<PAGE>   1
                                                                    EXHIBIT 10.2

                 * * * * * * * * * * * * * * * * * * * * * * * *
                                 LEASE AGREEMENT

                                     BETWEEN

                            Park West E-3 Associates,
                              a Texas joint venture

                                   (Landlord)

                                       AND

                  NETCOM On-Line Communications Services, Inc.,

                             a Delaware corporation

                                    (Tenant)

                                  Park West E-3
                                1607 LBJ Freeway
                                  Dallas, Texas

                            Dated: February ___,1996

                 * * * * * * * * * * * * * * * * * * * * * * * *



<PAGE>   2


                      TABLE OF CONTENTS - LEASE AGREEMENT

<TABLE>
<CAPTION>
                                                                                                      Page
                                                                                                      ----

<S>                                                                                           <C>
ARTICLE 1 BASIC LEASE INFORMATION AND CERTAIN DEFINITIONS............................................1

ARTICLE 2 PREMISES AND QUIET ENJOYMENT...............................................................4

ARTICLE 3 TERM; COMMENCEMENT DATE DELIVERY AND ACCEPTANCE OF PREMISES................................6

ARTICLE 4 RENT.......................................................................................9

ARTICLE 5 OPERATING COSTS............................................................................10

ARTICLE 6 PARKING....................................................................................18

ARTICLE 7 SERVICES OF LANDLORD.......................................................................19

ARTICLE 8 ASSIGNMENT AND SUBLETTING..................................................................23

ARTICLE 9 REPAIRS....................................................................................26

ARTICLE 10 ALTERATIONS...............................................................................30

ARTICLE 11 LIENS.....................................................................................32

ARTICLE 12 USE AND COMPLIANCE WITH LAWS..............................................................33

ARTICLE 13 DEFAULT AND REMEDIES......................................................................34

ARTICLE 14 INSURANCE.................................................................................36

ARTICLE 15 DAMAGE BY FIRE OR OTHER CAUSE.............................................................39

ARTICLE 16 CONDEMNATION..............................................................................40

ARTICLE 17 INDEMNIFICATION...........................................................................42

ARTICLE 18 SUBORDINATION AND ESTOPPEL CERTIFICATES...................................................44

ARTICLE 19 SURRENDER OF THE PREMISES.................................................................47

ARTICLE 20 LANDLORD'S RIGHT TO INSPECT...............................................................48

ARTICLE 21 SECURITY DEPOSIT [INTENTIONALLY DELETED]..................................................49
</TABLE>


                                     - i -
<PAGE>   3
<TABLE>
<S>                                                                                           <C>
ARTICLE 22 BROKERAGE.................................................................................49

ARTICLE 23 OBSERVANCE OF RULES AND REGULATIONS.......................................................50

ARTICLE 24 NOTICES...................................................................................50

ARTICLE 25 MISCELLANEOUS.............................................................................51

ARTICLE 26 SUBSTITUTION SPACE [ARTICLE 26 INTENTIONALLY DELETED].....................................55

ARTICLE 26 INTENTIONALLY DELETED.....................................................................55

ARTICLE 27 OTHER DEFINITIONS.........................................................................55

ARTICLE 28 BUILDING NAME AND TENANT SIGNAGE..........................................................57

ARTICLE 29 NON-COMPETITION...........................................................................58

ARTICLE 30 ANTENNA AND HVAC SYSTEMS..................................................................59

ARTICLE 31 RIGHT TO TERMINATE FOR FAILURE TO PROVIDE SERVICES OR DUE TO HAZARDOUS SUBSTANCES.........60
</TABLE>

                                     - ii -
<PAGE>   4


                               EXHIBITS AND RIDERS

              The following Exhibits and Riders are attached hereto and by this
reference made a part of this Lease:


EXHIBIT A                  -        FLOOR PLAN OF THE PREMISES

EXHIBIT B                  -        THE LAND

EXHIBIT C                  -        LEASEHOLD IMPROVEMENTS

EXHIBIT D                  -        FORM OF COMMENCEMENT NOTICE

RIDER NO. 1                -        RULES AND REGULATIONS

RIDER NO. 2                -        EXTENSION OPINION

RIDER NO. 3                -        MUST TAKE EXPANSION

RIDER NO. 4                -        RIGHT TO TERMINATE LEASE

RIDER NO. 5                -        GENERAL ARBITRATION


                                     - iii -
<PAGE>   5


                             INDEX OF DEFINED TERMS

                  Definitions of certain terms used in this Lease are found in
the following sections:

<TABLE>
<CAPTION>
         TERM                                                                               LOCATION OF DEFINITION
<S>                                                                                            <C>
         Additional Rent                                                                            Section 1.01 N
         Bankruptcy Code                                                                              Section 8.06
         Base Building Condition                                                                         Exhibit C
         Base Rent                                                                                   Section 1.02M
         Basic Lease Information and Certain Definitions                                                 Article 1
         Branch                                                                                          Exhibit C
         Broker                                                                                      Section 1.01W
         Building                                                                                    Section 1 01B
         Building Standard                                                                               Exhibit C
         Business Days                                                                                  Article 27
         Central                                                                                         Exhibit C
         Commencement Date                                                                           Section 1.01F
         Common Areas                                                                                   Article 27
         days                                                                                           Article 27
         Events of Default                                                                           Section 13.01
         Expiration Date                                                                             Section 1.01G
         herein, hereof, hereby, hereunder and words
              of similar import                                                                         Article 27
         include and including                                                                          Article 27
         Interest Rate                                                                                Section 4.02
         Land                                                                                        Section 1.01C
         Landlord                                                                                         Preamble
         Landlord's Address for Notice                                                               Section I 01T
         Landlord's Address for Payment                                                             Section 1 01 U
         Landlord's Operating Costs Estimate                                                          Section 5011
         Landlord's Work                                                                                 Exhibit C
         Leasehold Improvements                                                                          Exhibit C
         Net Rentable Area                                                                              Article 27
         Net Rentable Area of the Building                                                           Section 1.011
         Net Rentable Area of the Premises                                                           Section 1.011
         Non-Building Standard                                                                           Exhibit C
         Parking Facility                                                                           Section 1.01 D
         Parking Permits                                                                             Section 1.01P
         Permit Fees                                                                                Section 1.01 P
         Project                                                                                     Section l.01E
         Premises                                                                                    Section 1.01A
         Reference to Landlord as having "no liability
</TABLE>

                                     - iv -
<PAGE>   6

<TABLE>
<S>                                                                                     <C>
         to Tenant or being" without liability to
         Tenant" or words of like import                                                                Article 27
         Rent                                                                                        Section 1.01L
         repair                                                                                         Article 27
         Security Deposit                                                                           Section 1.01 R
         Successor Landlord                                                                          Section 18.02
         Taxes                                                                                        Section 5.02
         Tenant                                                                              Preamble & Article 27
         Tenant Delay                                                                                    Exhibit C
         Tenant's Address for Notice                                                                Section 1 01 V
         Tenant's Allowance                                                                              Exhibit C
         Tenant's Permitted Uses                                                                     Section 1.01Q
         Tenant's Property                                                                       Section 14.01A(a)
         Tenant's Share                                                                              Section 1.01K
         Tenant's Work                                                                                   Exhibit C
         Term
         termination of this Lease and words of like import                                             Article 27
         terms of this Lease                                                                            Article 27
         this Lease                                                                                       Preamble
         Usable Area of Premises                                                                         Exhibit C
         year
</TABLE>



                                     - v -
<PAGE>   7

                                 LEASE AGREEMENT

                  THIS LEASE AGREEMENT ("this Lease") is made and entered into
by and between Park West E-3 Associates, a Texas joint venture ("Landlord") and
NETCOM On-Line Communications Services, Inc., a Delaware corporation ("Tenant"),
upon all the terms set forth in this Lease and in all Exhibits and Riders
hereto, to each and all of which terms Landlord and Tenant hereby mutually
agree, and in consideration of One Dollar ($1.00) and other valuable
consideration, the receipt and sufficiency of which are hereby acknowledged, and
of the rents, agreements and benefits flowing between the parties hereto, as
follows:

                                    ARTICLE 1

                 BASIC LEASE INFORMATION AND CERTAIN DEFINITIONS

                  Section 1.01. Each reference in this Lease to information and
definitions contained in the Basic Lease Information and Certain Definitions and
each use of the terms capitalized and defined in this Section 1.01 shall be
deemed to refer to, and shall have the respective meaning set forth in, this
Section 1.01.

A.       Premises:                     The entire first floor of the Building,
                                       presently known as Suite No. 100, as said
                                       space is identified by diagonal lines or
                                       shaded area on the floor plans attached
                                       hereto as Exhibit A and made a part
                                       hereof.

B.       Building:                     The building constructed by Landlord on
                                       that opinion of the Land generally
                                       located at 1607 LBJ Freeway, Dallas,
                                       Texas and being known as Building 11,
                                       Phase 1, Park West Office Community.

C.       Land:                         Those certain parcels of land described
                                       under the caption "Land" in Exhibit B
                                       hereof.

D.       Parking Facility:             The multi-level parking garage which is
                                       adjacent to the Building, including the
                                       parking area adjacent to the Building.

E.       Project:                      The Land and all improvements thereon,
                                       including the Building, the Parking
                                       Facility, and all Common Areas,
                                       excluding, therefrom the buildings
                                       located at 1601, 1603 and 1605 LBJ
                                       Freeway, Dallas, Texas.

F.       Commencement Date:            That certain date on which the Term shall
                                       commence. As determined pursuant to the
                                       provisions of Article 3 hereof.

G.       Expiration Date:              April 30, 2003.



                                     - 1 -
<PAGE>   8

H.       Term:                         Approximately seven (7) years, beginning
                                       on the Commencement Date and ending at
                                       11:59 p.m. on the Expiration Date, unless
                                       this Lease is sooner terminated as
                                       provided herein.

I.       Net Rentable Area of the      50,771 square feet, it being agreed and
         Premises ("NRSF"):            understood that Tenant will pay Base Rent
                                       based on 50.771 NRSF until the Must Take
                                       Date Expansion Space Commencement Date
                                       and thereafter on the basis of 60,827
                                       NRSF.


J        Net Rentable Area of the      60.827 square feet, subject to the
         Building:                     provisions of Section 3.03 hereof.


K.       Tenant's Share:               83.47%, representing a fraction, the
                                       numerator of which is the Net Rentable
                                       Area of the Premises and the denominator
                                       and which is the Net Rentable Area of the
                                       Building (subject to the provisions of
                                       Section 3.03 hereof), subject to future
                                       adjustment.

L.       Rent:                         The Base Rent and the Additional Rent.

M.       Base Rent:                    The Base Rent, which includes Base Year
                                       Operating Costs, shall be $292,655.00 per
                                       annum (approximately 55.764 per annum per
                                       NRSF), for the period beginning thirty
                                       (30) days after the Commencement Date
                                       through the date prior to the first
                                       anniversary of the Commencement Date
                                       based upon 50,771 NRSF: $505,103.00 per
                                       annum (approximately $8.304 per annum per
                                       NRSF), from the first anniversary of the
                                       Commencement Date through the day prior
                                       to the third anniversary of the
                                       Commencement Date based upon 60,827 NRSF:
                                       $677.327.00 per annum (approximately
                                       $11.135 per annum per NRSF of the
                                       Premises), from the third anniversary of
                                       the Commencement Date through the day
                                       prior to the fifth anniversary of the
                                       Commencement Date based upon 60.827 NRSF:
                                       and $812,467.00 per annum ($13.357 per
                                       annum per NRSF of the Premises), from the
                                       fifth anniversary of the Commencement
                                       Date through April 30, 2003 based upon
                                       60.827 NRSF.

N.       Additional Rent:              The Additional Rent shall be all other
                                       sums due and payable by Tenant under the
                                       Lease.


                                     - 2 -
<PAGE>   9


O.       Base Year Operating Costs:    The actual grossed up Operating Costs for
                                       calendar year 1996 for the Project, as
                                       determined on a per NRSF basis.

P.       Parking Permits and           Tenant shall be entitled to two hundred
         Permit Fee:                   twenty (220) Parking Permits for two
                                       hundred twenty (220) unassigned parking
                                       spaces (calculated at the rate of 5
                                       parking spaces per 1,000 NRSF of the
                                       initial Premises), with six (6) parking
                                       permits to be for assigned visitor
                                       parking spaces in the part of the Parking
                                       Facility immediately outside of the
                                       Premises. All parking permits shall be
                                       taken at no charge during the Initial
                                       Term, and shall be used in common with
                                       other persons in the Parking Facility,
                                       with the Parking Permits to increase by
                                       thirty-two (32) Parking Permits upon
                                       Tenant's occupancy of the Must Take
                                       Expansion Space (as defined in Rider No.
                                       3 hereon).

Q.       Tenant's Permitted Uses:      Tenant may use the Premises for executive
                                       and administrative offices for the
                                       conduct of Tenant's business, research
                                       and development, data room, computer and
                                       telecommunications facilities, sales and
                                       marketing, customer service and for any
                                       other lawful purpose incidental thereto,
                                       and for no other use or purpose.

R.       Security Deposit:             None.

S.       Broker:                       CB Commercial Real Estate Group, Inc.,
                                       who shall be paid by Tenant in accordance
                                       with Article 22 hereof.

T.       Landlord's Address            Park West E-3 Associates
         for Notice:                   c/o Prentiss Properties Limited, Inc.
                                       1717 Main Street,
                                       Suite 5000
                                       Dallas, Texas 75201
                                       Attention: Michael V. Prentiss

                                       With a copy to:

                                       Prentiss Properties Limited, Inc.
                                       1509 LBJ Freeway
                                       Dallas, Texas 75234
                                       Attention: Property Management


                                     - 3 -
<PAGE>   10

U.       Landlord's Address            Park West E-3 Associates
         for Payment.                  c/o Prentiss Properties Limited, Inc.
                                       1717 Main Street, Suite 5000
                                       Dallas, Texas 75201

V.       Tenant's Address for Notice:  NETCOM On-Line Communications
                                       Services, Inc.
                                       1607 LBJ Freeway, Suite 100
                                       Dallas, Texas 75234

                                       with a copy to:

                                       NETCOM On-Line Communications
                                       Services, Inc.
                                       3031 Tisch Way, 2nd Floor
                                       San Jose, CA 95134
                                       Attention: Anita Alston,
                                       Director of Corporate Real Estate

                                       and

                                       Pillsbury Madison & Sutro
                                       2700 Sand Hill Road
                                       Menlo Park, CA 94025
                                       Attention: Michael Sullivan, Esq.


                                    ARTICLE 2

                          PREMISES AND QUIET ENJOYMENT

                  Section 2.01. Landlord hereby leases the Premises to Tenant,
and Tenant hereby rents and hires the Premises from Landlord, for the Term.
During the Term, Tenant shall have the right to use, in common with others and
in accordance with the Rules and Regulations, the Common Areas. Landlord and
Tenant each acknowledge that the Building is being developed by Landlord as a
part of a larger complex of office buildings known as the Park West Office
Community (the "Office Park"). Tenant shall have the right to use the common
areas of the Office Park as more particularly set forth in and subject to the
terms and conditions of the Declaration of Covenants, Conditions and
Restrictions (the "Declaration") filed of record in the Deed Records of Dallas,
County, Texas and the Articles of Incorporation and Bylaws of Park West One
Association, Inc., including any existing amendments to any of the foregoing
documents. Landlord hereby acknowledges that nothing contained in the
Declaration shall be contrary to the terms and conditions contained in the
Lease.

                  Section 2.02. Provided that Tenant fully and timely performs
all the terms of this Lease on Tenant's part to be performed, including payment
by



                                     - 4 -
<PAGE>   11

Tenant of all Rent, Tenant shall have, hold and enjoy the Premises during the
Term without hindrance or disturbance from or by Landlord: subject however, to
all of the terms, conditions and provisions of any and all ground leases, deeds
to secure debt, mortgages, restrictive covenants, easements, and other
encumbrances now affecting the Premises, the Project or the Office Park.

                  Section 2.03. Landlord hereby warrants to Tenant that (i) the
Building and (ii) that portion of the Premises to be constructed by Landlord or
Landlord's contractor, will be constructed and operated in a first-class manner,
free of all asbestos containing materials ("ACM") and in full compliance with
all governmental regulations, ordinances, and laws existing at the later of the
time of construction or the execution of this Lease, including, but not limited
to, laws pertaining to disabled access, including the Americans with
Disabilities Act ("ADA"), and laws pertaining to hazardous substances
("Applicable Laws"), in order to make the Premises, the Building and the Land
suitable for business offices. In the case of hazardous substances, the term
"Applicable Laws" will he deemed to include any standards, guidances or other
recommendations issued by nationally recognized authoritative governmental units
or other bodies such as the United States Environmental Protection Agency, the
United States or any relevant state, the Occupational Safety and Health
Administration, the National Institutes of Health or the American Congress of
Industrial Hygienist, Landlord will be fully responsible for making all
alterations and repairs to the Premises and the Building at its cost, which
shall not be included as Operating Costs, resulting from or necessitated by the
failure by Landlord and/or Landlord's Contractor to comply with the Applicable
Laws, or from Landlord's and/or Landlord's Contractor's utilization of hazardous
substances (as deemed by Applicable Laws) at the time the Lease is executed in
violation of Applicable Laws. Landlord's obligation to perform such work in
accordance with Applicable Laws will be deemed to exist on the Commencement Date
and shall be deemed to continue with respect to such Applicable Laws and any
obligation created by such Applicable Laws if the obligation was generally known
on the Commencement Date (and Landlord's obligation shall exist and continue
even though the time for performance under such Applicable Laws was contingent
on (a) the passage of time, (b) the expenditure of money, or (c) the performance
of other work which would trigger such compliance). Landlord shall, subject to
Tenant's repair obligations set forth in the Lease, maintain and operate the
Building in a first class manner, keep the Building Structure (as hereinafter
defined in Section 9.01 ) and the Building Systems (as hereinafter defined in
Section 9.01 ) in first class condition and repair, maintain a safe and
healthful environment in the Building, and operate, maintain, and provide
services and security to, the Building be a first-class manner comparable to
other first-class office buildings in the North Dallas, Texas suburban area
("Comparable Building"), the cost of which (except for capital improvements and
capital repairs, as more specifically hereinafter set forth in Section 5.02)
shall be included in Operating Costs, or paid for directly by Tenant (for
maintenance and repair of the Premises only to the extent required by the Lease)
if not normally included in



                                     - 5 -
<PAGE>   12

Operating Costs. To Landlord's knowledge, the Building contains no friable ACM
and the Building and the restrooms in the Building do not comply with the ADA.
In the event there is discovered friable ACM in the Building and/or the Premises
and such friable ACM shall be required by Applicable Laws to be removed,
Landlord shall, at its sole cost and expense and in accordance with Applicable
Laws, remove the ACM as soon as reasonably practical.

                                    ARTICLE 3

           TERM; COMMENCEMENT DATE DELIVERY AND ACCEPTANCE OF PREMISES

                  Section 3.01. A. The Commencement Date shall be the earlier of
(a) the first (1st) business day of the week following the date Landlord 
delivers to Tenant a written notice stating that the Leasehold Improvements to 
Premises are Substantially Complete and that the Premises are deemed available 
for occupancy pursuant to Section 3.02 hereof, or (b) the date Tenant, or anyone
claiming by, through or under Tenant, occupies any substantial portion of the
Premises for the purpose of the conduct of Tenant's (or such other persons)
business therein. The Commencement Date shall be extended by one (1) day for
each day of delay in the design of, or Tenant's move into, the Premises that is
caused by any Force Majeure (as defined in Section 25.06 hereof) or Landlord
Delay. The terms "Leasehold Improvements," "Substantially Complete," and
"Landlord Delays" are defined in Exhibit "C", attached hereto and made a part
hereof for all purposes.

                           B.  Notwithstanding the provisions of Section 3.01A
hereinabove, Landlord shall cause Landlord's Contractor to complete the
Leasehold Improvements to the Premises within six (6) weeks of commencement of
construction, subject to Force Majeure and Tenant Delay. If the Leasehold
Improvements are not completed subject to the aforementioned delays within eight
(8) weeks of commencement of construction. Tenant shall receive two (2) days of
abated Rent for each day of delay in Substantial Completion of construction. If
the Premises are not Substantially Complete within four (4) months of
commencement of construction, subject to Tenant Delay but regardless of Force
Majeure, Tenant may terminate this Lease if Tenant provides written notice
providing Landlord ten (10) additional days to Substantially Complete the
Premises and Landlord fails to Substantially Complete the Premises within such
ten ( 10) day period.

                  Section 3.02. A. The Premises shall be deemed available for
occupancy as soon as the following conditions have been met: (a) the Leasehold
Improvements (as defined in Exhibit C to the Lease) have been Substantially
Completed (as more particularly defined in Exhibit "C") (b) either a certificate
or certificates of occupancy (temporary or final) or other certificate
permitting the lawful occupancy of the Premises has been issued for the
Premises, by the



                                     - 6 -
<PAGE>   13

appropriate governmental authority; and (c) at least three (3) Business Days'
notice of the anticipated occurrence of the conditions in clauses (a) and (b)
above has been given to Tenant.

                           B.  Notwithstanding anything to the contrary
contained herein, if there is a delay in the availability for occupancy of the
Premises, due to Tenant Delay (as defined in Exhibit C to the Lease) then the
Premises, shall be deemed available for occupancy on the date on which the
Premises, would have been available for occupancy but for such Tenant Delay,
even though a certificate of occupancy or other certificate, permitting the
lawful occupancy of the Premises has not been issued or the Leasehold
Improvements have not been commenced or completed.

                  Section 3.03 The Net Rentable Area of the Premises and the
Building are approximately as stated in Sections 1.011 and J, respectively, and
shall be specifically calculated by the Landlord's architect or space planner
using base building plans in accordance with the definition set forth in Article
27 hereof when the Leasehold Improvements for the Premises are Substantially
Complete. Tenant shall have the right, exercisable within thirty (30) days after
the later of the date Landlord gives Tenant written notice of the final field
measurements of the Premises and the Building or the date Tenant commences
business operations from the Premises (or, when appropriate, any additional
space leased by Tenant pursuant to the Lease), to remeasure the Premises and
Building within such thirty (30) day period. In the event that subsequent
remeasurement of the Premises and/or the Building by Tenant, within the time
period specified above, indicates that the square footage measurement prepared
by Landlord produces a square footage number in excess of or lower than the
square footage number which would have resulted had the measurement been
properly utilized, any payments due to Landlord, from Tenant based upon the
amount of square feet contained in the Premises shall be proportionally,
retroactively and prospectively reduced or increased, as appropriate, to reflect
the actual number of square feet, as properly remeasured. If Landlord disagrees
with Tenant's remeasurement and if a dispute occurs regarding the final accuracy
of such measurements, such dispute will be resolved pursuant to binding
arbitration pursuant to Rider No. 5 ("General Arbitration") hereof. By written
instrument substantially in the form of Exhibit D attached hereto Landlord shall
notify Tenant of the Commencement Date, the Net Rentable Area of the Premises
and all other matters stated therein. The Commencement Notice shall be
conclusive and binding on Landlord and Tenant as to all matters set forth
therein, unless within fifteen (15) days following delivery of such Commencement
Notice. Tenant contests any of the matters contained therein by notifying
Landlord in writing of Tenant's objections. The foregoing notwithstanding,
Landlord's failure to deliver any Commencement Notice to Tenant shall not affect
Landlord's determination of the Commencement Date.




