to a prior landlord (including landlord) unless such deposit is
actually paid over to Lender or such purchaser by the prior landlord; or

         (f) for any portion of the Tenant Allowance ( as such term is defined
in the Lease) previously disbursed to Landlord by Lender pursuant to the
Construction Loan Agreement executed by and between Landlord and Lender; or

         (g) for the construction of any improvements required of Landlord under
the Lease in the event Lender or such purchaser acquires title to the Mortgaged
Premises prior to full completion and acceptance by Tenant of 


                                       52

<PAGE>   55

improvements required under the Lease, provided, however, such lack of liability
on the part of the Lender or such purchaser pursuant to this subparagraph shall
not affect Tenant's rights described in the Lease in the event of such failure
to complete such improvements as long as Tenant has provided all applicable
notices and cure periods as required under the Lease and this Agreement, and if
Lender or such purchaser elects not to complete or perform such construction
after acquiring title to the Mortgaged Premises, and Tenant has complied with
the notice and cure periods provided for in the Lease as contemplated above,
Tenant shall have the right at any time thereafter but prior to the date Lender
or such purchaser recommences such construction and pursues same with all due
diligence, to terminate this Lease by written notice of termination to Lender or
such purchaser; or

         (h) for the payment of any leasing commissions or other expenses for
which any prior landlord (including Landlord) incurred the obligations to pay;
or

         (i) by any provision of the Lease restricting use of other properties
owned by Lender, as landlord; or

         (j) by any notice given by Tenant to a prior landlord (including
Landlord) unless a copy thereof was also then given to Lender.

The person or entity to whom Tenant attorns shall be liable to Tenant under the
Lease only for matters arising during such person's or entity's period of
ownership, and such liability shall terminate upon the transfer by such person
or entity of its interest in the Lease and Mortgaged Premises.

         5. No Abridgment. Nothing herein contained is intended, nor shall it be
construed, to abridge or adversely affect any right or remedy of Landlord under
the Lease in the event of any default by Tenant (beyond and period given Tenant
to cure such default) in the payment of rent or additional rent or in the
performance of any of the other terms, covenants or conditions of the Lease on
Tenant's part to be performed.

         6. Notices of Default to Lender. Tenant agrees to give Lender a copy of
any default notice sent by Tenant to Landlord under the Lease.

         7. Representations by Tenant. Tenant represents and warrants to Lender
that Tenant has validly executed the Lease; the Lease is valid, bringing and
enforceable and is in full force and effect in accordance with its terms; the
Lease has not been amended except as stated herein; no rent under the Lease has
been paid more than thirty (30) days in advance of its due date; there are no
defaults existing under the Lease; and Tenant, as of this date, has no charge,
lien, counterclaim or claim of offset under the Lease, or otherwise, against the
rents or other charges due or to become due under the Lease.

         8. Rent Payment. If Lender shall become the owner of the Mortgaged
Premises or the Mortgaged Premises shall be sold by reason of non-judicial or
judicial foreclosure or other proceedings brought to enforce the Security
Instrument or the Mortgaged Premises shall be conveyed by deed in lieu of
foreclosure, Tenant agrees to pay all rents directly to Lender or other
purchaser of the Mortgaged Premises, as the case may be, in accordance with the
Lease immediately upon notice of Lender or such purchaser, as the case may be,
succeeding to Landlord's interest under the Lease. Tenant further agrees to pay
all rents directly to Lender immediately upon that Lender is exercising its
rights to such rents under the Security Instrument or any other loan documents
(including but not limited to any Assignment of Leases and Rents) following a
default by Landlord of other applicable party. Tenant shall be under no
obligation to ascertain whether a default by Landlord has occurred under the
Security Instrument or any other loan documents. Landlord waives any right,
claim or demand it may now or hereafter have against Tenant by reason of such
direct payment to Lender and agrees that such direct payment to Lender shall
discharge all obligations of Tenant to make such payment to Landlord.

         9. Notice of Security Instrument. To the extent that the Lease shall
entitle Tenant to notice of any deed of trust or security agreement, this
Agreement shall constitute such notice to the Tenant with respect to the
Security 

                                       53



<PAGE>   56

Instrument and to any and all other deeds of trust and security agreements which
may hereafter be subject to the terms of this Agreement.

         10. Landlord Defaults. Tenant agrees with Lender that effective as the
date of this Agreement: (i) Tenant shall not take any steps to terminate the
Lease for any default by Landlord or any succeeding owner of the Mortgaged
Premises until after giving Lender written notice of such default by Landlord or
any succeeding owner of the Mortgaged Premises until after giving Lender written
notice of such default, stating the nature of the default and giving Lender
thirty (30) days from receipt of such notice to effect cure of the same, or if
cure cannot be effected within said thirty (30) days due to the nature of the
default, Lender shall have a reasonable time to cure provided that it commences
cure within said thirty (30) day period of time and diligently carries such cure
to completion; and (ii) notice to Landlord shall not constitute notice to
Lender.

         11. Liability of Lender. If Lender shall become the owner of the
Mortgaged Premises or the Mortgaged Premises shall be sold by reason of
foreclosure or other proceedings brought to enforce the Security Instrument or
the Mortgaged Premises shall be conveyed by deed in lieu of foreclosure, Tenant
agrees that, notwithstanding anything to the contrary contained in the Lease,
after such foreclosure, Lender shall have no personal liability to Tenant under
the Lease and Tenant shall look solely to the estate and property of Landlord in
the Mortgaged Premises, to the net proceeds of sale thereof or the rentals
received therefrom, for the satisfaction of Tenant's remedies for the collection
of a judgment or other judicial process requiring the payment of money by the
Landlord in the event of any default or breach by Landlord with respect to any
of the terms, covenants, and conditions of the Lease to be observed or performed
by Landlord and any other obligation of Landlord created by or under this Lease,
and no other property or assets of Landlord or of its partners, officers,
beneficiaries, co-tenants, shareholders, or principals (as the case may be)
shall be subject to levy, execution or other enforcement procedures for the
satisfaction of Tenant's remedies. The term "Landlord" as used herein shall be
limited to mean and include only the owner or owners at the time in question of
Landlord's interest in the Lease, which term shall include Lender in the event
Lender acquires title to the mortgaged Premises. Further, in the event of any
transfer by the Landlord of Landlord's interest in this Lease, Landlord (and in
the case of any subsequent transfers or conveyances, the then assignor),
including each of its partners, officers, beneficiaries, co-tenants,
shareholders or principals ( as the case may be) shall be automatically freed
and released, from and after the date of such transfer or conveyance, of all
liability for the performance of any covenants and agreements which accrue
subsequent to the date of such transfer of Landlord's interest.

         12. Notice. Any notice or communication required or permitted hereunder
shall be given in writing, sent by (a) personal delivery, or (b) expedited
delivery service with proof of delivery, or (c) United States mail, postage
prepaid, registered or certified mail, or (d) telegram, addressed as follows:

         To Lender:                       ______________________________________
                                          ______________________________________
                                          ______________________________________
                                          Attention:  __________________________


         To Tenant:                       ______________________________________
                                          ______________________________________
                                          ______________________________________
                                          ______________________________________

or to such other address or to the attention of such other person as hereafter
shall be designated in writing by the applicable party sent in accordance
herewith. Any such notice or communication shall be deemed to have been given
and received either at the time of personal delivery or, in the case of delivery
service or mail, as of the date of the first 

                                       54



<PAGE>   57

attempted delivery at the address and in the manner provided herein, or in the
case of telegram, upon receipt.

         13. No Amendment Assignment or Subletting of Lease. Lender and Tenant
agree that Tenant's interest in and obligations under the Lease shall not be
altered or modified without the prior written consent of Lender. Lender and
Tenant also agree that Tenant shall neither assign the Lease or allow it to be
assigned in any manner nor sublet the Demised Premises or any part thereof
without the prior written consent of Lender in any situation where Landlord's
consent to any such action required under the Lease (provided such consent by
Lender shall be subject to the same time frame and substantive standard of
review as is applicable to Landlord under the terms of the Lease).