                                     - 7 -
<PAGE>   14

                  Section 3.04. Tenant may not enter or occupy the Premises
prior to the Commencement Date without Landlord's express written consent
(except as otherwise set forth herein) and any entry by Tenant shall be subject
to all of the terms of this Lease; provided however, that no such early entry
shall change the Commencement Date or the Expiration Date. Tenant may enter the
Premises upon receipt of Landlord's consent for the purpose of installing
furniture, special flooring or carpeting, trade fixtures, telephones, computers,
photocopy equipment and other business equipment ("Early Entry Work"). Such
early entry shall not advance the Commencement Date, provided Tenant does not
commence business operations from any part of the Premises. In connection with
such Early Entry Work Landlord shall not be responsible for, and Tenant is
required to obtain insurance covering any loss caused by Tenant or those
entering the Premises on behalf of Tenant to perform such Early Entry Work,
including theft, damage or destruction to any work or material installed or
stored by Tenant or any contractor or individual involved in the construction of
the Leasehold Improvements, or for any injury to Tenant or Tenant's employees,
agents, contractors, licensees, directors, officers, partners, trustees,
visitors or invitees (collectively "Tenant's Employees.") or to any other person
and provided further that such Early Entry Work shall be coordinated with the
activities of the general contractor who is installing the Leasehold
Improvements in the Premises. The Premises will be delivered by Landlord to
Tenant when the Leasehold Improvements are Substantially Complete and the
Premises are ready for occupancy.

                  Section 3.05. Occupancy of the Premises or any portion thereof
by Tenant or .anyone claiming through or under Tenant for the conduct of
Tenant's, or such other person's business therein shall be conclusive evidence
that Tenant and all panics claiming through or under Tenant (a) have accepted
the Premises for the purposes for which the Premises are leased hereunder, (b)
have accepted the Common Areas as being in a good and satisfactory condition and
(c) have waived any defects in the Premises and the Project; provided however,
that, if any Leasehold Improvements have been constructed and installed to
prepare the Premises for Tenant's occupancy. Tenant's acceptance of the
Premises, and waiver of any defect therein, shall occur upon Landlord's
substantial completion of the Leasehold Improvement, in the Premises, or such
portion thereof, in accordance with the terms of Exhibit C hereof, subject only
to Landlord's completion of items on Landlord's punchlists (as determined in
accordance with Exhibit C hereof), latent defects discovered by Tenant and
reported in writing to Landlord within twelve (12) months of the Commencement
Date, and latent defects covered by any contractual warranty, or construction
warranty period provided by Landlord by Landlord's contractor (as defined in
Exhibit C to the Lease).

                  Section 3.06. Tenant's rights and obligations with respect to
extending the Term of this Lease are set forth in Rider No. 2 ("Extension
Option"), attached hereto and made a part of this Lease for all purposes.


                                     - 8 -
<PAGE>   15

                  Section 3.07. Tenant's rights and obligations with respect to
the Must Take Expansion are set forth in Rider No. 3 ("Must Take Expansion"),
attached and made a pan of this Lease for all purposes.

                  Section 3.08. Tenant's right to terminate the Lease prior to
the Expiration Date are set forth in Rider No. 4 ("Right to Terminate Lease"),
attached hereto and made a part of this Lease for all purposes.

                                    ARTICLE 4

                                      RENT

                  Section 4.01. Tenant shall pay to Landlord, without notice,
demand, offset or deduction (except as otherwise provided in the Lease), in
lawful money of the United States of America, at Landlord's Address for Payment,
or at such other place as Landlord shall designate in writing from time to time:
(a) the Base Rent in equal monthly installments, in advance, on the first day of
each calendar month during the Term, and (b) the Additional Rent, at the
respective times required hereunder. The first monthly installment of Base Rent
payable under Article 5 hereof shall be paid on the Commencement Date: provided,
however, that, if either the Commencement Date or the Expiration Date falls on a
date other than the first day of a calendar month, the Rent due for such
fractional month shall be prorated on a per diem basis between Landlord and
Tenant so as to charge Tenant only for the portion of such fractional month
falling within the Term. Notwithstanding the foregoing provisions, Base Rent
shall not commence until thirty (30) days after the Commencement Date ("Rent
Commencement Date"). All installments of Base Rent due for the period from the
Commencement Date through the day prior to the Rent Commencement Date are waived
and abated by Landlord. Any Landlord Delay and/or Force Majeure shall extend the
Rent Commencement by the number of days of such delay.

                  Section 4.02. All past due installments of Rent shall bear
interest until paid at a rate per annum (the "Interest Rate") equal to two
percent (2%) above the prime rate of interest from time to time publicly
announced by The First National Bank of Chicago, a national banking association,
or any successor thereof; provided, however, that, if at the time such interest
is sought to be imposed the rate of interest exceeds the maximum rate permitted
under federal law or under the Laws of the State of Texas, the rate of interest
on such past due installments of Rent shall be the maximum rate of interest then
permitted by applicable law.



                                     - 9 -
<PAGE>   16

                                    ARTICLE 5

                                 OPERATING COSTS

                  Section 5.01. Tenant shall pay to Landlord, as Additional
Rent, for each year or fractional year during the Term, following calendar year
1996, an amount ("Tenant's Operating Costs Payment") of money equal to Tenant's
Share of excess Operating Costs, for such year over Base Year Operating Costs,
such amount to be calculated on a per square foot of NRSF of the Premises basis,
such amount to be calculated and paid as follows:

                  A. On the first day of January of each year during the Term
(or, with respect to the year in which the Commencement Date occurs, prior to
the Commencement Date), or as soon thereafter as is practicable (but at least
within one hundred twenty (120) days after the beginning of each year), Landlord
shall furnish Tenant with a statement setting forth Landlord's reasonable
estimate of Operating Costs, itemized on a line item by line item basis
("Landlord's Operating Costs Estimate") and Tenant's Operating Costs Payment for
the forthcoming year (or the fractional year in which the Commencement Date
occurs, as the case may be). In the event Landlord's Operating Costs Estimate
shall increase in excess of eight percent (8%) over the actual Operating Costs
for the prior year, Landlord shall also furnish Tenant with such backup
information and documentation to substantiate such increase. On the first day of
each calendar month during such year, Tenant shall pay to Landlord one-twelfth
(1/12th) of Tenant's Operating Costs Payment as estimated on Landlord's
Operating Costs Estimate. If for any reason Landlord has not provided Tenant
with Landlord's Operating Costs Estimate on the first day of January of any year
during the Term (or by the Commencement Date, as the case may be), then (a)
until the first day of the calendar month following the month in which Tenant
is given Landlord's Operating Costs Estimate. Tenant shall continue to pay to
Landlord on the first day of each calendar month the sum, if any, payable by
Tenant under this Section 5.01 for the month of December of the preceding year
and, (b) promptly after Landlords' Operating Costs; Estimate is furnished to
Tenant. Landlord shall give notice to Tenant stating whether the installments of
Tenant's Operating Costs Payments previously made for such year were greater or
less than the installments of Tenant's Operating Costs Payments to be made for
such year in accordance with Landlord's Operating Costs Estimate and, and (i) if
there shall be a deficiency, Tenant shall pay the amount thereof to Landlord
within thirty (30) days after the delivery of Landlord's Operating Costs
Estimate, with additional supporting documentation as shall be reasonably
requested by Tenant, or (ii) if there shall have been an overpayment, Landlord
shall apply such overpayment as a credit against the next accruing payments of
Rent due from Tenant under this Lease until fully credited to Tenant, and (iii)
on the first day of the calendar month following the month in which Landlord's
Operating Costs Estimate is given to Tenant and on the first day of each
calendar month throughout the remainder of such year, Tenant shall pay to
Landlord an amount equal to



                                     - 10 -
<PAGE>   17

one-twelfth (1/12th) of Tenant's Operating Costs Payment as shown on Landlord's
Operating Costs Estimate. The foregoing notwithstanding, Landlord shall have the
right from time to time during any year (but not more often than once in any
twelve ( 12) month period) to notify Tenant in writing of any change in
Landlord's Operating Costs Estimate, in which event such Tenant's Operating
Costs Payment, as previously estimated, shall be adjusted to reflect the amount
shown in such notice and shall be effective, and due from Tenant, on the first
day of the month following Landlord's giving of such notice.

                           (b)      Notwithstanding anything to the contrary
contained in Section 5.01A or elsewhere in the Lease, Landlord and Tenant hereby
acknowledge that Tenant shall not be obligated to pay Tenant's Operating Costs
Payment for 50,771 NRSF of the Premises until calendar year 1997.

                  B. On the first day of March of each year during the Term
(beginning on the first day of March of the year following the year in which the
Commencement Date occurs), or as soon thereafter as is practicable, (but at
least within one hundred eighty (180) day after the end of each year) Landlord
shall furnish Tenant with a Statement itemized on a line item by line item basis
showing (i) the amount of the actual Operating Costs for such calendar year and
for the preceding calendar year, (ii) any amount paid by Tenant toward Tenant's
Operating Costs Payments, during such calendar year on an estimated basis and
(iii) any revised estimate of Tenant's obligations for Tenant's Operating Costs
Payment for the current calendar year ("Landlord's Statement"). Within thirty
(30) days after Landlord's giving of such statement, Tenant shall make a lump
sum payment to Landlord in the amount, if any, by which Tenants' Operating Costs
Payment for such preceding year as shown on such Landlord's Statement, exceeds
the aggregate of the monthly installments of Tenant's Operating Costs Payments
paid during such preceding year. If Tenant's Operating Costs Payment, as shown
on such Landlord's Statement, is less than the aggregate of the monthly
installments of Tenant's Operating Costs Payment actually paid by Tenant during
such preceding year, then Landlord shall apply such amount to the next accruing
Rent due from Tenant under this Section 5.01 until fully credited to Tenant. If
the Term shall have expired and no further Rent shall be due, Tenant shall
receive a refund of such difference within thirty (30) days after Landlord sends
the statement of actual Operating Costs. Landlord's failure to provide
Landlord's Statement within twelve ( 12) months of December 31st of any calendar
year shall be deemed a waiver of any right to adjust Tenant's Operating Costs
Payment for such calendar year.

                  C. If the Commencement Date occurs on a date other than the
first day of January, or if the Term ends on a date other than the last day of
December, the actual Operating Costs for the year in which the Commencement Date
or the Expiration Date occurs, as the case may be, shall be prorated to that
Tenant shall pay that portion of Tenant's Share of Operating Costs for such year
represented by a fraction, the numerator of which shall be the number of days
during such



                                     - 11 -
<PAGE>   18
fractional year falling within the Term, and the denominator of which is 365 (or
366, in the case of a leap year). The provisions of this Section 5.01 shall
survive the Expiration Date or any sooner termination provided for in this
Lease.

                  Section 5.02. A. For purposes of this Lease, the term
"Operating Costs" shall mean, subject to the exclusions and the amortization
requirements hereinafter set forth, any and all expenses, costs and
disbursements of every kind which Landlord pays, incurs or becomes obligated to
pay in connection with the operation, management, repair and maintenance of all
portions of the Project. All Operating Costs shall be determined according to
generally accepted accounting principles which shall be consistently applied,
subject to the exclusions and the amortization requirements hereinafter set
forth. Operating Costs include the following: (a) Wages, salaries, and fees
(including all reasonable education, travel and professional fees) of all
personnel or entities at the level of Building manager and below (exclusive of
Landlord's executive personnel) engaged in the operation, repair, maintenance,
or security of the Project, including taxes, insurance, and benefits relating
thereto and the costs of all supplies and materials (including work clothes and
uniforms) used in the operation, repair, maintenance and security of the Project
(provided, however, that if any such employees of Landlord provide services for
more than one building, then a prorated portion of their wages, benefits and
taxes shall be included in Operating Costs based on the portion of their working
time devoted to the Building); (b) Cost of performance by Landlords personnel
of, or of all service agreements for, maintenance, janitorial services, access
control, alarm service, window cleaning, elevator maintenance and landscaping
for the Project. Such cost shall include the rental of personal property used by
Landlord's personnel in the maintenance and repair of the Project; (c) Cost of
utilities for the Project, including water, sewer, power, electricity (including
only electricity and water attributable to the Common Areas of the Building),
gas, fuel, lighting and air-conditioning, heating and ventilating costs
attributable only to the Common Areas of the Building; (d) Cost of all
insurance, including casualty and liability insurance applicable to the Project
and to Landlord's equipment, fixtures and personal property used in connection
therewith, business interruption or rent insurance against such perils as are
commonly insured against by prudent landlords, such other insurance as may be
required by any lessor or mortgagee of Landlord, and such other insurance which
Landlord considers reasonably necessary in the operation of the Project, but in
on event in excess of the types and amount of insurance maintained by comparable
landlords of Comparable Buildings, together with all appraisal and consultants'
fees in connection with such insurance; (e) All Taxes. For purposes hereof, the
term Taxes" shall mean, all taxes, assessments, and other governmental charges,
applicable to or assessed against the project or any portion thereof, or
applicable to or assessed against Landlord's personal property used in
connection therewith, whether federal, state, county, or municipal and whether
assessed by taxing districts or authorities presently taxing the Project or the
operation thereof or by other taxing authorities subsequently created, or
otherwise, and any other taxes and assessments attributable to or assessed
against



                                     - 12 -
<PAGE>   19

all or any part of the Project or its operation; including any reasonable
expenses, including fees and disbursements of attorneys, tax consultants,
arbitrators, appraisers, experts and other witnesses, incurred by Landlord in
contesting any taxes or the assessed valuation of all or any part of the
Project. If at any time during the Term there shall be levied, assessed, or
imposed on Landlord or all or any part of the Project by any governmental entity
any general or special ad valorem or other charge or tax directly upon rents
received under leases, or if any fee, tax, assessment, or other charge is
imposed which is measured by or based, in whole or in part, upon such rents, or
if any charge or tax is made based directly or indirectly upon the transactions
represented by leases or the occupancy or use of the Project or any portion
thereof, such taxes, fees, assessments or other charges shall be deemed to be
Taxes; provided, however, that any (a) franchise, corporation, income or net
profits tax, unless substituted for real estate taxes or imposed as additional
charges in connection with the ownership of the Project, which may be assessed
against Landlord or the Project or both, (b) transfer taxes assessed against
Landlord or the Project or both, (c) penalties or interest on any late payments
of Landlord and, (d) personal property taxes of Tenant or other tenants in the
Project shall be excluded from Taxes. If any or all of the Taxes paid hereunder
are by law permitted to be paid in installments, notwithstanding how Landlord
pays the same, then, for purposes of calculating Operating Costs, such Taxes
shall be deemed to have been divided and paid in the maximum number of
installments permitted by law, and there shall he included in Operating Costs
for each year only such installments as are required by law to be paid within
such year, together with interest thereon and on future such installments as
provided by law; (f) Legal and accounting costs incurred by Landlord or paid by
Landlord to third parties (exclusive of legal fees with respect to disputes with
individual tenants, negotiations of tenant leases, or with respect to the
ownership rather than the operation of the Project), appraisal fees, consulting
fees, all other professional fees and disbursements and all association dues;
(g) Cost of non-capitalized repairs and general maintenance for the Project
(excluding repairs and general maintenance paid by proceeds of insurance or by
Tenant, other tenants of the Project or other third parties); (h) Amortization
of the cost of improvements or equipment which are capital in nature and which
(i) are for the purpose of reducing Operating Costs for the Project, up to the
amount saved as a result of the installation thereof, as reasonably estimated by
Landlord and such savings do not redound primarily to the benefit of any
particular tenant; (ii) are minor capital improvements, tools or expenditures to
the extent each such improvement or acquisition costs less than $5,000 in any
twelve (12) month period; or (iii) are required by any governmental authority
by any new and/or changes in laws, rules, regulations which are enacted after
the Commencement Date. All such costs, including interest thereon, shall be
amortized on a straight-line basis over the useful life of the capital
investment items, as reasonably determined by Landlord; (i) the Project
management office rent or rental value with such management office rent to be
prorated on a per Square foot basis among all buildings managed by the
Building's property manager in Phase I of the Park West Office Community; (j) a
management fee (whether or



                                     - 13 -
<PAGE>   20

not Landlord engages a manager for the Project) and all items reimbursable to
the Project manager, if any, pursuant to any management contract for the
Project. The management fee shall be three percent (3%) of the gross receipts
from the operation of the Project; and (k) amounts payable to Park West One
Association Inc., pursuant to the Declaration, as amended from time to time. It
is understood that Operating Costs shall be reduced by all cash discounts. trade
discounts, or quantity discounts received by Landlord or Landlord's manager in
the purchase of any goods, utilities, or services in connection with the
operation of the Building. Any repair or maintenance costs which are covered by
a warranty or service contract in the base year shall be imputed into the Base
Year Operating Costs. In the event any facilities, services or utilities used in
connection with the Project are provided from another building, the costs
incurred by Landlord in connection therewith shall be allocated to Operating
Costs by Landlord on a reasonably equitable basis. Any operating Costs which are
prorated or allocated between any other buildings in Phase I of the Park West
Office Community, including Operating Costs payable to Park West One
Association, Inc. pursuant to Section 5.02A(C) hereof ("Shared Operating Costs")
shall be prorated based upon the NRSF of such buildings, with the Building's pro
rata portion of such Shared Operating Costs to be no greater than 9.634% of the
total Shared Operating Costs, except for Taxes which, if not separately
determined or allocated by the taxing authority, shall be reasonably determined
by Landlord's independent tax consultant.

                  B. "Operating Costs" shall not include (a) specific costs for
any capital repairs, replacements or improvements, except as provided above; (b)
expenses for which Landlord is reimbursed or indemnified (either by an insurer,
contractor, tenant, warrantor or otherwise) to the extent of funds received by
Landlord; (c) expenses incurred in leasing or procuring tenants (including lease
commissions, advertising expenses and expenses of renovating space for tenants);
(d) payments for rented equipment, the cost of which would constitute a capital
expenditure not permitted pursuant to the foregoing if the equipment were
purchased, except for (i) expenses in connection with making minor repairs on or
keeping Building Systems in operation while minor repairs are being made and
(ii) costs of equipment not affixed to the Project which is used in providing
janitorial or similar services; (e) interest, principal, points and fees on
debts or amortization payments on any mortgages or any other debt instrument;
(f) net basic rents under ground leases; (g) costs representing an amount paid
to an affiliate of Landlord which is in excess of the amount which would have
been paid in the absence of such relationship; (h) costs specially billed to and
paid by specific tenants, (i) costs incurred by Landlord for the repair of
damage to the Project, to the extent that Landlord is reimbursed by insurance
proceeds, and costs of all capital repairs, regardless of whether such repairs
are covered by insurance; (j) costs, including permit, license and inspection
costs, incurred with respect to the installation of tenant or other occupants'
improvements in the Project or incurred in renovating or otherwise improving,
decorating, painting or redecorating vacant space for tenants or other occupants
of the Project; (k) depreciation, amortization and interest



                                     - 14 -
<PAGE>   21

payments, except as provided herein and except on materials, tools, supplies and
vendor-type equipment purchased by Landlord to enable Landlord to supply
services Landlord might otherwise contract for with a third party where such
depreciation, amortization and interest payments would otherwise have been
included in the charge for such third party's services, all as determined in
accordance with generally accepted accounting principles, consistently applied,
and when depreciation or amortization is permitted or required, the item shall
be amortized over its reasonably anticipated useful life; (1) in addition to the
costs set forth in Section 5.02B(c) above, marketing costs, including without
limitation, leasing commissions, attorneys' fees in connection with the
negotiation and preparation of letters, deal memos, letters of intent, leases,
subleases and/or assignments, space planning costs, and other costs and expenses
incurred in connection with lease, sublease and/or assignment negotiations and
transactions with present or prospective tenants or other occupants of the
Project; (m) expenses in connection with services or other benefits which are
not offered to Tenant or for which Tenant is charged for directly but which are
provided to another tenant or occupant of the Project; (n) costs incurred by
Landlord due to the violation by Landlord or any tenant of the terms and
conditions of any lease of space in the Project; (o) Landlord's general
corporate overhead and general and administrative expenses; (p) any compensation
paid to clerks, attendants or other persons in commercial concessions operated
by Landlord or in the Parking Facility of the Project or wherever Tenant is
granted its parking privileges and/or all fees paid to any Parking Facility
operator; (q) advertising and promotional expenditures, and costs of signs in or
on the Project identifying the owner of the Project or other tenants' signs; (r)
services and utilities provided, taxes attributable to, and costs incurred in
connection with the operation of the retail and restaurant operations in the
Project, except to the extent the square footage of such operations are included
in the rentable square feet of the Project and do not exceed the services,
utility and tax costs that would have been incurred had the retail and/or
restaurant space been used for general office purposes; (s) costs incurred in
connection with upgrading the Project to comply with life, fire and safety
codes, ordinances, statutes or other laws in effect prior to the Commencement
Date, (excluding costs to cause the Premises to comply with the Americans with
Disabilities Act ("ADA") which shall be solely borne by Tenant), including,
without limitation, the ADA, (but solely as to the Common Areas of the Project),
including penalties or damages incurred due to such non-compliance; (t) tax
penalties incurred as a result of Landlord's negligence, inability or
unwillingness to make payments and/or to file any tax or informational returns
when due and any other late charges, penalties or fees paid by Landlord to any
entity, as well as any premium or overtime charges which were unnecessary or
which could have been avoided if Landlord had acted in a timely manner; (u)
costs for which Landlord has been compensated by a management fee; (v) costs
arising from the negligence or fault of other tenants or Landlord or its agents,
or any vendors, contractors, or providers of materials or services selected,
hired or engaged by Landlord or its agents including, without limitation, the
selection of Project materials; (w) notwithstanding any contrary provision of
the Lease, including,




                                     - 15 -
<PAGE>   22

without limitation, any provision relating to capital expenditures, any and all
costs arising from the presence of hazardous materials or substances (as defined
by Applicable Laws in effect on the date this Lease is executed) in or about the
Premises, the Project or the Land including, without limitation. hazardous
substances in the ground water or soil, not placed in the Premises, the Project
or the Land by Tenant; (x) costs arising from Landlord's charitable or political
contributions; (y) costs arising from latent defects in the base, shell or core
of the Project or improvements installed by Landlord or repair thereof, which
are reported to Landlord in writing within twelve (12) months of the
Commencement Date; (z) costs arising from any mandatory or voluntary special
assessment on the Project or the Land by any transit district authority or any
other governmental entity having the authority to impose such assessment; (aa)
costs for sculpture, paintings or other objects of art; (bb) costs (including in
connection therewith all attorneys' fees and costs of settlement judgments and
payments in lieu thereof) arising from claims, disputes or potential disputes in
connection with potential or actual claims litigation or arbitrations pertaining
to Landlord and/or the Project and/or the Land; (cc) costs associated with the
operation of the business of the partnership or entity which constitutes
Landlord as the same are distinguished from the costs of operation of the
Project, including partnership accounting and legal matters, costs of defending
any lawsuits with any mortgagee (except as the actions of Tenant may be in
issue), costs of selling, syndicating, financing, mortgaging or hypothecating
any of Landlord's interest in the Project, costs of any disputes between
Landlord and its employees (if any) not engaged in Project operation, disputes
of Landlord with Project management, or outside fees paid in connection with
disputes with other tenants; (dd) costs of any "tap fees" or any sewer or water
connection fees for the benefit of any particular tenant (as opposed to all of
the tenants) in the Project; (ee) costs incurred in connection with any
environmental clean-up, response action, or remediation on, in, under or about
the Premises or the Project, including but not limited to, costs and expenses
associated with the defense, administration, settlement, monitoring or
management thereof; (ff) any expenses incurred by Landlord for use of any
portions of the Project to accommodate events including, but not limited to
shows, promotions, kiosks, displays, filming, photography, private events or
parties, ceremonies, and advertising beyond the normal expenses otherwise
attributable to providing Project services, such as lighting and HVAC to such
public portions of the Project in normal Project operations during standard
Project hours of operation; (gg) any "validated" parking for any entity; and
(hh) any "above-standard" cleaning, including, but not limited to construction
cleanup or special cleanings associated with parties/events and specific tenant
requirements in excess of service provided to Tenant, including related trash
collection, removal, hauling and dumping. There shall be no duplication of costs
or reimbursements.