         14. No Termination of Lease. Tenant agrees that during the term of this
Agreement, Tenant will not enter into consensual termination of the Lease with
Landlord without prior written consent of Lender.

         15. Modification. This Agreement may not be modified orally or in any
manner other than by an Agreement in writing signed by the parties hereto or
their respective successors in interest.

         16. Successors of Lender . The term "Lender" as used throughout this
Agreement includes any successor of assign of Lender and any holder (s) of any
interest in the indebtedness secured by the Security Instrument.

         17. Successors and Assigns. This Agreement shall inure to the benefit
of and be binding upon parties hereto, their successors and assigns, and any
purchasers at foreclosure of the Mortgaged Premises, and their respective
successors and assigns.

         18. Paragraph Headings. The paragraph headings contained in this
Agreement are for convenience only and shall in no way enlarge or limit the
scope or meaning of the various and several paragraphs hereof.

         19. Gender and Number. Within this Agreement, words of any gender shall
be held and construed to include any other gender, and words in the singular
number shall be held and construed to include the plural and words in the plural
number shall be held and construed to include the singular, unless the context
otherwise requires.

         20. Applicable Law. This Agreement and the rights and duties of the
parties hereunder shall be governed by all purposes by the law of the state
where the Mortgaged Premises is located and the law of the United States
applicable to transactions within such state.


                                       55
<PAGE>   58




         IN WITNESS WHEREOF, the parties hereto have hereunto caused this
Agreement to be duly executed as of the day and year first above written


                                 ----------------------------------------------,
                                  a _______________________


                                 By: _________________________________
                                 Name:________________________________
                                 Title:_______________________________
                                                                       LENDER


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


                                 By: _________________________________
                                 Name:________________________________
                                 Title:_______________________________
                                                                       TENANT

                                 FCP-DULLES BUSINESS PARK I, L.C., a Virginia 
                                 limited liability company

                                 By: CRIMSON PARTNERS, L.C., a Virginia limited
                                     liability company


                                 By:                                      (SEAL)
                                    ---------------------------------------
                                 Name:  R. Kevin Dougherty
                                 Title: Managing Member
                                 Date: _________________________________________

                                                                        LANDLORD

                              CONSENT OF GUARANTOR




         ___________________________________________________________ as the
Guarantor of Tenant's obligations under the Lease, joins in the execution hereof
to evidence its consent to the provisions above its agreement that, so long as
Tenant shall be required to attorn to Lender or any other party pursuant to the
provisions above, the Guaranty of the Lease shall survive and continue in favor
of the party to whom Tenant must attorn.






                              --------------------------------------------------
                                                  GUARANTOR

                                       56
<PAGE>   59

                                   EXHIBIT F

                               GUARANTY AGREEMENT

         THIS GUARANTY AGREEMENT ("Guaranty") is given as of the 8th day of May,
1998, by NATIONAL INSURANCE GROUP, a California corporation having an address at
395 Oyster Point, Suite 500, South San Francisco, CA 94080 ("Guarantor"), for
the benefit of FCP-DULLES BUSINESS PARK I, L.C., a Virginia limited liability
company ("Landlord") having an address at c/o Crimson Partners, L.C., 455 Spring
Park Place, Suite 100, Herndon, Virginia 22070, Attn: R. Kevin Dougherty, with
respect to certain obligations of PINNACLE REAL ESTATE TAX SERVICES, INC., a
Delaware corporation ("Tenant").

                                    RECITALS

         Pursuant to that certain Deed of Lease dated as of May 8, 1998, by and
between Landlord and Tenant (the "Lease", such term to include all extensions,
renewals, amendments and modifications thereof and substitutions therefor),
Tenant has leased from Landlord certain premises consisting of approximately
33,322 square feet of space located in the Wright I Building, Dulles Business
Park, Suite 200, 14026 Thunderbolt Place, Chantilly, Virginia 22021 (the "Leased
Premises"). Landlord is willing to enter into the Lease only if Guarantor gives
the Guaranty provided in this Guaranty Agreement. Guarantor is willing to enter
into this Guaranty Agreement so as to induce Landlord to enter into the Lease.

         NOW, THEREFORE, in consideration of these premises and other good and
valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, the Guarantor, intending to be legally bound hereby, gives the
following Guaranty and indemnification to and for the benefit of Landlord.

                  Section 1. Guaranty. Except as, and solely to the extent,
limited by Section 32, below, the Guarantor guaranties the timely, complete,
continuous, and strict performance and observance by the Tenant of any and all
of the terms, covenants, agreements, and conditions contained in the Lease, both
monetary and non-monetary, and any existing or future documents, instruments,
agreements, and writings of every kind, nature, type, and variety which
evidence, reflect, embody, or secure the Lease, and all amendments,
modifications, and restatements thereof. The Guarantor hereby holds harmless and
indemnifies Landlord from and against any and all costs, claims, loss and
expenses, including attorneys' fees, incurred by Landlord as a result of a
failure by the Tenant or the Guarantor to satisfy the obligations imposed by the
Lease and/or this Guaranty. As used in this Guaranty, the term "Obligations"
shall refer to all obligations which the Guarantor has undertaken and assumed
pursuant to this Guaranty, both as described in this Section and in other
Sections of this Guaranty.

                  Section 2. Nature Of Guaranty. This Guaranty: (a) is (i)
irrevocable, and (ii) one of payment and not just collection; and (b) makes the
Guarantor a surety to Landlord with respect to the Obligations.

                  Section 3. Representations And Warranties Of Guarantor. The
Guarantor represents and warrants to Landlord that: (a) Guarantor is a validly
constituted corporation, created and existing under the laws of the State of
California, and has duly filed of public record all necessary certificates,
filings and consents to service of process required under all applicable laws;
(b) Guarantor has the full power to own its properties, to conduct its affairs,
to incur the Obligations and to enter into this Guaranty; (c) the execution and
delivery by the Guarantor of this Guaranty is in full accord with all of the
applicable provisions and requisites of the Guarantor's certificate of
incorporation and bylaws, and no consent of any party is necessary as a
prerequisite to the execution of this Guaranty Agreement by, and the enforcement
of this Guaranty Agreement against, Guarantor; and (d) the entering into and
performance of its obligations hereunder by Guarantor, including the
Obligations, is not in contravention with and will not constitute a default
under any agreement, indenture, credit agreement or other instrument to which
Guarantor is a party or to which it or its property is or may be bound.


                                       57

<PAGE>   60

                  Section 4. Landlord Need Not Pursue Other Rights. Landlord
shall be under no obligation to pursue Landlord's rights under the Lease against
the Tenant before pursuing Landlord's rights against the Guarantor. Specifically
(but not by way of limitation), Guarantor waives the benefits of the provisions
of Sections 49-25 and 49-26 of the Code of Virginia.

                  Section 5. Certain Rights Of Landlord. The Guarantor hereby
assents to any and all terms and agreements between Landlord and the Tenant as
contained in the Lease, and all amendments and modifications thereof, whether
presently existing or hereafter made and whether oral or in writing. Landlord
may, without compromising, impairing, diminishing, or in any way releasing the
Guarantor from the Obligations and, without notifying or obtaining the prior
approval of the Guarantor, at any time or from time to time: (a) waive or excuse
a default by the Tenant, or delay in the exercise by Landlord of any or all of
Landlord's rights or remedies under the Lease with respect to such default or
defaults; (b) grant extensions of time for payment or performance by the Tenant;
(c) release, substitute, exchange, surrender, or add collateral of the Tenant or
waive, release, or subordinate, in whole or in part, any lien or security
interest held by Landlord on any real or personal property securing payment or
performance, in whole or in part, of the obligations of the Tenant to Landlord;
and (d) modify, change, renew, extend, or amend in any respect, the Lease, or
any document, instrument, or writing embodying or reflecting the same.