                  C. Notwithstanding anything to the contrary contained in this
Section 5.02 or elsewhere in the Lease, for purposes of calculating Tenant's
Operating Costs Payment for the period beginning January 1, 1997, and for each
year thereafter for the remainder of the initial Term, the components of
Operating

                                     - 16 -
<PAGE>   23

Costs set forth in Sections 5.02A (a), (b), (f), (g), (h), (i), and (j)
(collectively "Controllable Operating Costs") shall not he annually increased by
more than eight percent (8%) for the remaining years of initial Term over the
actual 1996 "grossed up" Controllable Operating Costs, as determined in the
aggregate, on a compounded basis.

                  Section 5.03. If the Building is not fully occupied (meaning
ninety-five percent (95%) of the Net Rentable Area of the Building) during any
full or fractional year of the Term (including the Base Year), the actual
Operating Costs for such period shall be deemed to be equal to the total of the
Operating Costs which would have been incurred by Landlord if 95% of the Net
Rentable Area of the Building had been occupied for the entirety of such period.
Notwithstanding the foregoing, Landlord shall not recover as Operating Costs
more than one hundred percent (100%) of the Operating Costs actually paid by
Landlord. Operating Costs shall be computed according to accrual basis of
accounting. in accordance with standard and reasonable accounting principles
employed by Landlord.

                  Section 5.04. If during the Term any change occurs in either
the number of square feet of the Net Rentable Area of the Premises or of the Net
Rentable Area of the Building, Tenant's Share of Operating Costs shall be
adjusted, effective as of the date of any such change. Landlord shall promptly
notify Tenant in writing of such change and the reason therefor. Any changes
made pursuant to this Section 5.04 shall not alter the computation of Operating
Costs as provided in this Article 5, but, on and after the date of any such
change, Tenant's Operating Costs Payment pursuant to Section 5.01A shall be
computed upon Tenant's Share thereof, as adjusted. If such estimated payments of
Tenant's Share are so adjusted during a year, a reconciliation payment for
Tenant's Share of Operating Costs pursuant to this Article 5 for the calendar
year in which such change occurs shall be computed pursuant to the method set
forth in Section 5.01 B.

                  Section 5.05. Tenant shall, at Tenant's sole cost and expense,
have the right, at anytime with reasonable cause, upon reasonable written
notice, during the business hours of Landlord and in a manner so as to not
unreasonably interfere with Landlord's business, to have a certified public
accountant, audit Landlord's books related to the computation of Operating
Costs. Such audit may cover a period of time up to three (3) years prior to the
date of such audit. If Landlord and Tenant mutually agree upon any
misapplication of miscalculation of Operating Costs, or if Tenant finds a credit
owed by Landlord, then Landlord shall adjust its Operating Costs computation and
pay Tenant for such adjustment within thirty (30) days of Landlord agreeing to
the adjustment. If the audit reveals an overpayment of Operating Costs by Tenant
in excess of five percent (5%), and if Landlord agrees with such audit, then
Landlord shall additionally reimburse Tenant for the reasonable costs of such
audit. If Landlord disagrees with such audit, Landlord shall advise Tenant in
writing within thirty (30) days of Landlord's receipt of such audit and Tenant
shall have the right to submit the audit dispute to

                                     - 17 -
<PAGE>   24

arbitration pursuant to Rider No. 5 ("General Arbitration") within five (5) days
of receipt of the results of Landlord s written notice disputing such audit.
Landlord hereby acknowledges that nothing in this Section 5.05 shall prohibit
Tenant from auditing Landlord's books related to the computation of Operating
Costs utilizing Tenant's internal staff. The arbitration shall be final and
binding upon Landlord and Tenant. Tenant agrees to pay the cost of such audit,
provided that, if the arbitration determines that Landlord's determination of
Tenant's Operating Costs Payment as set forth in any statement sent to Tenant
was in error in Landlord's favor by more than five percent (5%). Landlord shall
pay the cost of such audit. Landlord shall be required to maintain records of
all Operating Costs and other Rent adjustments for the entirety of the
three-year period ("Review Period") following Landlord's delivery to Tenant of
each statement setting forth Tenant's Operating Costs Payment. The payment by
Tenant of any amounts pursuant to this Article 5 shall not preclude Tenant from
questioning the correctness of any statement provided by Landlord at any time
during the Review Period, but the failure of Tenant to object thereto prior to
the expiration of the Review Period shall be conclusively deemed Tenant's
approval of the statement.

                                    ARTICLE 6

                                     PARKING

                  Section 6.01. Landlord shall maintain and operate, or cause to
be maintained and operated, an area for automobile parking in the Parking
Facility. Landlord hereby grants to Tenant the right to use in common with
tenants in the buildings in Phase I of the Park West Office Community and with
the public the Parking Facility and shall issue Parking Permits for such use.
Each such Parking Permit shall entitle Tenant to one (1) unassigned parking
space in the Parking Facility. The number of Parking Permits to be issued to
Tenant is set forth in Section 1.01P. At any time and from time to time during
the Term of this Lease, Tenant may decrease or increase the number of Parking
Permits up to the maximum permitted in Section 1.01(P) by giving thirty (30)
days' written notice to Landlord. Landlord shall not be obligated to provide
Tenant with any additional Parking Permits. Tenant shall at all times observe
Landlord's reasonable Rules and Regulations with respect to the Parking
Facility; provided, however, that Tenant shall always have the right to use the
Parking Facility twenty-four (24) hours a day, seven ( 7) days a week, every day
of the year.

                  Section 6.02 If all or any portion of the Parking Facilities
shall be damaged or rendered unusable by fire or other casualty or any taking
pursuant to eminent domain proceeding (or deed in lieu thereof), and as a result
thereof Landlord or the garage operator is unable to make available to Tenant
the parking provided for herein, then in any such instance, Landlord shall use
all reasonable efforts to provide adequate substitute parking reasonably
satisfactory to Tenant,

                                     - 18 -
<PAGE>   25

which parking area may be surface parking, located in the general vicinity of
the Building. If Landlord is unable to provide suitable substitute parking
located in the general vicinity of the Building within forty-five (45) days of
such condemnation or casualty, Tenant may, at any time thereafter, up to thirty
(30) days written notice to Landlord, terminate the Lease.

                  Section 6.03.   Visitor parking shall be at no charge and in
common with other parkers in the Parking Facility.


                                    ARTICLE 7

                              SERVICES OF LANDLORD

                  Section 7.01. A. During the Term, Landlord shall furnish
Tenant with the following services: (a) hot and cold water in Building Standard
bathrooms and chilled water in Building Standard drinking fountains; (b)
electrical power sufficient for lighting the Premises and for the operation
therein of typewriters, voicewriters, calculating machines, word processing
equipment, photographic reproduction equipment, copying machines, personal
computers, and similar items of business equipment which consume, in the
aggregate, less than seven (7) watts per square foot of Net Rentable Area of the
Premises and require a voltage of one hundred twenty/two hundred seventy seven
(120/277) volts. Landlord hereby advises Tenant that Landlord can provide
electric capacity (not including base Building central HVAC) of at least six (6)
watts per square foot of Net Rentable Area within the Premises, however, Tenant,
at its sole cost and expense, shall be obligated for any cost associated with
providing excess capacity over five (5) watts per square foot of Net Rentable
Area (it being understood. however, that Tenant shall only be responsible for
the cost of electrical distribution devices and distribution on the particular
floor of the Premises where such additional electrical capacity shall be
required) (c) heating, ventilating or air-conditioning, twenty-four (24) hours
per day. seven (7) days per week, at such temperatures and in such amounts as
customarily and seasonally provided to tenants occupying comparable space in
first-class office buildings in the North Dallas suburban area for general
office purposes, but with respect to Tenant's equipment room, Tenant will
provide, at its sole cost and expense, any supplemental HVAC unit required to
provide air-conditioning to such equipment room on a 24 hour basis; (d) electric
lighting for the Common Areas of the Project; (e) passenger elevator service, in
common with others, for access to and from the Premises twenty-four (24) hours
per day, seven (7) day per week; provided, however, that Landlord shall have the
right to limit the number of (but not cease to operate all) elevators to be
operated after Business Hours and on Saturdays, Sundays and Holidays; (f)
janitorial cleaning services as reasonably determined by Landlord but which is
at least comparable to such services as provided in Comparable Buildings, and;
(g) facilities for Tenant's loading, unloading, delivery and pick-up activities,


                                     - 19 -
<PAGE>   26

including access thereto during Business Hours, subject to the Rules and
Regulations, the type of facilities, and other limitations of such loading
facilities; (h) replacement, as necessary, of all Building Standard lamps and
ballasts in Building Standard light fixtures within the Premises; and (i)
security at least comparable to the security being provided in Comparable
Buildings. Tenant shall be entitled, at Tenant's sole cost, to install its own
security system for the Premises, which shall be located within the Premises and
shall not interfere with the Building Systems, subject to Landlord's reasonable
approval, which approval may be conditioned upon Tenant agreeing to remove the
security system to repair the damage caused by such removal, and to return the
portion of the Premises affected by such removal to Landlord in the condition
such portion of the Premises was delivered to Tenant. All services referred to
in this Section 7.01 A shall be provided by Landlord and paid for by Tenant as
part of Tenant's Operating Costs Payment; provided, however, that the cost for
Tenant's use of electric power shall be paid by Tenant directly to the utility
company providing such electric power, if allowed by such utility company, and
shall not be included in Operating Costs.

                  B. Tenant shall have the right to control, without Landlord's
consent, the after hours HVAC serving the Premises through thermostats or
similar controls located within the Premises. The cost of after hour, HVAC
services shall be equal to the actual charges of the utility company providing
such electric power, without mark-up and without a fee to Landlord's Manager. If
Tenant requires other services (other than electricity and HVAC), including
cleaning services, routinely supplied by Landlord for hours or days in addition
to the hours and days specified in Section 7.01A, Landlord shall, to the extent
same can be provided by the Building Systems, provide such additional service
after prior request therefor of no less than five (5) business hours advance
notice to Landlord's Building management from an authorized representative of
Tenant, and Tenant shall reimburse Landlord for the actual, reasonable and
documented out-of-pocket incremental extra cost to Landlord to provide which
additional services, without markup for profit or overhead, but including
depreciation costs, if any, and a three percent (3%) fee to Landlord's manager,
if Landlord's manager renders any services in connection with providing such
additional HVAC services ("Actual Cost") within thirty (30) days following
receipt by Tenant of invoice therefor and reasonable additional supporting
documentation requested by Tenant; provided however, that, if any other tenants
in the Building served by the equipment providing such additional service to the
Premises request that Landlord concurrently provide such service to such other
tenants, the cost of Landlord's providing such additional and concurrent service
shall be prorated among all of the tenants requesting such service. If any
machinery or equipment which generates abnormal heat or otherwise creates
unusual demands on the air-conditioning or heating system serving the Premises
is used in the Premises and if Tenant has not, within five (5) days after demand
from Landlord, taken such steps, at Tenant's expense, as shall be necessary to
cease such adverse affect on the air-conditioning or heating system, Landlord
shall have the right to install supplemental air-conditioning or heating



                                     - 20 -
<PAGE>   27

units in the Premises, and the full cost of such supplemental units (including
the cost of acquisition, installation, operation, use and maintenance thereof)
shall be paid by Tenant to Landlord within thirty (30) of receipt by Tenant of
written invoice therefor and supporting documentation requested by Tenant.
Landlord agrees to advise Tenant whether any equipment and machinery
contemplated by Tenant to be used herein will not generate abnormal heat or
create unusual demands on the HVAC system serving the Premises, provided that
Tenant provides Landlord a listing of which proposed equipment prior to Tenant's
Occupancy of the Premises. During the Term, Tenant may replace and add similar
types of equipment which require similar wiring for installation, with similar
electrical consumption, without Landlord's consent and any such similar
equipment shall not he deemed to generate abnormal heat or create unusual HVAC
demands.

                  C. The degree of electrical and water consumption by Tenant
shall be determined by a separate meter in the Premises to be installed and
maintained by Landlord, all at Tenant's sole cost and expense. Landlord
acknowledges that the Premises are currently separately metered, but Tenant
shall bear all costs for any additional meters, if any. Tenant shall not install
any electrical equipment requiring special wiring unless reasonably approved in
advance by Landlord. At no time shall use of electricity in the Premises exceed
the capacity of existing feeders and risers to or wiring in the Premises. Any
risers or wiring to meet Tenant's excess electrical requirements shall, upon
Tenant's written request and at Tenant's option, be installed by Landlord, at
Tenant's sole cost, if, in Landlord's reasonable judgment, the same are
necessary and shall not (i) cause permanent damage or injury to the Project, the
Building or the Premises, (ii) cause or create a dangerous or hazardous
condition, or (iii) entail excessive or unreasonable alterations, repairs or
expenses.

                  Section 7.02. Landlord's obligation to furnish electrical and
other utility services shall be subject to the rules and regulations of the
supplier of such electricity of other utility services and the rules and
regulations of any municipal or other governmental authority regulating the
business of providing electricity .and other utility services. Landlord shall
make all necessary arrangements with the public utility supplying electric or
other utility service directly to the Building to cause the electric or other
utility service provider to bill Tenant directly for such utility services,
unless prohibited by law or regulations of such public utility. Tenant shall,
however, be responsible for contracting promptly and directly with such public
utility supplying such service and for paying all deposits for, and all costs
relating to, such service.

                  Section 7.03. Except as otherwise set forth herein, failure to
furnish, or any stoppage of, the services referred to in this Article 7
resulting from any cause shall make Landlord liable in any respect for damages
to any person, property or business, or be construed as an eviction of Tenant,
or entitle Tenant to any abatement of Rent or other relief from any of Tenant's
obligations under this



                                     - 21 -
<PAGE>   28

Lease. Should any malfunction of any systems or facilities occur within the
Project or should maintenance or alterations of such systems or facilities
become necessary, Landlord shall repair the same promptly and with reasonable
diligence, and Tenant shall have no claim for rebate, abatement of Rent, or
damages because of malfunctions or any such interruptions in service. In the
event that Tenant is prevented from using, and does not use, the Premises, or
any portion thereof, for three (3) consecutive business days or ten (10)
business days in any twelve (12) month period (the "Eligibility Period") as a
result of (i) any damage or destruction to the Premises, the Parking Facility
and/or the Building, (ii) any repair, maintenance or alteration performed by
Landlord after the Commencement Date and required by the Lease, which materially
and adversely interferes with Tenant's use of the Premises, the Parking Facility
and/or the Building, (iii) any failure by Landlord to provide Tenant with
services or access to the Premises, the Parking Facility and/or the Building,
(iv) because of an eminent domain proceeding or (v) because of the presence of
hazardous substances in, on or around the Premises, the Building or the Land
which could pose a health risk to occupants of the Premises, then Tenant's Rent
shall be equitably abated after expiration of the Eligibility Period for such
time that Tenant continues to be so prevented from using, and does not use, the
Premises or a portion thereof, in the proportion that the Net Rentable Area of
the portion of the Premises that Tenant is prevented from using, and does not
use, bears to the total Net Rentable Area of the Premises. However, in the event
that Tenant is prevented from conducting, and does not conduct, its business in
any portion of the Premises for a period of time in excess of the Eligibility
Period, and the remaining portion of the Premises is not sufficient to allow
Tenant to effectively conduct its business therein, and if Tenant does not
conduct its business from such remaining portion, then for such time after
expiration of the Eligibility Period during which Tenant is so prevented from
effectively conducting its business therein, and Tenant does not conduct
Tenant's business from such remaining portion of the Premises, the Rent for the
entire Premises shall be duly abated; provided, however, if Tenant reoccupies
and conducts its business from any portion of the Premises during such period,
the Rent allocable to such reoccupied portion, based on the proportion that the
Net Rentable Area of such reoccupied portion of the Premises bears to the total
Net Rentable Area of the Premises, shall be payable by Tenant from the date such
business operations commence. If Tenant's right to abatement occurs because of
an eminent domain taking and/or because of damage or destruction to the
Premises, the Parking Facility, and/or the Building, Tenant's abatement period
shall continue until Tenant has been given sufficient time, and sufficient
access to the Premises, the Parking Facility and/or the Building, to rebuild
such portion it is required to rebuild, including insufficient time to install
Tenant's Property (as defined in Section 14.01 hereof) to the extent the same
shall have been removed as a result of such damage or destruction and to move in
over a weekend. To the extent Tenant is entitled to abatement without regard to
the Eligibility Period, because of an event covered by Articles 15 and 16 of the
Lease, then the Eligibility Period shall not be applicable.


                                     - 22 -
<PAGE>   29
                                    ARTICLE 8

                            ASSIGNMENT AND SUBLETTING

                  Section 8.01. Except as otherwise provided in this Article 8,
neither Tenant nor its legal representatives or successors in interest shall, by
operation of law or otherwise, assign, mortgage, pledge, encumber or otherwise
transfer this Lease or any part hereof, or the interest of Tenant under this
Lease, or in any sublease or the rent thereunder. The Premises or any part
thereof shall not be sublet, occupied or used for any purpose by anyone other
than Tenant, without Tenant's obtaining in each instance the prior written
consent of Landlord, which consent shall not be unreasonably withheld or
delayed. Tenant shall not modify, extend, or amend a sublease previously
consented to by Landlord without obtaining Landlord's prior written consent
thereto, which consent shall not be unreasonably withheld or delayed.

                  Section 8.02. Notwithstanding anything to the contrary in
Section 8.01, Tenant shall have the right, without the necessity of obtaining
Landlord's prior approval thereof, but upon ten (10) days' prior written notice
to Landlord, to (a) assign this Lease or sublet all or part of the Premises to
any related corporation or other entity which controls, directly or indirectly,
Tenant, is controlled, directly or indirectly, by Tenant or is under common
control with Tenant; or (b) assign this Lease or subleases the Premises to a
successor corporation into which or with which Tenant is merged or consolidated
or which acquired substantially all of Tenant's assets and property or which is
acquired, in whole or in part, by Tenant; provided that (i) such successor
corporation assumes substantially all of the obligations and liabilities of
Tenant and shall have assets, capitalization and net worth at least equal to the
assets, capitalization and net worth of Tenant and the assignee or sublessee as
of the date of this Lease as determined by generally accepted accounting
principles, and (ii) Tenant shall provide in its notice to Landlord the
information required in Section 8.03. For the purpose hereof "control" shall
mean ownership of not less than 50% of all the voting stock or legal and
equitable interest in such corporation or entity.

                  Section 8.03. If Tenant should desire to assign this Lease or
sublet the Premises (or any part thereof), Tenant shall give Landlord written
notice no later than the time required for notice under Section 8.02 in the case
of an assignment or subletting, or thirty (30) days in advance of the proposed
effective date of any other proposed assignment or sublease, specifying (a) the
name, current address, and business of the proposed assignee or sublessee, (b)
the amount and location of the space within the Premises proposed to be so
subleased, (c) the proposed effective date and duration of the assignment or
subletting, and (d) the proposed rent or consideration to be paid to Tenant by
such assignee or sublessee. Tenant shall promptly supply Landlord with financial
statements and other information as Landlord may reasonably request to evaluate
the proposed

                                     - 23 -
<PAGE>   30

assignment or sublease. For assignments and sublettings other than those
permitted by Section 8.02, Landlord shall have fifteen (15) days following
receipt of such notice and other information requested by Landlord within which
to notify Tenant in writing that Landlord elects: (i) to permit Tenant to assign
or sublet such space; provided, however, that Tenant shall pay Landlord, as
Additional Rent, fifty percent (50%) of any Profits (as defined below) actually
received by Tenant pursuant to such approved assignment or sublease. Whenever
Landlord is entitled to share in any excess income resulting from an assignment
or sublease of the Premises, the following shall constitute the definition of
"Profits": the gross revenue received from the assignee or sublessee during the
sublease term or during the assignment, with respect to the space covered by the
sublease or the assignment ("Transferred Space") less: (a) the gross revenue
paid to Landlord by Tenant during the period of the sublease term or during the
assignment with respect to the Transferred Space; (b) any improvement allowance
or other economic concession (planning allowance, moving expenses, etc.), paid
by Tenant to sublessee or assignee; (c) brokers' commissions; (d) attorneys'
fees; (e) lease takeover payments; (f) costs of advertising the space for
sublease or assignment; (g) unamortized cost of initial and subsequent
improvements to the Premises by Tenant; and (h) any other costs actually paid in
assigning or subletting the Transferred Space; provided, however, under no
circumstance shall Landlord be paid any Profits until Tenant has recovered all
the items set forth in subparts (a) through (h) for such Transferred Space, it
being understood that if in any year the gross revenues, less the deductions set
forth in subparts (a) through (h) above (the "Net Revenues"), are less than any
and all costs actually paid in assigning or subletting the affected space
(collectively "Transaction Costs"), the amount of the excess Transaction Costs
shall be carried over to the next year and then deducted from Net Revenues with
the procedure repeated until a Profit is achieved; or (ii) to refuse, in
Landlord's reasonable discretion, to consent to Tenant's assignment or
subleasing of such space and to continue this Lease in full force and effect as
to the entire Premises. The parties agree that Landlord may, subject to the
remainder of the sentence, reasonably refuse to consent to an assignment or
subletting if the proposed assignee or subtenant is not financially creditworthy
to undertake the obligations imposed by the assignment or sublease, is a
governmental authority or agency, an organization or person enjoying sovereign
or diplomatic immunity, a medical or dental practice or a user that will attract
a volume, frequency or type of visitor or employee to the Building which is not
consistent with the standards of a high quality office building or that will
impose an excessive demand on or use of the facilities or services of the
Building, but that it shall be unreasonable for Landlord to refuse its consent
to an assignment or sublease to any assignee or sublessee that is comparable in
quality to other tenants in the Building or Comparable Buildings and that will
use the Premises in a manner generally comparable to the use of comparable space
in the Building or Comparable Buildings or, if there is common ownership between
the owner of the building located at 1605 LBJ Freeway, Dallas, Texas and the
Building, disapproving any use or type of tenant that leases space in the 1605
LBJ Freeway, Dallas, Texas building. It shall also be reasonable for Landlord to
refuse to consent



                                     - 24 -
<PAGE>   31

to any assignment or subletting if (i) an Event of Default has occurred under
this Lease with any applicable cure period having expired, or (ii) such
assignment of subletting would cause a default by Landlord under another lease
in the Building or under any ground lease, deed of trust, mortgage, restrictive
covenant, easement or other encumbrance affecting the Project. If Landlord
should fail to notify Tenant in writing of such election within the aforesaid
fifteen (15) day period, Landlord shall be deemed to have elected option (ii)
above, but if Tenant advises Landlord in writing of such failure to respond and
Landlord does not respond within an additional five (5) business day period
after Landlord's receipt of such notice, then Landlord shall be deemed to have
elected option (i) above. Tenant agrees to reimburse Landlord for legal fees and
any other reasonable costs incurred by Landlord in connection with any permitted
assignment or subletting the aggregate of which shall in no event exceed $500.00
per requested assignment or sublease, and such payment shall not be deducted
from the Additional Rent owed to Landlord pursuant to subsection (i) above.
Tenant shall deliver to Landlord copies of all documents executed in connection
with any permitted assignment or subletting, which documents shall be in form
and substance reasonably satisfactory to Landlord and which shall require any
assignee to assume performance of all terms of this Lease to be performed by
Tenant or any subtenant to comply with all the terms of this Lease to be
performed by Tenant with respect to the sublease Premises. No acceptance by
Landlord of any Rent or any other sum of money from any assignee, sublessee or
other category of transferee shall be deemed to constitute Landlord's consent to
any assignment, sublease, or transfer.

                  Section 8.04. Any attempted assignment or sublease by Tenant
in violation of the terms and provisions of this Article 8 shall be void and
shall, if not cured within the applicable notice and cure period, constitute a
material breach of this Lease. In no event shall any assignment, subletting or
transfer, whether or not with Landlord's consent, relieve Tenant of its primary
liability under this Lease for the entire Term, and Tenant shall in no way be
released from the full and complete performance of all the terms hereof. If
Landlord takes possession of the Premises before the expiration of the Term of
this Lease pursuant to an Event of Default by Tenant and the failure of Tenant
to cure such Event of Default within the applicable cure period, Landlord shall
have the right, at its option, to terminate all subleases (subject to the
provisions of this Section 8.07), or to take over any sublease of the Premises
or any portion thereof and such subtenant shall attorn to Landlord, as its
landlord, under all the terms and obligations of such sublease occurring from
and after such date, but excluding previous acts, omissions, negligence or
defaults of Tenant and any repair or obligation in excess of available net
insurance proceeds or condemnation award.

                  Section 8.05. The term "Landlord", as used in this Lease, so
far as covenants or obligations on the part of Landlord are concerned, shall be
limited to and include only the owner or owners, at the time in question, of the
fee title to, or a lessee's interest in a ground lease of, the Land or the
Building. In the event of any



                                     - 25 -
<PAGE>   32

transfer, assignment or other conveyance or transfers of any such title or
interest, Landlord herein named (and in case of any subsequent transfers of any
such title or interest, Landlord herein named (and in case of any subsequent
transfers or conveyances, the then grantor) shall, upon written notice to Tenant
advising Tenant of such transfer, be automatically freed and relieved from and
after the date of such transfer, assignment or conveyance of all liability as
respects the performance of any covenants or obligations on the part of Landlord
contained in this Lease thereafter to be performed and, without further
agreement, the transferee of such title or interest shall be deemed to have
assumed and agreed to observe and perform any and all obligations of Landlord
hereunder, during its ownership of the Project. Landlord may transfer its
interest in the Project without the consent of Tenant and such transfer or
subsequent transfer shall not be deemed a violation on Landlord's part of any of
the terms of this Lease.

                  Section 8.06. Tenant may allow any person or company which is
a client or customer of Tenant or which is providing service to Tenant or one of
Tenant's clients to occupy certain portions of the Premises without such
occupancy being deemed an assignment or subleasing as long as no new demising
walls are constructed to accomplish such occupancy and as long as such
relationship was not created as a subterfuge to avoid the obligations set forth
in this Article 8.

                  Section 8.07. To the extent that Tenant enters into an
assignment of the Lease or enters into a sublease for all or any portion of the
Premises equal to or in excess of one ( 1 ) floor of the Building, Landlord, if
it grants its consent to such assignment or sublease, which consent shall not be
unreasonably withheld, conditioned or delayed, shall also simultaneously
reasonably consider executing and delivering a recognition agreement pursuant to
which Landlord shall agree that in the event Tenant defaults under the Lease,
the assignment or the sublease shall be recognized as a direct lease between
Landlord and the assignee or the subtenant on the terms and conditions of the
assignment or sublease, with Landlord's consideration to take into account,
amongst other things, the rent being paid by any sublessee, the creditworthiness
of any sublessee or assignee, and the term of the sublease or assignment.

                                    ARTICLE 9

                                     REPAIRS

                  Section 9.01. Landlord agrees that at all times it will
maintain the structural portions of the Building, including the foundation,
floor/ceiling slabs, roof, curtain wall, exterior glass and mullions, columns,
beams, shafts (including elevator shafts), stairs, Parking Facility,
stairwells, escalators, elevator cabs, plazas, art work, sculptures, washrooms,
mechanical, electrical and telephone closets, and all Common Areas and public
areas (collectively, "Building Structure.)



                                     - 26 -
<PAGE>   33

and the mechanical, electrical, life safety, plumbing, sprinkler systems
(connected to the core) and HVAC systems (-Building Systems-) in good condition
and repair. Notwithstanding anything in this Lease to the contrary, Tenant shall
not be required to make any repair to, modification of, or addition to the
Building Structure and/or the Building Systems except and to the extent required
because of Tenant's use of the Premises for other than normal and customary
business office operations. Except for ordinary wear and tear and casualty,
except as otherwise provided in Section 9.02, and except for cosmetic and other
nominal repairs of $5,000.00 or less which do not affect the Building Systems or
Building Structure ("Minor Repairs"), which Minor Repairs Tenant may elect to
complete, Landlord shall perform any maintenance and make all repairs and
replacements to the Premises (including the Leasehold improvements). Except to
the extent already included in Operating Costs, Tenant shall pay to Landlord the
Actual Cost for (a) all maintenance, repairs and replacements within the
Premises (including the Leasehold Improvements,) other than (i) repairs and
replacements necessitated by the willful misconduct or negligence of Landlord or
its agents, employees, contractors, invitees or licensees to the extent the cost
thereof is not covered and corrected under Tenant's insurance, or, if Tenant is
not carrying all of the insurance described in Section 14.01A, to the extent
such cost would not be covered by the insurance described in Section 14.01A, if
the same were in effect, and (ii) maintenance, repairs and replacements of the
Building Structure or Building Systems; (b) all repairs and replacements
necessitated by damage to the Project (including the Building Structure and the
Building Systems within the Premises) caused by the negligence or willful
misconduct of Tenant or its agents, contractors, invitees and licensees but only
to the extent the cost thereof is not covered and collected under Landlord's
insurance, or, if Landlord is not carrying all of the insurance described in
Section 14.02, to the extent that such cost would not be covered by the
insurance described in Section 14.02 if the same were in effect. Amounts payable
by Tenant pursuant to this Section 9.01 shall be payable within thirty (30) days
after receipt of an invoice therefor from Landlord and additional supporting
documentation reasonably requested by Tenant. Landlord has no obligation and has
made no promise to maintain, alter, remodel, improve, repair, decorate, or paint
the Premises or any part thereof, except as specifically set forth in this
Lease. In no event shall Landlord have any obligation to maintain, repair or
replace any furniture, furnishings, fixtures or personal property of Tenant,
except as may be due to the negligence or willful misconduct of Landlord or
agents, contractors, and licensees and to the extent not covered and collected
under Tenant's insurance.

                  Section 9.02. Tenant shall keep the non-structural portion of
the Premises (including the Leasehold Improvements) in good order and in a safe,
neat and clean condition. No representations respecting the condition of the
Premises or the Building or the other portions of the Project have been made by
Landlord to Tenant except as specifically set forth in this Lease. Except as
provided in Section 9.01 and Section 10.01 or specifically consented to by
Landlord, Tenant shall not



                                     - 27 -
<PAGE>   34

perform any maintenance or repair work or make any replacement in or to the
Premises (including the Leasehold Improvements) but rather shall promptly notify
Landlord of the need for such maintenance, repair or replacement so that
Landlord may proceed to perform the same pursuant to the provisions of Section
9.01. In the event Landlord specifically consents to the performance of any
maintenance or the making of any repairs or replacements by Tenant and Tenant
fails to promptly commence and diligently pursue the performance of such
maintenance or the making of such repairs or replacements which are the
responsibility of Tenant, then Landlord, at its option pursuant to written
notice hereof to Tenant and failure of Tenant within thirty (30) days of receipt
of such notice to commence such maintenance or repair, may perform such
maintenance or make such repairs and Tenant shall reimburse Landlord, within
thirty (30) days after Tenant receives an invoice therefor, the Actual Cost
thereof.

                  Section 9.03. All repairs made by Tenant pursuant to Section
9.02 shall be performed in a good and workmanlike manner by contractors or other
repair personnel selected by Tenant from an approved list of contractors and
repair personnel maintained by Landlord in the management office or repair
personnel otherwise reasonably approved by Landlord: provided. however, that
neither Tenant nor its contractors or repair personnel shall be permitted to do
any work affecting the Building Structure or the Building Systems (except as
otherwise set forth in Section 9.05). In no event shall such work be done for
Landlord's account or in a manner which allows any liens to be filed in
violation of Article 11, To the extent any repairs involve the making of
alterations to the Premises, Tenant shall comply with the provisions of Article
10.

                  Section 9.04. Subject to the other provisions of this Lease
imposing obligations regarding repair upon Tenant, Landlord shall repair all
machinery and equipment necessary to provide the services of Landlord described
in Article 7 (provided that Tenant shall pay the Actual Costs of any repair to
such systems or any part thereof damaged by Tenant and Tenant's employees,
customers, clients, agents, licensees and invitees, but only to the extent the
cost thereof is not covered and collected under Landlord's insurance or, if
Landlord is not carrying all of the insurance described in Section 14.02, to the
extent that such costs would not be covered by the insurance described in
Section 14.02 if the same were in effect), and for repair of all portions of the
project which do not comprise a part of the Premises and are not leased to
others.

                  Section 9.05. A. Tenant shall give Landlord written notice of
any default by Landlord in the observance or performance of any repair and/or
maintenance obligation required to be performed by Landlord under this Lease. If
any mortgagee of the Building has given Tenant its address for notice and
specifically requests to receive such written notice, Tenant agrees to give a
copy of the written notice required herein to such mortgagee at the same time
Tenant gives




                                     - 28 -
<PAGE>   35

the same to Landlord and to accept curative action. if any. undertaken by such
mortgagee as if such curative account had been taken by Landlord.

                                            B.  If Landlord defaults in the
observance or performance of any repair and/or maintenance obligation required
to be performed by it under this Lease, and any such default shall continue for
more than thirty (30) days after written notice thereof from Tenant or if such
failure cannot be corrected within such thirty (30) day period and Landlord does
not commence to correct the default and thereafter diligently prosecute the
correction of same to completion, Tenant may, except to the extent such default
is related to the Building Structure or Building Systems of the Building, but
shall not be obligated to, remedy such default and in connection therewith may
pay reasonable expenses. Notwithstanding the foregoing sentence or anything else
to the contrary in this Lease (i) in the event the Landlord's failure to
commence, or complete, a repair and/or maintenance obligation related to the
Building Structure or Building Systems has rendered the premises, or a portion
thereof, unusable, and Tenant is not using the Premises, or portion thereof, for
a period in excess of five (5) days after written notice to Landlord, Tenant
may, at Tenant's option, elect to remedy such failure or repair the Building
Structure or Building Systems so as to render the Premises usable, and (ii) in
the event of an emergency situation threatening immediate damage to property,
interruption to business, or injury to persons, Tenant shall use reasonable
efforts to provide Landlord oral notice, and if Landlord has not commenced the
repair and/or maintenance obligation within four (4) Business Hours thereafter,
Tenant may commence such repair and/or maintenance obligation. After such
emergency repairs, Tenant shall confirm such repairs by written notice. In the
event that (a) Landlord acknowledges that a default by Landlord in the
observance or performance of any term or covenant required to be performed under
this Lease, (b) Landlord does not dispute Tenant's claim of an alleged default
by Landlord, or (c) Landlord fails to reasonably and in good faith dispute such
Landlord default within thirty (30) days following delivery of written notice
from Tenant, then, in any such event, all reasonable and actual Tenant and/or
third party sums expended and reasonably incurred by Tenant in connection with
the cure of Landlord's default shall be due and owing within thirty (30) days
following written demand thereof to Landlord (the "Due Date"), accompanied by
invoices or other supporting documentation and evidence of such costs
substantiating such claim. In the event such sums are not paid within such time
period, Tenant shall have the right to offset its reasonable and actual Tenant
and/or third party expenses against Base Rent and Additional Rent, then, or
thereafter, due and owing, until Tenant has been fully reimbursed for such
costs.

                                            C.  Notwithstanding the foregoing
provision. Landlord may reasonably and in good faith dispute the Tenant's
declaration of a Landlord repair and/or maintenance default, including disputing
liability for payment of Tenant's costs of curing a purported Landlord repair
and/or maintenance default, and submit such matter to arbitration in accordance
with




                                     - 29 -
<PAGE>   36

Rider No. 5 ("General Arbitration") hereof. In the event that Landlord has
been determined through arbitration to be in default of a repair and/or
maintenance obligation, the sums demanded by Tenant shall bear interest from the
Due Date at the Interest Rate set forth in Section 4.02 hereof until paid in
full or offset. In the event that Landlord does not pay Tenant for its
reasonable and actual Tenant and/or third party expenses, plus interest at the
Interest Rate, incurred in effecting a cure of Landlord's default of a repair
and/or maintenance obligation within thirty (30) days of the determination in
arbitration. Tenant shall have the right to offset its reasonable and actual
Tenant and/or third party expenses, plus interest at the Interest Rate against
Base Rent and Additional Rent, then, or thereafter, due and owing, until Tenant
has been fully reimbursed for such costs. Landlord's right to dispute as set
forth above shall in no way be construed to limit or delay Tenant's right to
self-help as stated in this Section 9.05.

                                            D.  The payment of any Rent due
hereunder by Tenant shall in no manner constitute a waiver or release of any
claim which Tenant may have or be able to assert against Landlord, hereunder.
Notwithstanding anything to the contrary in this Section 9.05, Tenant shall be
not entitled to exercise its rights hereunder (except for the right of Tenant to
make repairs in the event of an emergency situation as more particularly set
forth in Section 9.05B above) until Tenant has provided Landlord's mortgagees of
whom Landlord has provided Tenant identities and addresses, written notice of
Landlord default of a repair and/or maintenance obligation.

                                   ARTICLE 10

                                   ALTERATIONS

                  Section 10.01. Tenant shall not at any time during the Term
make any alterations, additions or improvements to (collectively "Alterations")
to the Premises without first obtaining Landlord's written consent thereto,
which consent Landlord shall not unreasonably withhold or delay; provided,
however, that Landlord shall not withhold its consent unless such Alterations
(a) are visible from the exterior of the Building or the Project, (b) adversely
affect the Building Structure or Building Systems, (c) do not comply with
Applicable Laws, (d) unreasonably interfere with the normal and customary
business operations of the other tenants in the Building, or (e) are prohibited
by any underlying ground lease or mortgage (collectively "Design Problem").
Should Tenant desire to make any Alterations to the Premises, Tenant shall
submit all plans and specifications for such proposed Alterations to Landlord
for Landlord's review before Tenant allows any such work to commence and
Landlord shall within ten (10) days of receipt by Landlord of Tenant's plan and
specifications, unless additional review time is reasonably required, approve or
disapprove such plans and specifications for




                                     - 30 -
<PAGE>   37
any of the reasons set forth in this Section 10.01 or for any other reason
reasonably deemed sufficient by Landlord. Tenant shall select and use only
contractors, subcontractors or other repair personnel from those listed on
Landlord's approved list maintained by Landlord in the management office, or
contractors, subcontractors, or repair personnel reasonably approved by
Landlord. Upon Tenant's receipt of written approval from Landlord and any
required approval of any mortgagee or lessor of Landlord, and upon Tenant's
payment to Landlord of (a) any third party actual costs incurred by Landlord in
reviewing and approving such plans and specifications and (b) the fees, if any,
charged by any mortgagee or lessor of Landlord for such review and approval
Tenant shall have the right to proceed with the construction of all approved
Alterations, but only so long as such Alterations are in strict compliance with
the plans and specifications so approved by Landlord and with the provisions of
this Article 10. All Alterations shall he made at Tenant's sole cost and
expense, either by Tenant's contractors or, at Tenant's option, by Landlord on
terms reasonably satisfactory to Tenant, including a fee of eight percent (8%)
of the actual costs of such work to cover a fee for Landlord's agent or manager
in supervising and coordinating such work. In no event, however, shall anyone
other than Landlord or Landlord's employees or representatives perform work to
be done which affects the Building Structure or Building Systems. Landlord may,
as a condition to the installation thereof and if such request is made
concurrently with the approval of the plans and specifications therefor,
reasonably require Tenant to remove any such alterations, additions or
improvements at its sole cost and expense upon expiration or earlier termination
of the Term. Notwithstanding anything to the contrary set forth herein, Tenant
shall not be required to obtain Landlord's prior consent with respect to any
strictly cosmetic work performed within the Premises by Tenant, such as the
installation of wall coverings or floor coverings.

                  Section 10.02. All construction, Alterations and repair work
done by or for Tenant shall (a) be performed in such a manner as to maintain
harmonious labor relations; (b) not adversely affect the safety of the Project,
the Building or the Premises or the systems thereof and not adversely affect the
Building Structure or Building Systems; (c) comply with all building, safety,
fire, plumbing, electrical, and other codes and governmental and insurance
requirements; (d) not result in any usage in excess of Building Standard of
water, electricity, gas or other utilities or of heating ventilating or
air-conditioning (either during or after such work) unless prior written
arrangements satisfactory to Landlord are made with respect thereto; (e) be
completed promptly and in a good and workmanlike manner and in compliance with,
and subject to all of the provisions of Article 2 of Exhibit C hereof; and (f)
not unreasonably disturb Landlord or other tenants in the Building. After
completion of any Alterations to the Premises, Tenant will deliver to Landlord a
copy of "as built" plans and specifications depicting and describing such
alterations.




                                     - 31 -
<PAGE>   38

                  Section 10.03. All Leasehold Improvements, Alterations and
other physical additions made to or installed by or for Tenant in the Premises
shall be and remain Landlord's property (except for Tenant's furniture, personal
property and movable trade fixtures) and shall not be removed without Landlord's
written consent. Tenant agrees to remove, at its sole cost and expense, all of
Tenant's furniture, personal property and movable trade fixtures, and, if
directed to do so by Landlord in writing at the time Tenant requests Landlord's
consent to such Alterations or Leasehold Improvements for which Landlord's prior
reasonable consent is required all, or any part of the Leasehold Improvements.
Alterations and other physical additions made by Tenant to the Premises. which
Landlord, as a reasonable condition to the approval of same has required Tenant
to remove, on or before the Expiration Date or any earlier date of termination
of this Lease. Tenant shall repair or promptly reimburse Landlord for the cost
of repairing, all damage done to the Premises or the Building by such removal.
Any Leasehold Improvements, Alterations or physical additions made by Tenant
which Landlord does not direct or permit Tenant to remove at any time during or
at the end of the Term shall become the property of Landlord at the end of the
Term without any payment to Tenant. If Tenant fails to remove any of Tenant's
furniture, personal property or movable trade fixtures by the Expiration Date or
any sooner date of termination of the Lease or, if Tenant fails to remove any
Leasehold Improvements, Alterations and other physical additions made by Tenant
to the premises which Landlord has in writing directed Tenant to remove,
Landlord shall have the right, on the fifth (5th) day after Landlord's delivery
of written notice to Tenant to deem such property abandoned by Tenant and to
remove, store, sell, discard or otherwise deal with or dispose of such abandoned
property in a commercially reasonable manner. Tenant shall be liable for all
costs of such disposition of Tenant's abandoned property and Landlord shall have
no liability to Tenant in any respect regarding such property of Tenant. The
provisions of this Section 10.03 shall survive the expiration or any earlier
termination of this Lease.

                                   ARTICLE 11

                                      LIENS

                  Section 11.01. Tenant shall keep the Project, the Building and
the Premises and Landlord's interest therein, free from any liens arising from
any work performed, materials furnished. or obligations incurred by or on behalf
of Tenant (other than by Landlord pursuant to Exhibit C). Notice is hereby given
that neither Landlord nor any mortgagee or lessor of Landlord shall be liable
for any labor or materials furnished to Tenant except as furnished to Tenant by
Landlord pursuant to Exhibit C. If any lien is filed for such work or materials
such lien shall encumber only Tenant's interest in Leasehold Improvements on the
Premises. Within ten (10) days after Tenant learns of the filing of any such
lien, Tenant shall notify Landlord of such lien and shall either discharge and
cancel such lien of record or post a bond



                                     - 32 -
<PAGE>   39

sufficient under the laws of the State of Texas to cover the amount of the lien
claim plus any penalties, interest, attorneys' fees, court costs, and other
legal expenses in connection with such lien. If Tenant fails to so discharge or
bond such lien within thirty (30) calendar days after written demand from
Landlord, Landlord shall have the right at Landlord's option, to pay the full
amount of such lien without inquiry into the validity thereof, and Landlord
shall be promptly reimbursed by Tenant, as Additional Rent, for all amounts so
paid by Landlord, including expenses, interest, and attorneys' fees.

                                   ARTICLE 12

                          USE AND COMPLIANCE WITH LAWS

                  Section 12.01. The Premises shall be used only for the uses
specifically set forth in Section 1.01Q and for no other purposes whatsoever.
Tenant shall use and maintain the Premises in a clean, careful, safe and lawful
manner and shall not cause or knowingly permit within the Premises, any
offensive noise, order, conduct or private or public nuisance or cause or
knowingly permit Tenant's employees, agents, licensees or invitees to create a
public or private nuisance or act in a disorderly manner within the Building or
in the Project. Any statement as to the particular nature of the business to be
conducted by Tenant in the Premises and uses to be made thereof by Tenant as set
forth in Section 1.01Q hereof shall constitute a representation or warranty by
Landlord that such business or uses are lawful and permissible under any
certificate or occupancy for the Premises or the Building and are otherwise
permitted by law. Landlord also represents that any certificate of occupancy
issued with respect to the Premises shall allow use for executive and
administrative offices.

                  Section 12.02. Tenant shall, at Tenant's sole expense (a)
comply with all laws, orders, ordinances, and regulations of federal, state,
county, and municipal authorities having jurisdiction over the Premises, (b)
comply with any directive, order or citation made pursuant to law by any public
officer requiring abatement of any nuisance or which imposes upon Landlord or
Tenant any duty or obligation arising from Tenant's occupancy or use of the
Premises or from conditions which have been created by or at the request or
insistence of Tenant, or required by reason of a breach of any of Tenant's
obligations hereunder or by or through other fault of Tenant, (c) comply with
all insurance requirements applicable to the Premises and (d) except as may be
due to the negligence or willful misconduct of Landlord or Landlord's agents,
contractors, employees or licensees, indemnify and hold Landlord harmless from
any loss, cost, claim or expense which Landlord incurs or suffers by reason of
Tenant's failure to comply with its obligations under clauses (a), (b) or (c)
above. If Tenant receives notice of any such directive, order citation or of any
violation of any law, order, ordinance, regulation or any insurance requirement,
Tenant shall promptly notify Landlord in writing of such alleged



                                     - 33 -
<PAGE>   40

violation and furnish Landlord with a copy of such notice. Notwithstanding the
foregoing, costs of any such compliance which is necessitated by Tenant's
particular use and occupancy of the Premises shall be paid by Tenant; all other
costs of any such compliance shall be paid by Landlord and, to the extent
expressly provided for in this Lease, included in Operating Costs, and Tenant
shall, except to the extent expressly provided otherwise in this Lease, bear and
pay Tenant's Share thereof as provided in Article 5. Notwithstanding the
foregoing, costs of any such compliance which is necessitated by Tenant's
particular use and occupancy of the Premises shall be paid by Tenant, all other
costs of any such compliance shall be paid by Landlord and, to the extent
expressly provided for in this Lease, bear and pay Tenant's Share thereof as
modified in Article 5. Landlord shall use commercially reasonable efforts at
least comparable to those that would be used by other landlords of Comparable
Buildings, to secure the compliance by third parties with all use restrictions
affecting the Building; provided however, that Landlord shall not, so long as
Landlord is using commercially reasonable efforts; be liable to Tenant for any
third parties' failure to conduct itself in accordance with the provisions of
this Article 12, and Tenant shall not be released or excused from the
performance of any of its obligations under the lease solely because of such
failure.

                                   ARTICLE 13

                              DEFAULT AND REMEDIES

                  Section 13.01. The occurrence of any one or more of the
following events shall constitute an Event of Default (herein so called) of
Tenant under this Lease: (a) if Tenant fails to pay any Rent hereunder as and
when such Rent becomes due and such failure shall continue for more than seven
(7) days after Landlord gives Tenant notice of past due Rent; (b) if Tenant
fails to pay Rent on time more than four (4) times after delivery of notice in
any period of twelve (12) months, notwithstanding that such payments have been
made within the applicable cure period; (c) if Tenant permits to be done
anything which creates a lien upon the Premises and fails to discharge or bond
such lien or post such security with Landlord as is required by Article 11; (d)
if Tenant fails to maintain in force all policies of insurance required by this
Lease and such failure shall continue for more than thirty (30) days after
Landlord gives Tenant notice of such failure; (e) if any petition is filed by or
against Tenant or any guarantor of this Lease under any present or future
section or chapter of the Bankruptcy Code, or under any similar law or statute
of the United States or any state thereof (which, in the case of an involuntary
proceeding, is not permanently discharged, dismissed, stayed, or vacated, as the
case may be, within sixty (60) days of commencement), or if any order for relief
shall be entered against Tenant or any guarantor of this Lease in any such
proceedings; (f) if Tenant or any guarantor of this Lease becomes insolvent or
makes a transfer in fraud of creditors or makes an assignment for the benefit of
creditors; (g) if a receiver, custodian, or trustee is appointed for the
Premises or for



                                     - 34 -
<PAGE>   41

all or substantially all of the assets of Tenant or of any guarantor of this
Lease, which appointment is not vacated within sixty (60) days following the
date of such appointment; (h) if Tenant fails to perform or observe any other
terms of this Lease and such failure shall continue for more than thirty (30)
days after Landlord gives Tenant notice of such failure, or, if such failure
cannot be corrected within such thirty (30) day period. If Tenant does not
commence to correct such default within such thirty (30) day period and
thereafter diligently prosecute the correction of same to completion within a
reasonable time.