                  Section 6. Waivers By Guarantor. Except as provided in this
Section 6, below, Guarantor waives: (a) any and all notices whatsoever with
respect to this Guaranty or with respect to any of the obligations of the Tenant
to Landlord, including, but not limited to, notice of (i) Landlord's acceptance
hereof or Landlord's intention to act, or Landlord's action, in reliance hereon,
(ii) the present existence or future incurring of any of the obligations of the
Tenant to Landlord or any terms or amounts thereof or any change therein, (iii)
any default by the Tenant or any surety, pledgor, grantor of security, or any
person who has guarantied or secured in whole or in part the obligations of the
Tenant to Landlord, and (iv) the obtaining or release of any guaranty or surety
agreement, pledge, assignment, or other security for any of the obligations of
the Tenant to Landlord; (b) presentment and demand for payment of any sum due
from the Tenant and protest of nonpayment; and (c) demand for performance by the
Tenant. The foregoing notwithstanding, Guarantor does not waive its right to
receive notice of Tenant's default as and to the extent required pursuant to
Section 22.1 of the Lease.

                  Section 7. Subrogation Rights. Landlord shall have no duty or
obligation to Guarantor under the Lease or otherwise to take any action (or not
to fail to take any action) in order to preserve any right of subrogation
Guarantor might otherwise have against Tenant under applicable law by virtue of
Guarantor's performance of Tenant's Lease obligations under this Guaranty.

                  Section 8. Unenforceability Of Obligations Of Tenant. This
Guaranty shall be valid, binding, and enforceable even if the obligations of the
Tenant to Landlord which are guarantied hereby are now or hereafter become
invalid or unenforceable for any reason, including by adjudication under the
United States Bankruptcy Code.

                  Section 9. No Conditions Precedent. This Guaranty shall be
effective and enforceable immediately upon its execution. The Guarantor
acknowledges that no unsatisfied conditions precedent to the effectiveness and
enforceability of this Guaranty exist as of the date of its execution and that
the effectiveness and enforceability of this Guaranty is not in any way
conditioned or contingent upon any event, occurrence, or happening, or upon any
condition existing or coming into existence either before or after the execution
of this Guaranty.

                  Section 10. No Duty To Disclose. Landlord shall have no
present or future duty or obligation to discover or to disclose to the Guarantor
information, financial or otherwise, concerning the Tenant, any other guarantor,
or any collateral securing either the obligations of the Tenant to Landlord or
of any other person who may have guarantied in whole or in part the obligations
of the Tenant to Landlord. The Guarantor waives any right to claim or assert any
such duty or obligation on the part of Landlord.

                  Section 11. Existing Or Future Guaranties. The execution of
this Guaranty Agreement shall not 

                                       58

<PAGE>   61

discharge, terminate or in any way impair or adversely affect the validity or
enforceability of any other guaranty given by the Guarantor to Landlord, even if
such other guaranty pertains to the obligations of the Guarantor with respect to
the Lease. Nor shall the execution of any future guaranty by the Guarantor in
favor of Landlord or any of its members individually discharge, terminate, or in
any way impair or adversely affect the validity or enforceability of this
Guaranty. All guaranties given by the Guarantor to Landlord shall be cumulative
and shall remain in full force and effect until discharged and terminated in
accordance with their provisions, upon satisfaction of all the guarantied
obligations.

                  Section 12. Cumulative Liability. The liability of the
Guarantor under this Guaranty shall be cumulative to, and not in lieu of, the
Guarantor's liability under any other document or instrument by and between
Guarantor and Landlord or any of its members individually.

                  Section 13. Obligations Are Unconditional. The Obligations are
the absolute and unconditional duty and obligation of the Guarantor, and shall
be independent of any defense or any rights of setoff, recoupment or
counterclaim which the Guarantor might otherwise have against Landlord, and the
Guarantor shall pay and perform these Obligations free of any deductions and
without abatement, diminution or setoff; provided, however that notwithstanding
anything to the contrary herein contained, the Guarantor's obligation hereunder
in respect of the Lease shall not be greater than those of the Tenant, plus the
cost of Landlord's enforcement hereunder. Until such time as the Obligations
have been fully paid and performed, the Guarantor: (a) shall not suspend or
discontinue any payments provided for herein; (b) shall perform and observe all
of the covenants and agreements contained in this Guaranty; and (c) shall not
terminate or attempt to terminate this Guaranty for any reason. No delay by
Landlord in making demand on the Guarantor for satisfaction of the Obligations
shall prejudice or in any way impair Landlord's ability to enforce this
Guaranty.

                  Section 14. Expenses Of Collection And Attorneys' Fees. Should
this Guaranty be referred to an attorney for collection, the Guarantor shall pay
all of the holder's reasonable costs, fees and expenses resulting from such
referral, including reasonable attorneys' fees, which the holder may incur, even
though judgment has not been confessed or suit has not been filed. Guarantor's
liability under this Section 14 be in addition to, and shall apply without
regard to, any limitation on the Guarantor's liability set forth in Section 32,
below,

                  Section 15. Enforcement During Bankruptcy. Enforcement of this
Guaranty shall not be stayed or in any way delayed as a result of the filing of
a petition under the United States Bankruptcy Code, as amended, by or against
the Tenant.

                  Section 16. Remedies Cumulative. All of Landlord's rights and
remedies shall be cumulative and any failure of Landlord to exercise any right
hereunder shall not be construed as a waiver of the right to exercise the same
or any other right at any time, and from time to time, thereafter.

                  Section 17. Discharge Of Guaranty. This Guaranty shall not be
discharged and the Guarantor shall not be released from liability until all
Obligations have been satisfied in full and the satisfaction of such Obligations
is not subject to challenge or contest. If all or any portion of such
Obligations are satisfied and Landlord is required for any reason to pay to any
person the sums used to satisfy such Obligations, such Obligations shall remain
in effect and enforceable to the extent thereof.

                  Section 18. Subordination Of Certain Indebtedness. If the
Guarantor advances any sums to the Tenant or its successors or assigns or if the
Tenant or its successors or assigns shall become indebted to the Guarantor, such
sums and indebtedness shall be subordinate in all respects to the amounts then
or thereafter due and owing to Landlord by the Tenant.

                  Section 19. Renewals, Extensions Etc. This Guaranty shall
apply to all sums now or hereafter owed by the Tenant to Landlord pursuant to
the Lease, and to all extensions, modifications, amendments, renewals,
substitutions, and expansions of the Lease.

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                  Section 20. Choice Of Law. The laws of the Commonwealth of
Virginia (excluding, however, conflict of law principles) shall govern and be
applied to determine all issues relating to this Guaranty and the rights and
obligations of the parties hereto, including the validity, construction,
interpretation, and enforceability of this Guaranty and its various provisions
and the consequences and legal effect of all transactions and events which
resulted in the issuance of this Guaranty or which occurred or were to occur as
a direct or indirect result of this Guaranty having been executed.

                  Section 21. Consent To Jurisdiction; Agreement As To Venue.
The Guarantor irrevocably consents to the non-exclusive jurisdiction of the
courts of the Commonwealth of Virginia and of any division of the United States
District Court for Eastern District of Virginia, if a basis for federal
jurisdiction exists. The Guarantor agrees that venue shall be proper in any
court of the Commonwealth of Virginia selected by Landlord or in the United
States District Court for the Eastern District of Virginia, if a basis for
federal jurisdiction exists.

                  Section 22. Invalidity Of Any Part. If any provision or part
of any provision of this Guaranty shall for any reason be held invalid, illegal,
or unenforceable in any respect, such invalidity, illegality, or
unenforceability shall not affect any other provisions or the remaining part of
any effective provisions of this Guaranty, and this Guaranty shall be construed
as if such invalid, illegal, or unenforceable provision or part thereof had
never been contained herein, but only to the extent of its invalidity,
illegality, or unenforceability.