                  Section 13.02. Upon the occurrence of any Event of Default,
Landlord shall have the right, at Landlord's option, to elect to do any one or
more of the following without further notice or demand to Tenant: (a) terminate
this Lease, in which event Tenant shall immediately surrender the Premises to
Landlord, and, if Tenant fails to so surrender, Landlord shall have the right,
without notice, to enter upon and take possession of the Premises and to expel
or remove Tenant and its effects without being liable for prosecution or any
claim for damages therefor; and Tenant shall, and hereby agrees to, indemnify
Landlord for all loss and damage which Landlord suffers by reason of such
termination, including damages in an amount equal to the total of (1) the costs
of recovering the Premises and all other expenses incurred by Landlord in
connection with Tenant's default; (2) the unpaid Rent earned as of the date of
termination, plus interest at the Interest Rate; (3) the total Rent which
Landlord would have received under this Lease for the remainder of the Term, but
discounted to the then present value at a rate of eight percent (8%) per annum,
over the fair market rental value on a net basis of the balance of the Term as
of the time of such default, discounted to the then present value at a rate of
eight percent (8%) per annum; and (4) all other sums of money and damages owing
by Tenant to Landlord; or (b) enter upon and take possession of the Premises
without terminating this Lease and without being liable to prosecution or any
claim for damages therefor, and, if Landlord elects, relet the Premises on such
terms as Landlord deems advisable, in which event Tenant shall pay to Landlord
on demand the cost of repossession, renovating, repairing and altering the
Premises for a new tenant or tenants and any deficiency between the Rent payable
hereunder and the rent paid under such reletting; provided, however, that Tenant
shall not be entitled to any excess payments received by Landlord from such
reletting. Landlord's failure to relet the Premises shall not release or affect
Tenant's liability for Rent or for damages; or (c) enter the Premises without
terminating this Lease and without being liable for prosecution or any claim for
damages therefor and maintain the Premises and repair or replace any damage
thereto or do anything for which Tenant is responsible hereunder. Tenant shall
reimburse Landlord immediately upon demand for any expenses which Landlord
incurs in thus effecting Tenant's compliance under this Lease, and Landlord
shall not be liable to Tenant for any damages with respect thereto.
Notwithstanding the foregoing, in no event shall Tenant be responsible to
Landlord for consequential damages.


                                     - 35 -
<PAGE>   42

                  Section 13.03. No agreement to accept a surrender of the
Premises and no act or omission by Landlord or Landlord's agents during the Term
shall constitute an acceptance or surrender of the Premises unless made in
writing and signed by Landlord. No re-entry or taking possession of the Premises
by Landlord shall constitute an election by Landlord to terminate this Lease
unless a written notice of such intention is given to Tenant. No provision of
this Lease shall be construed as an obligation upon Landlord to mitigate
Landlord's damages under the Lease.

                  Section 13.04. No provision of this Lease shall be deemed to
have been waived by Landlord or Tenant, as the case may be, unless such waiver
is in writing and signed by the waiving party. Landlord's acceptance of Rent
following an Event of Default hereunder shall not be construed as a waiver of
such Event of Default. No custom or practice which may grow up between the
parties in connection with the terms of this Lease shall be construed to waive
or lessen either Tenant's or Landlord's right to insist upon strict performance
of the terms of this Lease, without a written notice thereof from the waiving
party to the other party.

                  Section 13.05. The rights granted to Landlord and Tenant in
this Article 13 shall be cumulative of every other right or remedy provided in
this Lease or which Landlord and Tenant may otherwise have at law or in equity
or by statute, and the exercise of one or more rights or remedies shall not
prejudice or impair the concurrent or subsequent exercise of other rights or
remedies or constitute a forfeiture or waiver of Rent or damages accruing to
Landlord or Tenant by reason of any Event of Default or default under this
Lease. Each party ("Payor") agrees to pay to the other party ("Payee") all costs
and expenses incurred by the Payee in the enforcement of this Lease, including
all attorneys' fees incurred in connection with the collection of any sums due
hereunder or the enforcement of any right or remedy of Landlord.

                  Section 13.06. Landlord shall be in default in the performance
of any obligation required to be performed by Landlord under this Lease if
Landlord has failed to perform such obligation within thirty (30) days after the
receipt of notice from Tenant specifying in detail Landlord's failure to
perform; provided, however, that if the nature of Landlord's obligation is such
that more than thirty (30) days are required for its performance, Landlord shall
not be deemed in default if it shall commence such performance within thirty
(30) days and thereafter diligently pursues the same to completion.

                                   ARTICLE 14

                                    INSURANCE

                  Section 14.01. A. Tenant, at its sole expense, shall obtain
and keep in force during the Term the following insurance: (a) "All Risk"
insurance



                                     - 36 -
<PAGE>   43

insuring the Leasehold Improvements, Tenant's interest in the Premises and all
property located in the Premises, including furniture, equipment, fittings,
installations, fixtures, supplies and any other personal property, leasehold
improvements and alterations ("Tenant's Property"), in an amount equal to the
full replacement value, it being understood that no lack or inadequacy of
insurance by Tenant shall in any event make Landlord subject to any claim by
virtue of any theft of or loss or damage to any uninsured or inadequately
insured property; (b) Business Interruption insurance in an amount that will
reimburse Tenant for direct loss of earnings attributable to all perils insured
against under Section 14.01(a) or attributable to the prevention of access to
the Premises by civil authority; and sufficient to reimburse Tenant for Rent in
the event of a casualty to, or temporary taking of, the Building or the
Premises; (c) Commercial general liability insurance including personal injury,
bodily injury, broad form property damage, operations hazard, owner's protective
coverage, contractual liability, with a cross liability clause and a
severability of interests clause to cover Tenant's indemnities set forth herein,
and products and completed operations liability, in limits not less than
$1,000,000.00 inclusive per occurrence; (d) Worker's Compensation and Employer's
Liability insurance, in form and amount as required by applicable law; and (e)
In the event Tenant performs any repairs or alterations in the Premises,
Builder's Risk insurance on an "All Risk" basis (including collapse) on a
completed value (non-reporting) form for full replacement value covering all
work incorporated in the Building and all materials and equipment in or about
the Premises; (f) tenant's "All Risk" Legal Liability insurance for the
replacement cost value of the Premises; and (g) any other form or forms of
insurance or any changes or endorsements to the insurance required herein as any
mortgagee or lessor of Landlord may reasonably require, from time to time, in
form or in amount, provided comparable landlords in Comparable Buildings are
requiring such insurance.

                  B. Tenant shall have the right to include the insurance
required by Section 14.01A under Tenant's policies of "blanket insurance,"
provided that no other loss which may also be insured by such blanket insurance
shall affect the insurance coverages required hereby and further provided that
Tenant delivers to Landlord a certificate specifically stating that such
coverages apply to Landlord, the Premises and the Project. All such policies of
insurance or certificates thereof shall name Tenant as named insured thereunder
and shall name Landlord and all mortgagees and lessors of Landlord, of which
Tenant has been notified, additional insureds, all as their respective interest
may appear. All such certificates shall be issued by insurers acceptable to
Landlord and in form satisfactory to Landlord. Tenant shall deliver to Landlord
certificates by the Commencement Date and, with respect to renewals of such
policies, not later than thirty (30) days prior to the end of the expiring term
of coverage. All policies of insurance shall be primary and Tenant shall not
carry any separate or additional insurance concurrent in form or contributing in
the event of any loss or damage with any insurance required to be maintained by
Tenant under this Lease. All such policies and certificates shall contain an
agreement by the insurers that the policies will not be invalidated as



                                     - 37 -
<PAGE>   44

they affect the interests of Landlord and Landlord's mortgagees by reason of any
breach or violation of warranties, representations, declaration or conditions
contained in the policies and that the insurers shall notify Landlord and any
mortgagee or lessor or Landlord in writing, by U.S. mail, not less than
forty-five (45) days before any material change, reduction in coverage,
cancellation, including cancellation for nonpayment of premium, or other
termination thereof or change therein.

                  Section 14.02. Landlord shall insure the Building against
damage with (a) property insurance for All Risks, including flood and ordinance
or law coverage endorsement and demolition costs and increased cost of
construction endorsement, and (b) and commercial general liability insurance, at
minimum limits of $2,000,000.00 general aggregate, $1,000,000.00 each
occurrence, and $1,000,000.00 personal and advertising injury, with such
deductibles as Landlord reasonably deems appropriate, but in all events at least
equal to insurance maintained by comparable landlords in Comparable Buildings.
Notwithstanding any contribution by Tenant to the cost of insurance premiums, as
provided hereinabove, Landlord shall not be required to carry insurance of any
kind on Tenant's Property, and Tenant hereby agrees that Tenant shall have no
right to receive any proceeds from any insurance policies carried by Landlord.

                  Section 14 03. Tenant shall not knowingly conduct or permit to
be conducted in the Premises any activity, or place any equipment in or about
the Premises or the Building, which will invalidate the insurance coverage in
effect or increase the rate of fire insurance or other insurance on the Premises
or the Building, and Tenant shall comply with all requirements and regulations
of Landlord's casualty and liability insurer. If any invalidation of coverage or
increase in the rate of fire insurance or other insurance occurs or is
threatened by any insurance company due to any act or omission by Tenant, or its
agents, employees, representatives, or contractors, such statement or threat
shall be conclusive evidence that the increase in such rate is due to such act
of Tenant or the contents or equipment in or about the Premises, and, as a
result thereof, Tenant shall be liable for such increase and shall be considered
Additional Rent payable with the next monthly installment of Base Rent due under
this Lease. In no event shall Tenant introduce or permit to be kept on the
Premises or brought into the Building any dangerous, noxious, radioactive or
explosive substance.

                  Section 14.04. Landlord and Tenant each hereby waive any right
of subrogation and right of recovery or cause of action for injury or loss to
the extent that such injury or loss is covered by fire, extended coverage, "All
Risk" or similar policies covering real property or personal property (or which
would have been covered if Tenant or Landlord, as the case may be, was carrying
the insurance required by this Lease). Said waivers shall be in addition to, and
not in limitation or derogation or, any other waiver or release contained in
this Lease. Written notice of the terms of the above mutual waivers shall be
given to the insurance



                                     - 38 -
<PAGE>   45
carriers of Landlord and Tenant and the parties' insurance policies shall be
properly endorsed, if necessary, to prevent the invalidation of said policies by
reason of such waivers.

                                   ARTICLE 15

                          DAMAGE BY FIRE OR OTHER CAUSE

                  Section 15.01. If the Building, or any portion thereof, which
does not affect Tenant's Premises as set forth in Section 15.02 hereinbelow, is
damaged or destroyed by any casualty to the extent that, in the reasonable
judgment of Landlord (a) repair of such damage or destruction would not be
economically feasible, or (b) the damage or destruction to the Building cannot
be repaired within three hundred sixty (360) days after the date of such damage
or destruction, or (c) the proceeds from insurance remaining after any required
payment to any mortgagee or lessor of Landlord are insufficient to repair such
damage or destruction, Landlord shall have the right, at Landlord's option, to
terminate this Lease by giving Tenant written notice of such termination, within
thirty (30) days after the date of such damage or destruction.

                  Section 15.02. If the Premises, or any portion thereof, is
damaged or destroyed by any casualty, or casualty to the Building, or any
portion thereof, renders the Premises totally and partially inaccessible or
unusable by Tenant for the ordinary conduct of Tenant's business, in the
reasonable judgment of Landlord, (a) the Premises cannot be rebuilt or made fit
for Tenant's purposes, or the Building repaired so as to render the Premises
accessible and usable by Tenant for the ordinary conduct of Tenant's business,
within ninety (90) days after the date of such damage or destruction, or (b) if
the proceeds from the insurance Tenant is required to maintain pursuant to
Article 14 hereof (or the amount of proceeds which would have been available if
Tenant was carrying such insurance) are insufficient to repair such damage or
destruction, then Tenant shall have the right to terminate this Lease by giving
Landlord written notice, within thirty (30) days after Landlord advises Tenant,
in writing, of the period of time required to make such repairs, which Landlord
notice shall be given to Tenant within thirty (30) days of such damage or
destruction.

                  Section 15.03. In the event of partial destruction or damage
to the Building or the Premises which is not subject to Section 15.01 or 15.02,
but which renders the Premises partially but not wholly unusable, this Lease
shall not terminate and Rent shall be abated in proportion to the area of the
Premises which, in Tenant's reasonable opinion, cannot be used or occupied by
Tenant as a result of such casualty. Landlord shall in such event, within a
reasonable time after the date of such destruction or damage, subject to force
majeure (as defined in Section 25.06) or to delays caused by Tenant and to the
extent and availability of insurance



                                     - 39 -
<PAGE>   46

proceeds, restore the Premises to as near the same condition as existed prior to
such partial damage or destruction.

                  Section 15.04. If the Building or the Premises or any portion
thereof is destroyed by fire or other causes at any time during the last year of
the Term, or, if an applicable renewal option has been exercised, during the
last year of any renewal term, so that Tenant shall be prevented from using the
Premises for thirty (30) consecutive days due to such damage or destruction,
then either Landlord or Tenant shall have the right. at the option of either
party, to terminate this Lease by giving written notice to the other within
thirty (30) days after the date of such destruction.

                  Section 15.05. Landlord shall have no liability to Tenant for
inconvenience, loss of business, or annoyance arising from any repair of any
portion of the Premises or the Building. If Landlord is required by this Lease
or by my mortgagee or lessor of Landlord to repair. Tenant shall pay to Landlord
that amount of Tenant's insurance proceeds, if any. (or the amount which would
have been received by Tenant if Tenant was carrying the insurance required by
this Lease) which insures such damage as a contribution towards such repair, and
Landlord shall use reasonable efforts to have such repairs made promptly and in
a manner which will not unnecessarily interfere with Tenant's occupancy.

                  Section 15.06. In the event of termination of this Lease
pursuant to Sections 15.01, 15.02. or 15.04, then all Rent shall be apportioned
and paid to the date on which possession is relinquished or the date of such
damage, whichever last occurs. and Tenant shall immediately vacate the Premises
according to such notice of termination, provided, however, that those
provisions of this Lease which are designated to cover matters of termination
and the period thereafter shall survive the termination hereof.

                                   ARTICLE 16

                                  CONDEMNATION

                  Section 16.01. In the event the whole or substantially the
whole of the Building or the Premises, or any portion of the Premises as to
render the balance unusable for Tenant's business purposes. are taken or
condemned by eminent domain or by any conveyance in lieu thereof (such taking,
condemnation or conveyance in lieu thereof being hereinafter referred to as
"condemnation"), the Term shall cease and this Lease shall terminate on the
earlier of the date the condemning authority takes possession or the date title
vests in the condemning authority.

                  Section 16.02. In the event any portion of the Building shall
be taken by condemnation (whether or not such taking includes any portion of the


                                     - 40 -
<PAGE>   47

Premises), which taking, in Landlord's judgment, is such that the Building
cannot be restored in an economically feasible manner for use substantially as
originally designed, then Landlord shall have the right, at Landlord's option,
to terminate this Lease, effective as of the date specified by Landlord in a
written notice of termination from Landlord to Tenant.

                  Section 16.03. In the event any portion of the Parking
Facilities shall be taken by condemnation, which taking in Landlord's judgment
is such that the Parking Facilities cannot be restored in an economically
feasible manner for use substantially as originally designed, including in such
consideration the possible use of additional parking facilities in the vicinity
of the Building, then Landlord shall have the right, at Landlord's option, to
terminate this Lease, effective as of the date specified by Landlord in a
written notice of termination from Landlord to Tenant.

                  Section 16.04. In the event that a portion, but less than
substantially the whole, of the Premises shall be taken by condemnation, then
this Lease shall be terminated as of the date of such condemnation as to the
portion of the Premises so taken, and unless Landlord exercises its option to
terminate this Lease pursuant to Section 16.02, this Lease shall remain in full
force and effect as to the remainder of the Premises and Landlord shall restore
the Premises to the extent of available condemnation proceeds.

                  Section 16.05. In the event of termination of this Lease, as
to the whole or any portion of the Premises, pursuant to the provisions of
Section 16.01, 16.02, 16.03, or 16.04, the Rent shall be proportionally reduced
as of such date of termination: provided, however, that those provisions of this
Lease which are designated to cover matters of termination and the period
thereafter shall survive the termination hereof. Upon termination of the Lease
pursuant to this Article 16, Tenant and Landlord hereby agree to release each
other from any and all obligations and liabilities with respect to the Lease
except such obligations and liabilities which arise or accrue prior to such
termination. Notwithstanding the foregoing, Landlord and Tenant shall equally
share nay recovery from the condemning authority of the so-called "Bonus Value"
of the leasehold estate which shall be equal to the difference between the
rental rate payable under the Lease and the rate established by the condemning
authority as an award for compensation purposes.

                  Section 16.06. All compensation awarded or paid upon a
condemnation of any portion of the Project shall belong to and be the property
of Landlord without participation by Tenant. Nothing herein shall be construed,
however, to give Landlord any interest in, require Tenant to assign to Landlord,
or preclude Tenant from prosecuting any claim directly against the condemning
authority for loss of business, loss of goodwill, moving expenses, damage to,
and cost of removed of, trade fixtures, furniture and other personal property
belonging



                                     - 41 -
<PAGE>   48

to Tenant; provided, however, that Tenant shall make no claim which shall
diminish or adversely affect any award claimed or received by Landlord.

                  Section 16.07. If any portion of the Project other than the
Building is taken by condemnation or if the temporary use or occupancy of all or
any part of the Premises shall be taken by condemnation during the Term, this
Lease shall be and remain unaffected by such condemnation, and Tenant shall
continue to pay in full the Rent payable hereunder. In the event of any such
temporary taking for use or occupancy of all or any part of the Premises, Tenant
shall be entitled to appear, claim, prove and receive the portion of the award
for such taking that represents compensation for use or occupancy of the
Premises during the Term and Landlord shall be entitled to appear, claim, prove
and receive the portion of the award that represents the cost of restoration of
the Premises and the use or occupancy of the Premises after the end of the Term
hereof. In the event of any such condemnation of any portion of the Project
other than the Building, Landlord shall be entitled to appear, claim, prove and
receive all of that award.

                                   ARTICLE 17

                                 INDEMNIFICATION

                  Section 17.01. Tenant hereby waives all claims against
Landlord for damage to any property or injury to, or death of, any person in,
upon, or about the Project, including the Premises, arising at any time and from
any cause other than by reason of the acts, omissions, negligence or willful
misconduct of Landlord, its agents, employees, representatives, or contractors.
Tenant shall, and hereby agrees to, indemnify and hold Landlord harmless from
any damage to any property or injury to, or death of, any person arising from
the use or occupancy of the Common Areas and the Premises by Tenant, its agents,
employees, representatives, contractors, successors, assigns, licensees, or
invitees, unless such damage is caused by the acts, omissions, negligence or
willful misconduct of Landlord, its agents, employees, representatives, or
contractors. Landlord shall not be liable for any such damage caused by other
tenants or persons in the Building or by occupants of adjacent property thereto,
or by the public, or caused by construction (unless caused by the gross
negligence or willful misconduct of Landlord) or by any private, public or
quasi-public work. Tenant's foregoing indemnity shall include attorneys' fees,
investigation costs, and all other reasonable costs and expenses incurred by
Landlord in any connection therewith. The provisions of this Article 17 shall
survive the expiration or termination of this Lease with respect to any damage,
injury, or death occurring before such expiration or termination.

                  Section 17.02. Landlord hereby waives all claims against
Tenant for damage to any property or injury to, or death of, any person in,
upon, or about the Project, including the Premises, arising at any time and
from any cause other



                                     - 42 -
<PAGE>   49

than by reason of the acts, omission, negligence or willful misconduct of
Tenant, its agents, employees, representatives, or contractors. Landlord shall,
and hereby agrees to, indemnify and hold Tenant harmless from any damage to any
property or injury to, or death of, any person arising from the use or occupancy
of the Common Areas and the Premises by Landlord, its agents, employees,
representatives, contractors, successors, assigns, licensees, or invitees,
unless such damage is caused by the acts, omissions, negligence or willful
misconduct of Tenant, its agents, employees, representatives, or contractors.
Tenant shall not be liable for any such damage caused by Landlord, its agents,
employees, representatives, or contractors, or persons in the Building or by
occupants of adjacent property thereto, or by the public, or caused by
construction (unless caused by the gross negligence or willful misconduct of
Tenant) or by any private, public or quasi-public work. Landlord's foregoing
indemnity shall include attorneys' fees, investigation costs, and all other
reasonable costs and expenses incurred by Tenant in any connection therewith.
The provisions of this Article 17 shall survive the expiration or termination of
this Lease with respect to any damage, injury, or death occurring before such
expiration or termination.

                  Section 17.03. Tenant's and Landlord's agreements to indemnify
and hold the other party harmless pursuant to Article 17 are not intended to and
shall not relieve any insurance carrier of its obligations under policies
required to be carried by Landlord or Tenant, respectively, pursuant to the
Lease to the extent that such policies cover the results of such acts,
omissions, negligence, or willful misconduct. If Landlord or Tenant has been or
at any time hereafter is granted the right to self insure or if either party
breaches this agreement by its failure to carry required insurance, such failure
shall automatically be deemed to be a covenant and agreement by Landlord or
Tenant, respectively, to self-insure to the full extent of such required
coverage, with full waiver of subrogation. All of the provisions set forth
herein are subject to the provisions of Section 17.04.

                  Section 17.04. Allocation of Insured Risks/Subrogation.
Landlord and Tenant release each other from any claims and demands of whatever
nature for damage, loss or injury to the Premises and/or the Building, or to the
other's property in, on or about the Premises and the Building, that are caused
by or result from risks or perils insured against under any property insurance
policies required by the Lease to be carried by Landlord and/or Tenant. Landlord
and Tenant shall cause each insurance policy obtained by them or either of them
to provide that the insurance company waives all right of recovery by way of
subrogation against either Landlord or Tenant in connection with any damage
covered by any such policy or policies. Neither Landlord nor Tenant shall be
liable to the other for any damage caused by fire or any of the risks insured
against under any insurance policy required by the Lease. If an insurance policy
cannot be obtained with a waiver of subrogation, or is obtainable only by the
payment of an additional premium charge above that charged by insurance
companies issuing policies without waiver of subrogation, the party undertaking
to obtain the insurance shall notify the other



                                     - 43 -
<PAGE>   50

party of this fact. The other party shall have a period of ten (10) days after
receiving the notice either to place the insurance with a company that is
reasonably satisfactory to the other party and that will carry the insurance
with a waiver of subrogation at no additional cost, or to agree to pay the
additional premium if such a policy is obtainable at additional cost. If the
insurance cannot be obtained or the party in whose favor a waiver of subrogation
is desired refuses to pay the additional premium charged, the other party is
relieved of the obligation to obtain a waiver of subrogation with respect to the
particular insurance involved.