                  Section 23. Amendment Or Waiver. This Guaranty may be amended
only by a writing duly executed by the Guarantor and Landlord. No waiver by
Landlord of any of the provisions of this Guaranty or any of the rights or
remedies of Landlord with respect hereto shall be considered effective or
enforceable unless in writing.

                  Section 24. Notices. All notices, requests and demands upon
the respective parties hereto shall be given by hand delivery, by recognized
overnight courier, or by United States mail, postage prepaid, certified or
registered mail, return receipt requested, addressed as set forth in the Lease,
or to such other address as either party may furnish in writing to the other for
such purpose. Such notices shall be deemed to have been given or made upon the
earlier to occur of actual receipt or refusal of delivery by the intended
recipient.

                  Section 25. Binding Nature. This Guaranty shall inure to the
benefit of and be enforceable by Landlord and Landlord's successors, assigns and
any other person to whom Landlord may grant an interest in the Obligations,
including any assignee or designee of the landlord's interest under the Lease,
and shall be binding upon and enforceable against the Guarantor and the
Guarantor's successors and assigns.

                  Section 26. Final Agreement. This Guaranty contains the final
and entire agreement between Landlord and the Guarantor with respect to the
Obligations. There are no separate oral or written understandings between
Landlord and the Guarantor with respect thereto.

                  Section 27. Tense, Gender, Defined Terms, Captions. As used
herein, the plural includes the singular, and the singular includes the plural.
The use of any gender applies to any other gender. All captions are for the
purpose of convenience only.

                  Section 28. Seal And Effective Date. This Guaranty is an
instrument executed under seal and is to be considered effective and enforceable
as of the date set forth on the first page hereof, independent of the date of
actual execution.

                  Section 29. Waiver Of Trial By Jury. The Guarantor hereby
agrees that any suit, action, or proceeding, whether claim or counterclaim,
brought or instituted by either party hereto or any successor or assign of any
party on or with respect to this Guaranty or which in any way relates, directly
or indirectly, to this Guaranty or any event, transaction, or occurrence arising
out of or in any way connected with this Guaranty, or the dealings of the
parties with respect thereto, shall be tried only by a court and not by a jury.
Guarantor HEREBY EXPRESSLY 

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WAIVES ANY RIGHT TO A TRIAL BY JURY IN ANY SUCH SUIT, ACTION, OR PROCEEDING. The
Guarantor acknowledges and agrees that this Section is a specific and material
aspect of this Guaranty and that Landlord would not accept this Guaranty if this
waiver of jury trial Section were not a part of this Guaranty.

                  Section 30. Defenses Against Tenant. The Guarantor waives any
right to assert against Landlord any defense (whether legal or equitable),
claim, counterclaim, or right of setoff or recoupment which the Guarantor may
now or hereafter have against the Tenant.

                  Section 31. Continuing Guaranty. This Guaranty is a continuing
Guaranty of all existing and future obligations of the Tenant to Landlord in
connection with the Lease, and may not at any time be terminated by the
Guarantor. This Guaranty may be terminated only in writing by Landlord and upon
such terms and conditions as Landlord may impose. The foregoing provisions of
this Section 31 shall not affect any limitations upon this Guaranty or upon the
obligations of Guarantor which are set forth in Section 32, below. The foregoing
provisions of this Section 31 to the contrary notwithstanding, in the event of
any permitted assignment of the Lease under circumstances where the assignee (or
any entity guarantying the Lease as part of such assignment transaction pursuant
to a Guaranty in favor of Landlord which is substantially identical to this
Guaranty and which is executed and delivered to Landlord as of the effective
date of such permitted assignment) has a tangible net worth as of the effective
date of such permitted assignment which equals or exceeds the greater of (i) the
tangible net worth of Guarantor as of the date of execution of this Guaranty, or
(ii) the tangible net worth of Guarantor as of the effective date of such
permitted assignment, then Guarantor shall be released from its obligations
under this Guaranty to the extent the same have been assumed in writing or by
operation of law by such assignee or new guarantor.