                                   ARTICLE 18

                     SUBORDINATION AND ESTOPPEL CERTIFICATES

                  Section 18.01. This Lease and all rights of Tenant hereunder
are subject and subordinate to all underlying leases now in existence, and to
any supplements, amendments modifications, and extensions of such leases
heretofore or hereafter made and to any deeds to secure debt, mortgages, or
other security instruments which now cover all or any portion of the Project or
any interest of Landlord therein, and to any advances made on the security
thereof, and to any increases, renewals, modifications, consolidations,
replacements, and extensions of any of such mortgages. This provision is
declared by Landlord and Tenant to be self-operative and no further instrument
shall be required to effect such subordination of this Lease. Upon thirty (30)
days' notice, however, Tenant shall execute, acknowledge, and deliver to
Landlord any further instruments and certificates evidencing such subordination
as Landlord, and any mortgagee or lessor of Landlord shall reasonably require.
Tenant shall not unreasonably withhold, delay, or defer its written consent to
reasonable modifications in this Lease which are a condition of any
construction, interim or permanent financing for the Project or any reciprocal
easement agreement with facilities in the vicinity of the Building, provided
that such modifications do not increase the obligations of Tenant hereunder or
materially and adversely affect Tenant's use and employment of the Premises.
This Lease is further subject and subordinate to: (a) all applicable ordinances
of any government authority having jurisdiction over the Project, relating to
easements, franchises, and other interests or rights upon, across, or
appurtenant to the Project; and (b) all utility easements and agreements, now or
hereafter created for the benefit of the Project.

                  Section 18.02. Notwithstanding the generality of the foregoing
provisions of Section 18.01, any mortgagee or lessor of Landlord shall have the
right at any time to subordinate any such mortgage or underlying lease to this
Lease, or to any of the provisions hereof, on such terms and subject to such
conditions as such mortgagee or lessor of Landlord may consider appropriate in
its discretion. At any time, before or after the institution of any proceedings
for the foreclosure of any such mortgage, or the sale of the Building under any
such mortgage, or the



                                     - 44 -
<PAGE>   51
termination of any underlying lease, Tenant shall, upon request of such
mortgagee or any person or entities succeeding to the interest of such mortgagee
or the purchaser at any foreclosure sale ("Successor Landlord"), automatically
become the Tenant of the Successor Landlord, without change in the terms or
other provisions of this Lease; provided, however, that the Successor Landlord
shall not be (i) bound by any payment made by Tenant of Rent or Additional Rent
for more than one (1) month in advance, except for a Security Deposit previously
paid to Landlord, (ii) liable for any damages or subject to any offset or
defense by Tenant to the payment of Rent by reason of any act or omission of any
prior landlord (including Landlord), unless such Successor or Landlord has been
advised by Tenant, in writing, of such damage, offset right, defense, or claim
prior to Successor Landlord acquiring the Project; or, (iii) personally or
corporately liable, in any event, beyond the limitations on landlord liability
set forth in Section 25.05 of this Lease. This agreement of Tenant to attorn to
a Successor Landlord shall survive any such foreclosure sale, trustee's sale
conveyance in lieu thereof or termination of any underlying lease. Tenant shall
upon thirty (30) days' notice at any time, before or after any such foreclosure
or termination execute, acknowledge, and deliver to the Successor Landlord any
reasonable written instruments and certificates evidencing such attornment as
such Successor Landlord may reasonably require; provided, however, that Landlord
shall require that such agreement provide that upon such attornment as long as
Tenant is not in default hereunder, with any applicable cure period having
expired. Tenant's possession of the Premises under this Lease shall not be
disturbed.

                  Section 18.03. Tenant shall, from time to time, within fifteen
(15) days after request from Landlord, or from any mortgagee or lessor of
Landlord, execute, acknowledge and deliver in recordable form a certificate
certifying, to the extent true, that this Lease is in full force and effect and
unmodified (or, if there have been modifications, that the same is in full force
and effect as modified and stating the modifications); that the Term has
commenced and the full amount of the Rent then accruing hereunder; the dates to
which the Rent has been paid; that Tenant has accepted possession of the
Premises and that any improvements required by the terms of this Lease to be
made by Landlord have been completed to the satisfaction of Tenant (or if not
completed by Landlord, a list of the remaining items to be completed by
Landlord); the amount, if any, that Tenant has paid to Landlord as a Security
Deposit; that no Rent under this Lease has been paid more than thirty (30) days
in advance of its due date; that the address for notices to be sent to Tenant is
as set forth in this Lease (or has been changed by notice duly given and is as
set forth in the certificate); that Tenant, as of the date of such certificate,
has no charge, lien, or claim of offset under this Lease or otherwise against
Rent or other charges due or to become due hereunder (or if Tenant shall have a
charge, lien, or claim of offset under this Lease or against Rent, such items);
that, to the knowledge of Tenant, Landlord is not then in default under this
Lease; and such other matters as may be reasonably requested by Landlord or any
mortgagee or lessor of Landlord. Any such certificate may be relied upon by


                                     - 45 -
<PAGE>   52

Landlord, any Successor Landlord, or any mortgagee or lessor of Landlord.
Landlord agrees periodically to furnish, when reasonably requested in writing by
Tenant, certificates signed by Landlord containing information similar to the
foregoing information. Landlord hereby agrees to provide to Tenant an estoppel
certificate signed by Landlord, containing substantially the same types of
information and within the same periods of time as are set forth in Section
18.03, except such charges as are reasonably necessary to reflect that the
estoppel certificate is being granted and signed by Landlord to Tenant or
Tenant's lender, assignee or sublessee, rather than from Tenant to Landlord or
to a lender or purchaser.

                  Section 18.04. Landlord agrees that within thirty (30) days
after the date of full execution of the Lease, it will provide Tenant with
non-disturbance, subordination and attornment agreements ("non-disturbance
agreement") in favor of Tenant from any ground lessors, mortgage holders or lien
holders (each, a "Superior Mortgage") then in existence, if such recording is
permitted by such Superior Mortgage. Said non-disturbance agreements shall be in
recordable form and may be recorded, if such recording is permitted by such
Superior Mortgagee, at Tenant's election and expense. In the event Landlord
fails to provide such commercially reasonable non-disturbance agreements within
the time frame set forth in this Section 18.04, Tenant shall have the right,
exercisable at any time thereafter, to give five (5) business days' written
notice to Landlord terminating the Lease. In the event Landlord does not provide
Tenant with the applicable non-disturbance agreements within such five (5) day
period, the Lease shall terminated. Landlord agrees to provide Tenant with
non-disturbance agreement(s) in favor of Tenant from any Superior Mortgagee(s)
of Landlord who later come(s) into existence, in a form mutually agreed upon by
Tenant and such Superior Mortgagee at any time prior to the expiration of the
Term of the Lease, as it may be extended, in consideration of, and as a
condition precedent to, Tenant's agreement to be bound by Lease Article 18. Said
non-disturbance agreements shall be in recordable form and may be recorded, in a
form mutually agreed upon by Tenant and such Superior Mortgagee at Tenant's
election and expense.

                  Section 18.05. No act or failure to act on the part of
Landlord which would entitle Tenant under the terms of this Lease, or by law, to
be relieved of Tenant's obligations hereunder or to terminate this Lease, shall
result in a release of such obligations upon a termination of this Lease unless
(a) Tenant has given notice by registered or certified mail to any mortgagee or
lessor of Landlord whose address shall have been furnished to Tenant, and (b)
Tenant offers such mortgagee or lessor of Landlord a reasonable opportunity to
cure the default, including time to obtain possession of the Premises by power
of sale or judicial foreclosure, if such should prove necessary to effect a
cure.


                                     - 46 -
<PAGE>   53

                                   ARTICLE 19

                            SURRENDER OF THE PREMISES

         Section 19.01. Upon the Expiration Date or earlier termination of this
Lease, or upon any reentry of the Premises by Landlord without terminating this
Lease pursuant to Section 13.02(b). Tenant, at Tenant's sole cost and expense,
shall peacefully vacate and surrender the Premises to Landlord in good order,
broom clean and in the same condition as at the beginning of the Term or as the
Premises may thereafter have been improved by Landlord or Tenant (provided that
Tenant's improvements were made with Landlord's consent, if such consent shall
have been required), reasonable use and wear thereof, and casualty and repairs
which are Landlord's obligations under Articles 9, 15 and 16 only excepted, and
Tenant shall remove all Tenant's Property and turn over all keys for the
Premises to Landlord. Should Tenant continue to hold the Premises after the
expiration or earlier termination of this Lease, such holding over, unless
otherwise agreed to by Landlord in writing, shall constitute and be construed as
a tenancy at sufferance at monthly installments of Rent equal to one hundred
fifty percent (150%) of the monthly portion of Base Rent in effect as of the
date of expiration or earlier termination, and subject to all of the other
terms, charges and expenses set forth herein except any right to renew this
Lease or to expand the Premises. Subject to the provisions of Section 19.02
hereinbelow, Tenant shall also be liable to Landlord for all damage which
Landlord shall actually suffer because of any holding over by Tenant, and Tenant
shall indemnify Landlord against all claims made by any other tenant or
prospective tenant against Landlord resulting from delay by Landlord in
delivering possession of the Premises to such other tenant or prospective
tenant. The provisions of this Article 19 shall survive the expiration or
earlier termination of this Lease.

         Section 19.02. Notwithstanding anything to the contrary set forth
hereinbelow, Tenant shall have the right, upon the expiration of the original
Term of this Lease, or any extension thereof, to hold over in the Premises for
either a period of three (3) months, or six (6) months at Tenant's sole
election, upon the same terms and conditions that were applicable to the
Premises during the last month of the Term of the Lease, with Base Rent to be
based upon the amount Tenant was paying at the expiration of the Term for the
initial three (3) months holdover, but with Base Rent to be 125% of the then
current Base Rent for the additional three (3) month holdover by giving written
notice of such election to Landlord not less than six (6) months prior to the
scheduled Expiration Date, as it may be extended.



                                     - 47 -
<PAGE>   54

                                   ARTICLE 20

                           LANDLORD'S RIGHT TO INSPECT

         Section 20.01. Landlord shall retain duplicate keys to all doors of the
Premises. Tenant shall provide Landlord with new keys should Tenant receive
Landlord's consent to change the locks. After providing Tenant reasonable notice
of at least 24 hours (the "Access Notice"), Landlord shall have the right to
enter the Premises at reasonable hours, or in the event of cleaning the
Premises, after business hours, without notice, (or, in the event of an
emergency, at any hour, without notice) (a) to exhibit the same to present to
prospective mortgagees, lessors or purchasers during the Term and to prospective
tenants during the last year of the Term, (b) to inspect the Premises, (c) to
confirm that Tenant is complying with all of Tenant's covenants and obligations
under this Lease, (d) to clean or make repairs required of landlord under the
terms of this Lease, (e) to make repairs to areas adjoining the Premises, and
(f) to repair and service utility lines or other components of the Building;
provided, however, Landlord shall use reasonable efforts to minimize
interference with Tenant's business. Landlord shall not be liable to Tenant for
the exercise of Landlord's rights under this Article 20 and Tenant hereby waives
any claims for damages for any injury, inconvenience or interference with
Tenant's business, any loss of occupancy or quiet enjoyment of the Premises, and
any other loss occasioned thereby, except for bodily injury or property damage
resulting from the negligence or willful misconduct of Landlord or its agents,
contractors, employees, or licensees.

         Section 20.02. Landlord hereby acknowledges that the existence and
success of Tenant's business operations in the Premises require that Tenant be
allowed to employ strict security measures in connection with limiting access to
the Premises. Accordingly, Landlord agrees to comply with the Security Measures
(as defined below) in consideration for and as a condition precedent to Tenant
granting landlord the right to enter the Premises in accordance with this
Article 20. Tenant may designate certain portions of its Premises as "Limited
Access Areas" as Tenant deems necessary for the purpose of safeguarding Tenant's
confidential information and business operations and related equipment. Such
Limited Access Areas may include, but are not limited to, computer rooms, rooms
containing telecommunications and/or photocopy equipment, data rooms, libraries,
file rooms and areas containing conduits and/or ducting for Tenant's data lines.
Tenant has the right to keep the Limited Access Areas locked at all times. In
the event that Landlord needs to enter all or any portion of the Limited Access
Areas, Landlord shall provide Tenant with the Access Notice, in which Landlord
shall specify the name of the designated individual(s) (individually and
collectively, "Landlord's Designee") who Landlord proposes shall enter the
Limited Access Areas (or, in the case of an emergency, Landlord shall orally
communicate this information to Tenant), and Tenant shall, within twenty-four
(24) hours, either (a) approve of Landlord's Designee, or (b) reject Landlord's
Designee, in which case Landlord shall



                                     - 48 -
<PAGE>   55

designate a different individual as Landlord's Designee. Tenant hereby approves
of Christine Teagle as Landlord's Designee. As a condition to being granted
access to the Limited Access Areas, Landlord's Designee must comply with any
reasonable security measures required by Tenant ("Security Measures"), which
Security Measures may include, but are not limited to, being accompanied by an
authorized representative of Tenant, showing identification, signing in, and
wearing a security badge. Notwithstanding anything to the contrary set forth
above. Tenant may designate certain areas of the Premises as "Secured Areas"
should Tenant require such areas for the purpose of securing certain valuable
property or confidential information. Landlord may not enter such Secured Areas
except in the case of emergency or in the event of a Landlord inspection, in
which case landlord shall provide Tenant with five (5) days' prior written
notice of the specific date and time of such Landlord inspection. Tenant shall e
granted access to the Building, Parking Facility, Premises and the services and
utilities provided the Building 24 hours per day, 7 days per week.

                                   ARTICLE 21

                                SECURITY DEPOSIT

                              INTENTIONALLY DELETED

                                   ARTICLE 22

                                    BROKERAGE

         Section 22.01. Tenant and Landlord each represent and warrant to the
other that it has not entered into any agreement with, or otherwise had any
dealings with, any broker or agent in connection with the negotiation or
execution of this Lease which could form the basis of any claim by any such
broker or agent for a brokerage fee or commission, finder's fee, or any other
compensation of any king or nature in connection herewith, other than with
Broker and Prentiss Properties Limited, Inc., and each party shall, and hereby
agrees to, indemnify and hold the other harmless form all costs (including court
costs, investigation costs, and attorneys' fees), expenses, or liability for
commissions or other compensation claimed by any broker or agent with respect to
his Lease which arise out of any agreement or dealings, or alleged agreement or
dealings, between the indemnifying party and any such agent or broker, other
than with Broker. This provision shall survive the expiration or earlier
termination of this Lease. Tenant hereby agrees that Tenant shall pay broker a
brokerage commission pursuant to the terms of a separate agreement between
Broker and Tenant. Landlord hereby agrees that



                                     - 49 -
<PAGE>   56

Landlord shall pay Prentiss Properties Limited, Inc. a brokerage commission
pursuant to the terms of a separate agreement between Prentiss Properties
Limited, Inc. and Landlord.

                                   ARTICLE 23

                       OBSERVANCE OF RULES AND REGULATIONS

         Section 23.01. Tenant and Tenant's servants, employees, agents,
visitors, and licensees shall observe faithfully and comply strictly with all
Rules and Regulations (herein so called) attached to this Lease as such Rules
and Regulations may reasonably changed from time to time. Landlord shall at all
times have the right to make reasonable changes in and additions to such Rules
and Regulations; provided Landlord gives Tenant prior notice of such changes and
provided such new rules and regulations or changes in existing rules and
regulations did not conflict with this Lease, and do not materially interfere
with the lawful conduct of Tenant's business in the Premises. Any failure by
landlord to enforce any of the Rules and Regulations now or hereafter in effect,
either against Tenant or any other tenant in the Building, shall not constitute
a waiver of any such Rules and Regulations. Landlord shall not enforce the Rules
and Regulations in an unreasonable manner or in a manner which shall
unreasonably interfere with the normal and customary use of the Premises by
Tenant for normal and customary business office operations. Landlord shall not
be liable to Tenant for the failure or refusal by any other tenant guest,
invitee, visitor, or occupant of the Building to comply with any of the rules
and Regulations, but Landlord shall use commercially reasonable efforts to
enforce, and shall uniformly enforce, the Rules and Regulations.

                                   ARTICLE 24

                                     NOTICES

                  Section 24.01. All notices, consent, demands, requests,
documents, or other communications (other than payment of Rent) required or
permitted hereunder (collectively, "notices") shall be deemed given, whether
actually received or not, when dispatched for hand delivery or delivery by air
express courier (with signed receipts) to the other party, or on the second
Business Day after deposit in the United States mail, postage prepaid,
certified, return receipt requested, except for notice of change of address
which shall be deemed given only upon actual receipt. The addresses of the
parties for notices are set forth in Article 1, or any such other addresses
subsequent specified by each party in notices given pursuant to this Section
24.01.




                                     - 50 -
<PAGE>   57

                                   ARTICLE 25

                                  MISCELLANEOUS

                  Section 25.01. Professional Fees. In any action or proceeding
by either party against the other under this Lease, the prevailing party shall
be entitled to recover from the other party its professional fees for attorneys,
appraisers and accountants, its investigation costs, and any other legal
expenses and court costs incurred by the prevailing party in such action or
proceeding.

                  Section 25.02. Reimbursements. Except as otherwise set forth
in Articles 7, 9, and 10 of the Lease, wherever the Lease requires Tenant to
reimburse Landlord for the cost of any item which Tenant has elected to obtain
from Landlord, such costs will be the reasonable and customary charge
periodically established by Landlord for such item. Landlord shall keep in its
on-site manager's office a schedule of such charges (which Landlord may
periodically change) for Tenant's examination. The schedule of charges may
include, at the discretion of Landlord, a reasonable allocation of overhead,
administrative, and related costs and a reasonable fee, not to exceed five
percent (5%) of the cost of providing such services, for Landlord's agent or
manger who performs such services or arranges for performance of such services.
All such charges shall be payable within thirty (30) days after invoicing for
such costs as Additional Rent.

                  Section 25.03. Severability. Every agreement contained in this
Lease is, and shall be construed as, a separate independent agreement. If any
term of this Lease or the application thereof to any person or circumstances
shall be invalid or unenforceable, the remaining agreements contained in this
Lease shall not be affected.

                  Section 25.04. Non-Merger. There shall be no merger of this
Lease with any ground leasehold interest or the fee estate in the Project or any
part thereof by reason of the fact that the same person may acquire or hold,
directly or indirectly, this Lease or any interest in this Lease as well as any
ground leasehold interest or fee estate in the Project or any interest in such
fee estate.

                  Section 25.05. Landlord's Liability. Anything contained in
this Lease to the contrary notwithstanding, Tenant agrees that Tenant shall look
solely to the estate and property of Landlord in the Project for the collection
of any judgment or other judicial process requiring the payment of money by
Landlord for any default or breach by Landlord under this Lease, subject,
however, to prior rights of any mortgagee or lessor of the Project. No other
assets of Landlord or any partners, shareholders, or other principals of
Landlord shall be subject to levy, execution or other judicial process for the
satisfaction of Tenant's claim.

                  Section 25.06. Force Majeure. Whenever the period of time is
herein prescribed for action to be taken by Landlord or Tenant, or Tenant shall
not



                                     - 51 -
<PAGE>   58

be liable or responsible for, and there shall be excluded from the computation
of any such period of time, any delays due to force majeure, which term shall
include strikes, lockouts, or other labor or industrial disturbances, civil
disturbances, or riots, blockades, embargoes, sabotage, acts of God, shortages
of labor or materials, war, governmental approvals, laws, or changes in laws,
regulations, or restrictions, weather related delays, or any other cause of any
kind whatsoever which is beyond the reasonable control of Landlord or Tenant.
Force Majeure shall not excuse or delay Tenant's obligation to Rent or any other
amount due under this Lease.

                  Section 25.07. Headings. The article headings contained in
this Lease are the convenience only and shall enlarge or limit the scope or
meaning of the various and several articles hereof. Words in the singular number
shall be held to include the plural, unless the context otherwise requires. All
agreements and covenants herein contained shall be binding upon the respective
heirs, personal representatives, and successors and assigns of the parties
thereto.

                  Section 25.08. Successors and Assigns. All agreements and
covenants herein contained shall be binding upon the respective heirs, personal
representatives, successors and assigns or the parties hereto. If there be more
than one Tenant, the obligations hereunder imposed upon Tenant shall be joint
and several. If there is a guarantor of Tenant's obligations hereunder. Tenant's
obligations shall be joint and several obligations of Tenant and such guarantor,
and Landlord need not first proceed against Tenant hereunder before proceeding
against such guarantor, and any such guarantor shall not be released from its
guarantee for any reason, including any amendment of this Lease, any forbearance
by Landlord or waiver of any of Landlord's rights, the failure to give Tenant or
such guarantor any notices, or the release of any party liable for the payment
or performance of Tenant's obligations hereunder. Notwithstanding the foregoing,
nothing contained in this Section 25.08 shall be deemed to override Article 8.

                  Section 25.09. Landlord's Representations. Neither Landlord
nor Landlord's agents or brokers have made any representations or promises with
respect to the Premises, the Building, the Parking Facilities, the Land, or any
other portions of the Project except as herein expressly set forth and all
reliance with respect to any representations or promises is based solely on
those contained herein. No rights, easements, or licenses are acquired by Tenant
under this Lease by implication or otherwise except as, and unless, expressly
set forth in this Lease.

                  Section 25.10. Entire Agreement; Amendments. This Lease and
the Exhibits and Riders attached hereto set forth the entire agreement the
parties and cancel all prior negotiations, arrangements, brochures, agreements,
and understandings, if any, between Landlord and Tenant regarding the subject
matter of this Lease. No amendment or modification of this Lease shall be
binding or valid unless expressed in writing executed by both parties hereto.





                                     - 52 -
<PAGE>   59

                  Section 25.11. Tenant's Authority. If either Landlord or
Tenant (the "signing party") signs as a corporation, execution hereof shall
constitute a representation and warranty by the signing party that the singing
party is duly organized and existing corporation, that the signing party has
been and is qualified to do business in the State of Texas and in good standing
with the State of Texas, that the corporation has full right and authority to
enter in this Lease, and that all persons singing on behalf of the corporation
were authorized to do so by appropriate corporate action. If the signing party
signs as a partnership, trust, or other legal entity, execution hereof shall
constitute a representation and warranty by the signing party that the signing
party has complied with all applicable laws, rules and governmental regulations
relative to the signing party's right to do business in the State of Texas, that
such entity has the full right and authority to enter into this Lease, and that
all persons signing on behalf of the signing party were authorized to do so by
and all necessary or appropriate partnership, trust, or other actions.

                  Section 25.12. Governing Law. This Lease shall be governed by
and construed under the laws of the State of Texas. Any action brought to
enforce or interpret this Lease shall be brought in the court of appropriate
jurisdiction in Dallas County, Texas. Should any provision of this Lease require
judicial interpretation. Landlord and Tenant hereby agree and stipulate that the
court interpreting or considering same shall not apply the presumption that the
terms hereof shall be more strictly construed against a party by reason of any
rule or conclusion that a document should be construed more strictly against the
party who itself or through its agents prepared the same, it being agreed that
all parties hereto have participated in the preparation of this Lease and that
each party had full opportunity to consult legal counsel of its choice before
the execution of this Lease.

                  Section 25.13. Tenant's Use of Name of the Building. Tenant
shall not, without the prior written consent of Landlord, use the name of the
Building for any purpose other than as the address of the business to be
conducted by Tenant in the Premises, and Tenant shall not do or permit the doing
of anything in connection with Tenant's business or advertising (including
brokers' flyers promoting sublease space) which in the reasonable judgment of
Landlord may affect unfavorably on Landlord or the Building or confuse or
mislead the public as to any apparent connection or relationship between Tenant
and Landlord, the Building or the Land.

                  Section 25.14. Ancient Lights. Any elimination or shutting of
light, air, or view by any structure which may be erected on lands adjacent to
the Building shall in no way affect this Lease and Landlord shall have no
liability to Tenant with respect thereto.



                                     - 53 -
<PAGE>   60

                  Section 25.15. Changes to Project by Landlord. Landlord shall
have the unrestricted right to make changes to all portions of the Project in
Landlord's reasonable discretion for the purpose of improving access or security
to the Project or the flow of pedestrian and vehicular traffic therein. Landlord
shall have the right at any time, without the same constituting any actual or
constructive eviction and without incurring any liability to Tenant therefor, to
change the arrangement or location of entrances or passageways, doors and
doorways, corridors, elevators, stairs, bathrooms, or any other Common Areas so
long as reasonable access to the Premises remains available and Tenant's use and
quiet enjoyment of the Premises may not be materially and adversely affected.
Landlord shall also have the right to (a) rearrange, change, expand or contract
portions of the Project constituting Common Areas (b) to use Common Areas while
engaged in making improvements, repairs or alterations to the Project or any
portion thereof, and (c) to do and perform such other acts and make such other
changes in to or with respect to the Project, or any portion thereof, as
Landlord may, in the exercise of sound business judgment, deem to be
appropriate. Landlord shall be entitled to change the name or address of the
Building or the Project. Landlord shall have the right to close, from time to
time, the Common Areas and other portions of the Project for such temporary
periods as Landlord deems legally sufficient to evidence Landlord's ownership
and control thereof and to prevent any claim of adverse possession by, or any
implied or actual dedication to, the public or any other party other than
Landlord. The rights of Landlord's set forth herein shall be subject to Tenant's
access to the Premises remaining reasonably available and to Tenant's use and
quiet enjoyment of the Premises not being materially and adversely affected.

                  Section 25.16.    Time of Essence.  Time is of the essence of
this Lease.

                  Section 25.17. Landlord's Acceptance of Lease. The submission
of this Lease to Tenant shall not be construed as an offer and Tenant shall not
have any rights with respect thereto unless said Lease is consented to by
mortgagee, and any lessor of Landlord, to the extent such consent is required,
and Landlord executes a copy of this Lease and delivers the same to Tenant.

                  Section 25.18. Performance by Tenant. All covenants and
agreements to be performed by Tenant under any of the terms of this Lease shall
be performed by Tenant, at Tenant's sole cost and expense, and without any
abatement of Rent, except as set forth in Sections 3.01, 7.03, and 19.05 and
Articles 15 and 16 and Exhibit C herein. If Tenant shall fail to pay any Rent,
other than Base Rent, required to be paid by it hereunder or shall fail to
perform any other act on its part to be performed hereunder, and such failure
shall continue for longer than the period of cure, if any, permitted in Section
13.01, and Tenant shall not otherwise have the right to not pay any Rent or
perform any action on Tenant's part to be performed hereunder. Landlord may, at
its option, without waiving or releasing Tenant from obligations of Tenant, make
any such payment or perform



                                     - 54 -
<PAGE>   61

any such other act on behalf of Tenant. All sums so paid by Landlord and all
necessary incidental costs, together with interest thereon at the Interest Rate,
from the date of such payment by Landlord, shall be payable to Landlord on
demand. Tenant covenants to pay any such sums, and Landlord shall have (in
addition to any other right or remedy of Landlord) the same rights and remedies
in the event of the non-payment thereof by Tenant as in the case of default by
Tenant in the payment of Rent.

                  Section 25.19. Financial Statements. At any time during the
term of this Lease, Tenant shall, upon ten (10) days prior written notice from
Landlord, provide Landlord with an annual report and an annual report of the two
(2) years prior to the current year.

                  Section 25.20. Late Payments. Except with respect to the late
payment of Rent (which shall be governed by the provisions of Section 4.02),
whenever one party is obligated pursuant to this Lease to make a payment to the
other party, if such payment is not paid when due, then the party who does not
make such payment when due shall pay interest at the Interest Rate (as such term
is defined in Section 4.02) to the party on the unpaid amount from the date such
amount was due until the date such amount is paid.

                  Section 25.21. Time for Payments. Whenever in this Lease a
payment is required to be made by one party to the other, but a specific date
for payment is not set forth or a specific number of days within which payment
is to be made is not set forth, or the words "immediately", "promptly" and/or
"on demand", or the equivalent, are used to specify when such payment is due,
then such payment shall be due thirty (30) days after the party which is
entitled to such payment sends written notice to the other party demanding
payment.

                                   ARTICLE 26

                               SUBSTITUTION SPACE

                              INTENTIONALLY DELETED

                                   ARTICLE 27

                                OTHER DEFINITIONS

                  When used in this Lease, the terms set forth hereinbelow shall
have the following meanings: (a) "Business Days" shall mean Monday thorough
Friday (except for Holidays); "Business Hours" shall mean 8:00 a.m. to 6:00 p.m.
on



                                     - 55 -
<PAGE>   62

Monday through Friday and 9:00 a.m. to 1:00 p.m. on Saturdays (except for
Holidays); and "Holidays" shall mean those holidays designated by Landlord,
which holidays shall be consistent with those holidays designated by landlords
of other first-class office buildings in the North Dallas suburban area. (b)
"Common Areas" shall mean those certain areas and facilities of the Building and
the Parking Facilities and those certain improvements to the Land which are from
time to time provided by Landlord for the use of tenants of the Building and
their employees, clients, customers, licensees and invitees or for use by the
public, which facilities and improvements include any and all corridors,
elevator foyers, vending areas, bathrooms, electrical and telephone rooms,
mechanical rooms, janitorial areas and other similar facilities of the Building
and of the Parking Facilities and any and all grounds, parks, landscaped areas,
outside sitting areas, sidewalks, walkways, tunnels, pedestrianways, skybridges,
and generally all other improvements located on the Land, or which connect the
Land to other buildings. (c) The words "day" or "days" shall refer to calendar
days, except where "Business Days" are specified. (d) The words "herein",
"hereof", "hereby", "hereunder" and words of similar import shall be construed
to refer to this Lease as a whole and not to any particular Article or Section
thereof unless expressly so stated. (e) The words "include" and "including"
shall be construed as if followed by the phrase "without being limited to." (f)
"Net Rentable Area" shall mean (1) in the case of a single tenancy floor, all
floor area measured from the inside surface of the outer glass of the Building,
excluding only the areas ("Service Areas") within the outside wall used for the
Building's stairs, fire towers, elevator shafts, vertical penetrations of the
Building's central atrium, flues, vents, stacks, pipe shafts, and vertical ducts
(which areas shall be measured from the mid-point of walls enclosing such areas,
except for the Building's central atrium, which shall be measured from the
inside surface (with respect to the Premises) of the glass enclosing such
atrium) but including any Service Areas which for the specific use of the
particular tenant, such as special stairs or elevators, plus an allocation of
the square footage of the Building's central areas for providing telephone,
electrical, mechanical, janitorial, security and mail services, as well as, the
central entry lobby, ground level elevator lobby and service elevator lobby,
central fire exit corridors, service exit corridor and central loading dock (the
"Central Areas"), and (2) in the case of a floor to be occupied by more than one
tenant, all floor areas within the inside surface (with respect to the Premises)
of the glass enclosing vertical penetrations of the Building's central atrium,
and to the midpoint of the walls separating areas leased by or held for lease to
other tenants or from the Common Areas, but including a proportionate part of
the Common Areas located on such floor based upon the ratio which Tenant's Net
Rentable Area (excluding Common Areas) on such floor bears to the aggregate Net
Rentable Area (excluding Common Areas) on such floor, plus an allocation of the
square footage of the Building's Central Areas. In the case of both single and
multiple tenant floors, telephone, electrical, mechanical, maintenance,
janitorial or security rooms no included in the Building's Central Areas but
which service more than one floor shall be considered Common Areas and shall be
allocated among all tenants whose premises are served thereby, regardless of
whether such premises are located on the



                                     - 56 -
<PAGE>   63

same floor as the rooms in question. Such allocation shall be made in accordance
with the proportion of the Net Rentable Area so served. No deductions from Net
Rentable Area shall be made for columns or projections necessary to the
Building. Net Rentable Area of the Building shall include office and retail
space; it being understood, however, that the foregoing formula to be used in
the calculation of the Net Rentable Area of office space shall not necessarily
be the formula used by Landlord to calculate the Net Rentable Area of any retail
space in the Building, (g) Reference to Landlord as having "no liability to
Tenant" or being "without liability to Tenant" or words of like import shall
mean that Tenant is not entitled to terminate this Lease, or to claim actual or
constructive eviction, partial or total, or to receive any abatement or
diminution of rent, or to be relieved in any manner of any of Tenant's other
obligations hereunder, or to be compensated for loss or injury suffered or to
enforce any other right or kind of liability whatsoever against Landlord under
or with respect to this Lease or with respect to Tenant's use or occupancy of
the Premises. (h) A "repair" shall be deemed to include such rebuilding,
replacement and restoration as may be necessary to achieve and maintain good
working order and condition. (i) The "termination of this Lease" and words of
like import includes the expiration of the Term or the cancellation of this
Lease pursuant to any of the provisions of this Lease or to law. Upon the
termination of this Lease, the term shall end at 11:59 p.m. on the date of
termination as if such date were the Expiration Date, and neither party shall
have any further obligation or liability to the other after such termination
except (i) as shall be expressly provided for in this Lease and (ii) for such
obligations as by their nature or under the circumstances can only be, or by the
provisions of this Lease, may be, performed after such termination and, in any
event, unless expressly otherwise provided in this Lease, any liability for a
payment (which shall be apportioned as of the date of such termination) which
shall have accrued to or with respect to any period ending at the time of
termination shall survive the termination of this Lease. (j) the "terms of this
Lease" shall be deemed to include all terms, covenants, conditions, provisions,
obligations, limitations, restrictions, reservations and agreements contained in
this Lease. (k) "Tenant" shall be deemed to include Tenant's successors and
assigns (to the extent permitted by Landlord) and any and all occupants of the
Premises permitted by Landlord and claiming by, through or under Tenant. (l) A
"year" shall mean a calendar year.

                                   ARTICLE 28

                        BUILDING NAME AND TENANT SIGNAGE

                  Section 28.01. Landlord reserves the right, subject to the
provisions of this Section 28.01, at any time to change the name, insignia,
logotype, or street address of the Building without in any manner being liable
to Tenant; provided, however, that Landlord shall promptly reimburse Tenant for
up to $10,000.00 for any reasonable costs incurred by Tenant as a result of any
such



                                     - 57 -
<PAGE>   64

change (including, without limitation, costs incurred in replacing stationery
and business cards and advertising materials) except to the extent that any such
change was mandated by a governmental entity; and also provided, however,
Landlord shall not change the name of the Building to the name of a company
whose primary business shall be an internet access provider.

                  Section 28.02. (a) Tenant, at Tenant's sole cost and expense,
shall be entitled to install appropriate signage, which signage, at Tenant's
option, may be illuminated but shall not be neon signage, including Tenant's
corporate name and logo, on and in the Building, including (i) exterior Building
signage identifying Tenant on the top spandrel of the Building, (ii) at the
entry to the Building, and (iii) on the directory board located in the main
entrance to the Building. All such signage shall be subject to Landlord's
reasonable approval as to size, configuration, design, materials, and location.

                           (b)      Landlord shall, using Landlord's reasonable
efforts, cooperate with Tenant in obtaining the proper governmental approvals
and permits for the requested signage. All signage shall comply with building
codes or ordinances of the City of Farmers Branch, Texas. Any such signage
installed by Tenant need not be consistent or compatible with the Building's
design, signage and graphics program, but such inconsistent signage shall be
subject to Landlord's reasonable approval. Tenant shall be solely responsible
for the removal of its signs, and the cost of repairing any resulting damage to
the Building and/or Premises, upon the termination or assignment of the Lease.
To Landlord's knowledge, Landlord knows of no signage restrictions imposed by
governmental authorities which would prohibit Tenant from installing signage
similar to the signage located on the 1601 and 1603 LBJ Freeway, Dallas, Texas
buildings.

                                   ARTICLE 29

                                 NON-COMPETITION

                  Section 29.01. Landlord warrants and agrees that: (a) Landlord
will not provide any signage on, in or around the Building (excluding standard
lobby directory board listings) to any Competitor of Tenant (as hereinafter
defined) throughout the entire Term of the Lease and any extension thereof; (b)
no other tenant or occupant of the Building shall have, or be provided with,
better signage than what is provided to Tenant; (c) Landlord shall not name the
Building after any Competitor of Tenant; and (d) no other identification or name
of any other tenant or occupant of the Building shall be located above Tenant's
identification on such Building signage or be in larger or more prominent
letters. In the event that Landlord violates any of its agreements set forth in
(a), (b), (c) and (d) of the preceding sentence, Tenant shall have, in addition
to all other rights and remedies



                                     - 58 -
<PAGE>   65

which it may have under this Lease or at law, the right to injunctive relief
against Landlord for such breach.

                  Section 29.02. Landlord agreements that it will not, during
the Term of the Lease (as it may be extended) lease any space in the Building to
any other tenant, or consent to a sublease or an assignment, to any other person
or entity whose primary business is predominantly based in the computer/internet
service provider industry ("Competitor"). In the event that Landlord violates
its agreement set forth in this Section, Tenant shall have, in addition to all
other remedies which it may have under this Lease or at law, the right to
injunctive relief against Landlord for such breach.

                                   ARTICLE 30

                            ANTENNA AND HVAC SYSTEMS

                  Section 30.01. During the Term of the Lease (as it may be
extended). Tenant shall have the right to install and maintain, on the roof of
the Building, satellite dishes, television antennas, related receiving
equipment, related cable connections and any and all other related equipment
(collectively, "Satellite Dish") required in connection with Tenant's
communications and data transmission network, subject to Landlord's reasonable
approval and the design constraints of the Building. Tenant shall have the right
to use "risers" in the Building (and to install additional risers if necessary)
to the extent of availability of space in such risers, as long as there is no
adverse affect on the building Structure or Building System. In addition to the
foregoing, Tenant shall at its option exercisable by a thirty (30) days' notice
to Landlord, have the right to use additional space on the roof of the Building
for Tenant's additional HVAC equipment and any and all related equipment to
accommodate Tenant's excess HVAC requirements (collectively, "HVAC Unit"),
subject to Landlord's reasonable approval and the design constraints of the
Building. The proposed construction and installation and general appearance of
the Satellite Dish shall be mutually agreed upon by Landlord and Tenant.
Furthermore, the exact location of any such Satellite Dish or HVAC Unit shall be
mutually acceptable to Landlord and Tenant and Tenant shall have secured the
approval of all governmental authorities and all permits required by
governmental authorities having jurisdiction over such approvals and permits for
the Satellite Dish and the HVAC Unit, and shall provide copies of such approvals
and permits to Landlord, prior to commencing any work with respect to such
Satellite Dish and the HVAC Unit. Tenant shall pay for any and all costs and
expenses in connection with the installation, maintenance, use and removal of
the Satellite Dish and the HVAC Unit, but in no event shall Tenant be obligated
to pay Landlord any rental for that portion of the roof of the Satellite Dish
and the HVAC Unit shall be located. Furthermore, Tenant shall, at its sole and
absolute discretion when it deems it as necessary or appropriate to do so,
repair and maintain the



                                     - 59 -
<PAGE>   66

Satellite Dish and the HVAC Unit, but Tenant may not enter upon the roof of the
Building for such repair without providing at least one (1) business days'
notice to Landlord (except in the case of an emergency where no advance notice
shall be required. Upon the expiration of the Term of the Lease. Tenant shall
remove the Satellite Dish and the HVAC Unit and repair any damage to the roof
resulting therefrom.

                                   ARTICLE 31

              RIGHT TO TERMINATE FOR FAILURE TO PROVIDE SERVICES OR
                          DUE TO HAZARDOUS SUBSTANCES

                  Section 31.01. Notwithstanding anything to the contrary, and
except as expressly set forth in Section 30.02 below, in the event that tenant
is notified or becomes aware of the fact that as a result of:

                           (a)      the inability of Landlord to provide
services to the Premises, or a substantial portion of the Premises, the Parking
Facility and/or the Building so as to render the Premises, the Parking Facility
and/or the Building unusable, such that Tenant does not use the Premises for the
Non-Use Period (hereinafter defined); or

                           (b)      any discovery of hazardous substances in, or
around the Premises, the Building and/or the Land not placed in, in or around
the Premises, the Building and/or the Land by Tenant, that may, considering the
nature and amount of the substances involved, render the Premises unusable by
Tenant, such that Tenant does not use the Premises for the Non-Use Period;
which present a health risk to any occupants of the Premises) (each of the items
set forth in this Section 31.01(a) and (b) being referred to herein as a
"Trigger Event").

                           Tenant cannot, within six (6) months ("Non-Use
Period") of the occurrence of the Trigger Event, be given reasonable use of, and
access to, a fully repaired, restored. safe and healthful Premises, Parking
Facility and Building (except for minor "punch-list" items which will be
repaired promptly thereafter), and the utilities and services pertaining to the
Premises, the Parking Facility and the Building, all suitable for the efficient
conduct of Tenant's business therefrom, then Tenant may elect to exercise an
on-going right to terminate the Lease upon thirty (30) days' written notice sent
to Landlord at any time following the expiration of the Non-Use Period.

                  Section 31.02. In the event of any Trigger Event occurring
during the last year of the Term or, if an applicable renewal option has been
exercised, during the last year of any renewal term, should the Non-Use Period
continue for ninety (90) days. Tenant may elect to exercise an on-going right to
terminate the





                                     - 60 -
<PAGE>   67

Lease upon thirty (30) days' written notice sent to Landlord at any time
following the expiration of the Non-Use Period.

                           [SIGNATURE PAGE TO FOLLOW]




                                     - 61 -
<PAGE>   68

                  IN WITNESS WHEREOF, Landlord and Tenant have set their hands
and seals hereto and have caused this Lease to be executed by duly authorized
officials thereof, as of the day and year set forth on the cover page hereof.

LANDLORD:

Park West E-3 Associates.
a Texas joint venture

         By: The Prentiss/Copley Investment Group.
         a Delaware joint venture

                  By: Prentiss Property Investments, L.P.,
                  a Delaware limited partnership

                           By: Prentiss Property Investments. Inc..
                           a Delaware corporation


                           By:  /s/ DENNIS J. DUBOIS
                              ---------------------------------------
                           Name:    Dennis J. Dubois
                                -------------------------------------
                           Title:   Principal
                                 ------------------------------------

                           By:  /s/ J. KEVAN DILBECK
                              ---------------------------------------
                           Name:    J. Kevan Dilbeck
                                -------------------------------------
                           Title:   Vice President
                                 ------------------------------------

TENANT

NETCOM On-Line Communications Services, Inc.,
a Delaware Corporation

By:  /s/ C. THOM WEATHERFORD
   ---------------------------------------
Name:    C. Thom Weatherford
     -------------------------------------
Title:     Chief Financial Officer
      ------------------------------------


By:  /s/ ANITA ALSTON
   ---------------------------------------
Name:    Anita Alston
     -------------------------------------
Title:   Director of Corporate Real Estate
   ---------------------------------------



                                     - 62 -
<PAGE>   69

                                    EXHIBIT A

                           FLOOR PLAN OF THE PREMISES

                                    (DRAWING)






                                     - A -
                                    Solo Page

<PAGE>   70

                                    EXHIBIT B

                                    THE LAND

                  Lot 5. Block 1. of Park West Phase II,. according to the Plat
thereof recorded in the real property records of Dallas County, Texas, as such
property may he replatted from time to time.







                                      - B -
                                    Solo Page

<PAGE>   71

                                    EXHIBIT C

                             LEASEHOLD IMPROVEMENTS

                                    ARTICLE I

                                   DEFINITIONS

         The terms defined in Article I of this Exhibit C, for all purposes of
this Exhibit C, shall have the meanings herein specified, and in addition to the
terms defined herein, the definitions in Section 1.01 of the Lease and otherwise
in this Lease shall also apply to this Exhibit C.

         1.01. "Base Building Condition" shall mean the "as is" condition of the
Premises completed with the following improvements, all of which improvements
have been previously completed in the Premises; (a) outside walls, core walls,
columns, and ground elevator lobby areas completed to Building Standard
condition for public areas; (b) broom clean, unfinished concrete floors
throughout the Premises; (c) Building Standard ceiling grid system installed
throughout, with ceiling tile stacked on floor; (d) Building Standard 110 Volt
20 amp. power supplied to the Building core, at panels in the electrical closet;
(e) men's and ladies' restroom facilities with Building Standard finishes
located on each floor on which the Premises are located; (f) main heating,
ventilating, and air-conditioning ducts completed to the mixing boxes, and
standard thermostats, connected in ceiling; (g) sprinkler risers and main loop
on each floor; and (h) Building Standard smoke detectors in accordance with
applicable building codes and based on an open office floor plan.

         1.02. "Building Standard" means the quality of materials, finishes, and
workmanship from time to time specified by Landlord for the Building.

         1.03. "Non-Building Standard" means all materials, finishes, and
workmanship used in connection with the construction and installation of
Leasehold Improvements which deviate from Building Standard in terms of quality.

         1.04. "Tenant's Work" means the work which is supplied, installed, and
finished by Landlord's Contractor, at Tenant's cost, to complete any leasehold
improvements to the Premises.

         1.05. "Leasehold Improvements" shall mean the leasehold improvements,
both existing, if any, and to be completed, in the Premises.


                                        C
                                  Page 1 of 8
<PAGE>   72

         1.06. "Tenant's Space Planner" shall mean the architect or space
planner engaged by Tenant to prepare the plans and specifications for the
Leasehold Improvements as contemplated by Article 2 hereof.

         1.07. "Landlord's Contractor" means the person or firm from time to
time selected by Landlord and Tenant, in accordance with the provisions of
Section 2.02 hereof, and paid by Tenant to construct and install the Leasehold
Improvements in the Premises.

         1.08. "Landlord's Manager" shall be the manager of the Building, whose
responsibilities include serving as construction manager for Tenant in
connection with the construction of the Leasehold Improvements.

         1.09. "Net Rentable Area of the Building" shall have the meaning
specified in Section 1.01 of the Lease.

         1.10. "Net Rentable Area of the Premises" shall have the meaning
specified in Section 1.01 of the Lease.

         1.11. "Substantially Complete" or Substantial Completion" shall mean
(a) all of the Building Systems are operational to the extent necessary to
service the Premises and the shell and core of the Building are complete and all
Building Systems are operational to the extent necessary to service the
Premises; (b) Landlord has sufficiently completed all the work required to be
performed by Landlord in accordance with this Lease (except punch list items
which Landlord shall thereafter promptly complete) such that Tenant can conduct
normal business operations from the Premises; (c) Landlord has obtained a
certificate of occupancy for the Building, or a temporary certificate of
occupancy for that portion of the Building that includes all of the Premises,
(d) Tenant has been provided with the number of parking spaces to which it is
entitled under the Lease; (e) Tenant has been delivered complete and
uninterrupted access to the Premises (and other required portions of the
Building and the Common Areas) sufficient to allow Tenant to install its
freestanding work stations, fixtures, furniture, equipment, and
telecommunication and computer cabling systems and to move into the Premises
over one (1) weekend; and (f) Tenant has received the Non-Disturbance Agreement
signed by Landlord and each lienholder, ground lessor, or mortgage holder of
record, as required by the Lease.

         1.12. "Tenant Expenditures Authorization" means an authorization by
Tenant, prior to the commencement of any Tenant's Work for Landlord's Manager to
contract to expend funds on behalf of Tenant.