                  Section 32. Limitation of Guarantor's Liability. (a) Subject
(i) to Section 32(b), below, and (ii) any amounts for which Guarantor is liable
under Section 14, above, but notwithstanding any other provision of this
Guaranty to the contrary, Guarantor's monetary liability to Landlord under this
Guaranty shall initially be limited to an amount (the "Limit of Guarantor's
Liability") equal to one hundred percent (100%) of the "Total Lease-Up Cost" (as
such term is hereinafter defined). In addition, provided Tenant has not
committed an "Event of Default" as defined in the Lease which is then continuing
(or any action or omission which, with the giving of notice or the passage of
time, or both, would constitute an Event of Default by Tenant under the Lease),
then as of the first day of each Lease Year, the Limit of Guarantor's Liability
shall equal (and, as applicable, be reduced to) that percentage of the Total
Lease-Up Cost as is set forth in the following schedule:
<TABLE>
<CAPTION>


                                        Percentage of Total Lease-Up Cost
                 Lease Year              as to which Guarantor's Liability 
                                              Hereunder is Limited

<S>                                     <C> 
                     1                                100%
                     2                                 90%
                     3                                 80%
                     4                                 70%
                     5                                 60%
                     6                                 50%
                     7                                 40%
                     8                                 30%
                     9                                 20%
                    10                                 10%
                 Renewal Term                      No Liability
</TABLE>

The "Total Lease-Up Cost" shall mean the sum of (i) the Improvement Allowance
paid by Landlord pursuant to Exhibit B, (ii) any Excess Costs funded by Landlord
pursuant to Exhibit B, and (iii) the total aggregate amount of leasing
commissions paid by Landlord in respect of this Lease to Landlord's Broker and
to Tenant's Broker. By way of hypothetical example, and not of limitation, if
the Total Lease-Up Cost equals One Million Three Hundred 

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Thousand Dollars ($1,300,000), then the Limit of Guarantor's Liability during
the fourth (4th) Lease Year shall be Nine Hundred Ten Thousand Dollars
($910,000).

         (b) Notwithstanding Section 32(a), above, to the contrary, Guarantor
agrees that (i) during the continuation of any failure by Tenant to provide any
of the financial statements described in Section 28.4(b) of the Lease, and/or
(ii) in the event any financial information certified as true and correct by
Guarantor and provided by Tenant to Landlord under Section 28.4(b) of the Lease
is materially inaccurate or incomplete, the Limitation of Guarantor's Liability
shall cease to be applicable, and Guarantor's liability to Landlord pursuant to
this Guaranty shall not be limited, as if Section 32(a) were no longer a part of
this Guaranty.

         IN WITNESS WHEREOF, the Guarantor has duly executed this Guaranty under
seal as of the date first above written (notwithstanding the actual date of
execution and delivery hereof).


ATTEST/WITNESS:               GUARANTOR:

                              NATIONAL INSURANCE GROUP, a California corporation


____________________          By: _______________________________(SEAL)
(Corporate Seal)                  Greg Saunders, Chief Financial Officer




                                 ACKNOWLEDGMENT

STATE OF ___________________________________:
                                            : TO WIT:
CITY/COUNTY OF _________________:

         I HEREBY CERTIFY that on this _____ day of May, 1998 before me, the
undersigned Notary Public of the aforesaid jurisdiction, personally appeared
Greg Saunders, who acknowledged himself to be the Chief Financial Officer of
National Insurance Group, a California corporation, who, being authorized so to
do, executed the foregoing Guaranty for the purposes therein contained by
signing the name of said corporation, by himself, as such Chief Financial
Officer.

         WITNESS MY Hand and Notarial Seal.


                                      ____________________________________(SEAL)
                                      NOTARY PUBLIC
My Commission expires:
[Seal]




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