         1.13. "Landlord Delay" shall mean any delay in the approval of the
design of the Leasehold Improvements or Tenant's move-in into the Premises
during the


                                        C
                                  Page 2 of 8
<PAGE>   73

Move-In Period which is due to an act or omission of Landlord (wrongful,
negligent or otherwise), its agents or contractors (including acts or omissions
while acting as agent or contractor for Tenant). Landlord Delay shall include,
but shall not be limited to any; (a) delay in the giving of authorizations or
approvals by Landlord beyond prescribed review periods set forth in the Lease;
(b) delay attributable to the acts or failures to act, whether willful,
negligent or otherwise, of Landlord, its agents or contractors; (c) delay
attributable to the interference of Landlord, its agents or contractors with the
design of the Leasehold Improvements or the failure or refusal of any such party
to permit Tenant, its agent or contractors, access to and use of the Building or
any Building facilities or services, including elevators, and loading docks
which access and use are required for the orderly performance of the work
necessary for Tenant to complete its move-in into the Premises during the
Move-In Period, subject to reasonable restrictions imposed by Landlord or
Landlord's Contractor prior to Substantial Completion; (d) delay attributable to
Landlord giving Tenant incorrect or incomplete Building requirements or base
Building plans, or revisions made to such Building requirements or base Building
plans subsequent to the delivery of such items to Tenant (collectively,
"Incomplete Plans") in either case, in addition to such delay being deemed a
Landlord Delay. Landlord shall reimburse Tenant solely for the actual increased
costs incurred by Tenant as a result thereof; and (e) delay attributable to
Landlord's failure to allow Tenant sufficient access to the Building and/or the
Premises during the Move-In Period to move into the Premises over one (1)
weekend. In no event shall Tenant's remedies or entitlements for the occurrence
of a Landlord Delay be abated, deferred, diminished or rendered inoperative
because of a prior, concurrent, or subsequent delay resulting from any action or
inaction of Tenant, but any such Landlord Delay and Tenant Delay shall be offset
against each other.

         1.14. "Tenant Delay" shall mean any delay that Landlord may encounter
in the performance of Landlord's obligations under this Lease because of any act
or omission of any nature by Tenant or its agents or contractors, including, but
not limited to, any (a) delay attributable to failure to approve, or changes in
or additions to, the Plans and Specifications (as defined in Section 2.01 below)
or to the Leasehold Improvements requested by Tenant; (b) delay attributable to
the postponement of any Leasehold Improvements at the request of Tenant; (c)
delay by Tenant in the submission of information or the giving of authorizations
or approvals within the time limits set forth in this Lease; (d) delay
attributable to the failure of Tenant to pay, when due, any amounts required to
be paid by Tenant pursuant to this Lease; (e) delay caused by Tenant's failure
to approve the Tenant Expenditure Authorization (as defined in Section 1.12
hereof; and (f) Tenant's request for materials, finishes or installations, which
are other than Building Standard. No Tenant Delay shall be deemed to have
occurred unless and until Landlord provides notice to Tenant specifying the
action or inaction that Landlord contends constitutes, or could constitute a
Tenant Delay. If such action or inaction is not cured within one (1) day after
receipt of such notice, than a Tenant Delay, as



                                        C
                                  Page 3 of 8
<PAGE>   74

set forth in such notice, shall be deemed to have occurred, commencing as of the
date such notice is received and continuing for the number of days the
construction of the Leasehold Improvements was in fact delayed as a result of
such action or inaction.

                                    ARTICLE 2

                             COMPLETION OF PREMISES

         2.01. Tenant's Space Planner has prepared and completed, and Landlord
has approved, the space plan for the Premises. Tenant's Space Planner shall
complete the architectural construction plan with detailed specifications and
finish schedules and the mechanical and electrical construction plan with
detained specifications (collectively "Plans and Specifications") for the
Leasehold Improvements. Such Plans and Specifications shall be prepared by
Tenant's Space Planner and submitted, together with the Tenant Expenditure
Authorization, which has been prepared by Landlord's Manager, to Tenant for its
approval. Within ten (10) working days after Tenant's receipt of such Plans and
Specifications and the Tenant Expenditure Authorization, Tenant shall notify
Landlord's Manager in writing as to whether Tenant approves or disapproves such
Plans and Specifications and the Tenant Expenditure Authorization. Landlord
shall approve of such Plans and Specifications within ten (10) working days of
Landlord's receipt of same. Landlord's approval of the Plans and Specifications,
and any changes thereto, for Tenant's Work shall impose no responsibility or
liability on Landlord for their completeness, design sufficiency, or compliance
with all applicable laws, rules and regulations of governmental agencies or
authorities. If Tenant or Landlord fails to expressly disapprove such Plans and
Specifications and the Tenant Expenditure Authorization within this ten (10)
working day period, then Landlord's Manger shall be authorized to proceed
thereon. All costs, including professional fees, of Tenant's Space Planner which
are related to the review of Tenant's information and instructions and the
preparation of the space plan and the Plans and Specifications shall be paid by
Landlord.

         2.02. Landlord's Contractor shall be the contractor selected pursuant
to a procedure whereby the Plans and Specifications and a construction contract
approved by Tenant are submitted to three (3) contractors, selected by Landlord
and approved by Tenant, who are requested to each submit a sealed fixed price
contract bid price (on such contract form as Landlord shall designate) to
construct the Leasehold Improvements designated on the Plans and Specifications,
to Landlord and Tenant, who shall jointly open and review the bids. Landlord and
Tenant after adjustments for the inconsistent assumptions to reflect an "apples
to apples" comparison, shall select the lowest price qualified bidder and such
contractor with the lowest priced qualified bid shall be Landlord's Contractor
and shall enter into a construction contract with Landlord consistent with the
terms of the bid to



                                        C
                                  Page 4 of 8
<PAGE>   75

construct the Leasehold Improvements ("Construction Contract"); provided,
however, in the event the lowest priced qualified bid shall, in Tenant's
reasonable determination, be excessive in terms of costs. Tenant may, at its
option, revise the Plans and Specifications, and any delays caused by such
revisions and, if necessary, rebidding shall be a Tenant Delay. Such revised
Plans and Specifications shall then be subject to this Exhibit C. The
Construction Contract shall not, unless Tenant otherwise directs, require
Landlord's Contractor to post a completion bond or contain any provision
penalizing the Landlord's Contractor for not completing the Leasehold
Improvements within a specific period of time.

         2.03. All Tenant's Work involved in the construction and installation
of the Leasehold Improvements shall be carried out by Landlord's Contractor
under the sole direction of Landlord's Manager, who shall serve as construction
manager on behalf of Tenant. Tenant shall cooperate with Landlord and Tenant's
Space Planner to promote the efficient and expeditious completion of such
Tenant's Work. Tenant agrees to pay, promptly upon being billed therefor, the
cost (labor and materials) of all Tenant's Work, together with a fee of five
percent (5%) thereon to Landlord's Manager as compensation for Landlord's
Manager's supervision of the construction, alteration, and installation of the
Leasehold Improvements. Tenant shall select a project manager to serve as
Tenant's representative throughout the construction of the Leasehold
Improvements. Tenant's project manager shall be authorized to make all decisions
on behalf of Tenant regarding the construction of the Leasehold Improvements.
Landlord's Manager shall submit monthly statements of costs incurred to Tenant,
which statements shall be promptly paid by Tenant, with such final statement to
be due on or before Tenant occupies the Premises. Tenant agrees that in the
event of default of payment thereof, Landlord (in addition to all other
remedies) shall have the same rights as in the event of default of payment of
Rent under this Lease.

         2.04. In the event that Tenant requests any changes to the Plans and
Specifications, Landlord shall not unreasonably withhold its consent to any such
changes, and shall grant its reasonable consent to such changes within two (2)
business days after Landlord's receipt of same. If such changes increase the
cost of constructing the Leasehold Improvements shown on the Plans and
Specifications, Landlord shall provide Tenant with invoices documenting and
evidencing such increased costs, and Tenant shall pay for such increased costs
on a monthly basis according to the invoices for such costs provided by
Landlord's Contractor in accordance with the progress payment schedule. The
costs charged by Landlord to Tenant pursuant to this Section 2.04 shall be an
amount equal to the actual third party costs, if any, incurred by Landlord to
review the requested changes and to cause Tenant's Space Planner to revise the
Plans and Specifications.

         2.05. If there are any changes in the Leasehold Improvements caused by
Tenant from the work as reflected in the final Plans and Specifications, each
such


                                        C
                                  Page 5 of 8
<PAGE>   76

change must receive the prior written approval of the Landlord, and, in the
event of any such approved change in the Plans and Specifications, Tenant shall
cause Tenant's Space Planner, upon completion of the Tenant's Work, to furnish
Landlord with an accurate "as-built" plan of the Tenant's Work as constructed,
which plans shall be incorporated in to this Exhibit C by this reference for all
intents and purposes when said plans are fully completed.

         2.06 Under no circumstances whatsoever will Tenant, or Tenant's
authorized representative, ever alter or modify or in any manner disturb any
Building Systems, Building Structure, or installation of the Building. Only
under Landlord's express written permission and under direct supervision of
Landlord or Landlord's authorized representative shall Tenant or Tenant's
authorized representative alter or modify or in any manner disturb any branch of
any Building System or installation of the Building which is located within the
Premises including, but not limited to, branch electrical system, branch
heating, ventilating, and air-conditioning system and branch fire protection and
alert system.

         2.07. All design, construction and installation shall conform to the
requirements of applicable building, plumbing and electrical codes and the
requirements of any authority having jurisdiction over or with respect to, such
work.

         2.08. Landlord's Manager shall have no obligation to cause the
commencement of the installation of any of the Leasehold Improvements in the
Premises until Tenant shall have approved the Plans and Specification and the
Tenant Expenditure Authorization as required by Section 2.01 hereof.

         2.09. Tenant acknowledges that the Premises, and the existing Leasehold
Improvements, are delivered to Tenant, and accepted by Tenant, in "as is"
condition, except to the extent that Landlord causes Landlord's Contractor to
construct additional Leasehold Improvements to the Premises.

         2.10. After the Leasehold Improvements to the Premises are
Substantially Completed (excepting punch list items) and prior to Tenant's
move-in into the Premises ("First Time"), and within thirty (30) days after the
expiration of the Move-In Period ("Second Time"), in each case following five
(5) business days' advance written notice from Tenant to Landlord, Landlord
shall cause Tenant's Space Planner and Landlord's Contractor to inspect the
Premises with a representative of Tenant and complete a punch list of unfinished
items of the Leasehold Improvements. Authorized representatives for Landlord and
Tenant shall execute said punch list to indicate their approval thereof.
Landlord shall cause Landlord's Contractor to use reasonable efforts to complete
such punch list within thirty (30) days after the approval of such punch list,
or as soon thereafter as reasonably practicable.


                                        C

                                  Page 6 of 8
<PAGE>   77

         2.11. Landlord shall cause Landlord's Contractor to clean the Premises
prior to the commencement of the Move-In Period, including removal of all
rubbish and debris. The cleaning shall leave the Premises in a manner consistent
with the commencement of business from comparable premises in Comparable
Buildings, such that Tenant may commence its business operations from the
Premises immediately after Landlord's Contractor completes such clean-up,
subject to Tenant's move into the Premises. The cost of the cleaning provided by
Landlord's Contractor shall not be included in Operating Costs for the Building
prior to Tenant's occupancy of the Premises.

         2.12 Neither Tenant nor the Landlord's Contractor shall be charged for,
and Landlord shall provide, (a) parking (to the extent parking is available) for
Tenant's Space Planner and Tenant's architects, designers, contractors and
subcontractors (including those people working on the Leasehold Improvements)
and (b) utilities for the use of electricity, water, toilet facilities, HVAC,
security, or elevators, during the construction of the Leasehold Improvements or
during the Move-In Period. All such equipment, areas, elevators and utilities
shall be made reasonably available to Tenant during the Move-In Period.

         2.13. In the event that Landlord requires Tenant to use specified
contractors or entities (such as mechanical, electrical, plumbing, engineering,
or other contractors, all of whom will be deemed agents of Landlord), Landlord
shall cause such contractors or entities to charge Tenant for such work an
amount not to exceed the cost such contractors or entities charge Landlord for
similar work performed by Landlord's own account.

         2.14 During the period prior to the Commencement Date, Tenant shall
have the right, without the obligation to pay Rent, to use empty space in the
Building, if available, designated by Landlord for the sole purpose of storing
and staging its furniture and equipment. With respect to this free storage
space, Tenant shall be responsible for providing all insurance and for providing
any necessary protective facilities. Tenant shall hold Landlord harmless and
shall indemnify Landlord from and against any and all loss, liability or cost
arising out of or in connection with use of such storage space by Tenant. Tenant
shall be obligated to remove all of the stored materials and other facilities by
on or before the Commencement Date.

         2.15. Notwithstanding anything to the contrary contained in this
Exhibit C or the Lease, if construction costs related to the ADA exceed
$44,000.00, Tenant shall receive a credit against Rent for up to $22,000.00 of
such excess costs. All AD related construction costs in excess of $66,000.00
shall be solely borne by Tenant.

                                    ARTICLE 3

                                        C

                                  Page 7 of 8
<PAGE>   78

                              COMMENCEMENT OF RENT

                  3.01. The Commencement Data and Tenant's obligation for the
payment of the Rent under this Lease for the Premises shall commence in
accordance with the terms of Article 3 and Article 4, respectively of the Lease
subject to Landlord Delay, Tenant Delay, and Force Major (as defined in Section
25.06 of the Lease).


                                        C

                                  Page 8 of 8
<PAGE>   79
                                    EXHIBIT D

                           FORM OF COMMENCEMENT NOTICE

         This Commencement Notice is delivered this ___ day of _________, 19__,
by Park West E-3 Associates, a Texas joint venture ("Landlord") to ___________ 
("Tenant"), pursuant to the provisions of Section 3.03 of that certain Lease
Agreement (the "Lease") dated __________, 19__, by and between Landlord and
Tenant covering  certain space in the Building known as __________. All terms
used herein with  their initial letter capitalized shall have the meaning
assigned to such terms in the Lease.

                              W I T N E S S E T H:

         1. The Building, the Premises, the Parking Facilities, and all other
improvements required to be constructed and furnished by Landlord in accordance
with the terms of the Lease have been satisfactorily completed by the Landlord
and accepted by the Tenant.

         2. The premises have been delivered to, and accepted by, the Tenant,
subject to the completion of "punch list" items.

         3.       The Commencement Date of the lease is the 1st day of_________,
 19__, and the Expiration Date is the __ day of _____________, 19__.

         4.       The Premises consist of ___ square feet of Net Rentable Area
on the_____floor of the Building.

         5.       The Base Rent is $__________________________ per annum,
payable in monthly installments of $________________ and $_________________, 
respectively, subject, however, to the provisions of the Lease relating to
adjustments for Tenant's operating costs Payment.

         6. Remittance of the foregoing payments shall be made on the first day
of each month in accordance with the terms and conditions of the lease at the
following address:

                           Park West E-3 Associates
                           c/o Prentiss Properties Limited, Inc.
                           1717 Main Street, Suite 5000
                           Dallas, Texas  75201

         IN WITNESS WHEREOF, this instrument has been duly executed by Landlord
as of the date first written above.


                                        D
                                   Page 1 of 2


<PAGE>   80

LANDLORD:

Park West E-3 Associates,
a Delaware joint venture

         By:  Prentiss Property Investments, Inc.,
         a Delaware limited partnership

                  By:
                     -------------------------------
                  Name:
                       -----------------------------
                  Title:
                        ----------------------------

                  By:
                     -------------------------------
                  Name:
                       -----------------------------
                  Title:
                        ----------------------------


                                        D
                                   Page 2 of 2

<PAGE>   81


                                   RIDER NO. 1

                              RULES AND REGULATIONS

         1. Sidewalks, doorways, vestibules, halls, stairways and similar areas
shall not be obstructed by tenants or their officers, agents, servants, and
employees, or used for any purpose other than ingress and egress to and from the
Premises and for going from one part of the Building to another part of the
Building.

         2. Plumbing fixtures and appliances shall be used only for the purpose
for which constructed, and no sweepings, rubbish, rags, or other unsuitable
material shall be thrown or placed therein. The cost of repairing any stoppage
or damage resulting to any such fixtures or appliances from misuse on the part
of a tenant or such tenant's officers, agents, servants, and employees shall be
paid by such tenant.

         3. No signs, poster, advertisements, or notices shall be painted or
affixed on any of the windows or doors, or other part of the Building, except of
such color, size, and style, and in such places, as shall be first approved in
writing by the building manager. No nails, hooks, or screws shall be driven into
or inserted in any part of the Building, except by Building maintenance
personnel.

         4. Directories will be placed by Landlord, Landlord's own expense, in
conspicuous places in the Building. No other directories shall be permitted.

         5. The Premises shall not be used for conducting any barter, trade, or
exchange of goods or sale through promotional give-away gimmicks or any business
involving the sale of second-hand goods, insurance salvage stock, or fire sale
stock, and shall not be used for any auction or pawnshop business, any fire
sale, bankruptcy sale, going-out-of-business sale, moving sale, bulk sale, or
any other business which, because of the Building.

         6. Tenants shall not do anything, or permit anything to be done, in or
about the Building, or bring or keep anything therein, that will in any way
increase the possibility of fire or other casualty or obstruct or interfere with
the rights of, or otherwise injure or annoy, other tenants, or do anything in
conflict with the valid pertinent laws, rules, or regulations of any
governmental authority.

         7. Tenant shall not place a load upon any floor of the premises which
exceeds to floor load per square foot which such floor was designed to carry or
which is allowed by applicable building code. Landlord may prescribe the weight
and position of all safes and heavy installations which Tenant desires to place
in the premises so as properly to distribute the weight thereof. All damage done
to the Building by the improper placing of heavy items which overstress the
floor will be repaired at the sole expense of the Tenant.

                                       R-1
                                   Page 1 of 3
<PAGE>   82

         8. A tenant shall notify the building manager when safes or other heavy
equipment are to be taken into or out of the Building. moving of such items
shall be done under the supervision of the building manager, after receiving
written permission from him/her.

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

         10. All deliveries must be made via the service entrance and service
elevators during normal business hours or as otherwise directed or scheduled by
Landlord. prior approval must be obtained from Landlord for any deliveries that
must be received after normal business hours.

         11. Each tenant shall cooperate with building employees in keeping the
premises neat and clean.

         12. Nothing shall be swept or thrown into the corridors, halls,
elevator shafts, or stairways. No birds, animals, or reptiles, or any other
creatures, shall be brought into or kept in or about the building.

         13. Should a tenant require telegraphic, telephonic, annunciator, or
any other communication service, Landlord will direct the electricians and
installers where and how the wires are to be introduced and placed, and none
shall be introduced or placed except as Landlord shall direct.

         14. Tenants shall not make or permit any improper noises in the
Building, or otherwise interfere in any way with other tenants or persons having
business with them.

         15. No equipment of any kind shall be operated on the premises that
could in any way annoy any other tenant in the Building without written consent
of Landlord.

         16. Business machines and mechanical equipment belonging to tenant
which cause noise and/or vibration that may be transmitted to the structure of
the Building or to any leased space so as to be objectionable to Landlord or any
tenants in the Building shall be placed and maintained by Tenant, at Tenant's
expense, in setting of cork, rubber, or spring type noise and/or vibration
eliminators sufficient to eliminate vibration and/or noise.

         17. tenants shall not use or keep in the Building any inflammable or
explosive fluid or substance, or any illuminating material, unless it is battery
powered, UL approved.

         18. Tenant employees or agents, or anyone else who desires to enter the
Building after normal business hours, may be required to provide appropriate
identification and sign in upon entry, and sign out upon leaving, giving the
location

                                       R-1
                                   Page 2 of 3

<PAGE>   83

during such person's stay and such person's time of arrival and
departure, and shall otherwise comply with any reasonable access control
procedures as Landlord may from time to time institute.

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

         20. If any governmental license or permit shall be required for the
proper and lawful conduct of Tenant's business, tenant, before occupying the
Premises, shall procure and maintain such license or permit and submit it for
Landlord's inspection. tenant shall at all times comply with the terms of any
such license or permit.

         21. Landlord shall have the right, exercisable without notice and
without liability to any tenant, to change the name and street address of the
Building.

         22. Landlord serves the right to rescind any of these Rules and
Regulations and make such other and further rules and regulations not
inconsistent with the express terms of the lease as in the judgment of Landlord
shall form time to time be needed for the safety, protection, care, and
cleanliness of the Building, the operation thereof, the preservation of good
order therein, and the protection and comfort of its tenants, their agents,
employees, and invitees, which rules and Regulations when made and notice
thereof given to a tenant shall be binding upon him in like manner as if
originally herein prescribed. In the event of any conflict, inconsistency, or
other difference between the terms and provisions of the Rules and Regulations,
as now or hereafter in effect and the terms and provisions of any lease nor or
hereafter in effect between Landlord and any tenant in the Building, Landlord
shall have the right to rely on the term or provision in either such lease or
such Rules and Regulations which is most restrictive on such tenant and most
favorable to Landlord.


                                       R-1
                                   Page 3 of 3

<PAGE>   84

                                   RIDER NO. 2

                                EXTENSION OPTIONS

         1. Extension Options. Provided no Event of Default under the Lease
beyond any applicable notice and cure period, either at the time of the exercise
of the options set forth herein or at the time of the commencement of the
extension period hereunder. Tenant may elect to extend the Term of this Lease
("Extension Option(s)") for all or any portion of the Premises for two (2)
additional periods of three (3) years each (collectively, the "Extension
Periods"; individually, the "First Extension Period" and the "Second Extension
Period"), by delivering to Landlord not later than six (6) months before the end
of the initial Term of this Lease or the First Extension Periods"; individually,
the "First Extension Period" and the "Second Extension Period"), by delivering
to landlord not later than six (6) months before the end of the initial Term of
this Lease or the First Extension Period, as applicable, a written notice (the
"Option Notice") of such election. The First Extension Period shall commence on
the day immediately following the last day of the Term and Second Extension
Period shall commence on the day immediately following the last day of the First
Extension Period and shall be subject to all the terms and conditions of this
Lease except that (a) the Rent for the applicable Extension Period shall be
determined in accordance with Section 3 hereinbelow and (b) the Base year for
each Extension period shall be calendar year 2003 for the First Extension Period
and calendar year 2006 for the Second Extension Period.

         2. Options Not Personal. The Extension Options set forth herein are not
personal to Tenant and may be exercised by any assignee of the lease permitted
under the terms of the Lease. However, no such Extension Option is assignable
separate and apart from the Lease.

         3. Base Rent During Extension Periods. The Base Rent for each Extension
period shall be one hundred percent (100%) of the Fair Market Rental Rate (as
hereinafter defined) as of the commencement of the applicable Extension Period.

         4. Fair Market Rental Rate. (a) For the purposes of this Rider No. 2,
the term "Fair Market Rental Rate" shall mean the annual amount per net rentable
square foot that a comparable landlord of a Comparable Building, for comparable
creditworthy tenants, for comparable space, for a comparable use for a
comparable period of time ("Comparable Transaction"). In any determination of
Comparable Transactions appropriate consideration shall be given to the annual
rental rates per net rentable square foot, the type of escalation clause (e.g.,
whether increases in additional rent are determined on a net or gross basis, and
if gross, whether such increases are determined according to a base year or a
base dollar amount expense stop), abatement provisions reflecting, free rent
and/or no rent during the period subsequent to the commencement date as to the
space in question, length of the

                                       R-2
                                   Page 1 of 3
<PAGE>   85

lease term, size and location of premises being leased, and building standard
work letter and/or tenant improvement or refurbishment allowances, if any. The
intent is that Tenant will obtain the same rental and other economic benefits
that landlord would otherwise give in Comparable Transactions and that Landlord
will make, and receive the same economic payments and concessions that Landlord
would otherwise make, and receive in Comparable Transactions.

         Landlord shall determine the Fair Market Rental Rate by using its good
faith judgment. Landlord shall provide written notice of such amount within
thirty (30) days (but in no event later than sixty (60) days) after Tenant
provides the notice to Landlord exercising Tenant's option rights which require
a calculation of the Fair Market Rental Rate. Tenant shall have thirty (30)
days ("Tenant's Review Period") after receipt of landlord's notice of the new
rental within which to accept such rental or to reasonably object thereto in
writing. In the event Tenant objects, Landlord and Tenant shall attempt to
agree upon such Fair Market Rental Rate. If Landlord and Tenant fail to reach
agreement within thirty (30) days following Tenant's Review Period ("Outside
Agreement Date"), then each party shall place in a separate sealed envelope
their final proposal as to Fair Market Rental Rate and such determination shall
be submitted to arbitration in accordance with Section 5 hereinbelow. Failure
of Tenant to so elect in writing within Tenant's Review Period shall
conclusively be deemed its disapproval of the Fair Market Rental Rate
determined by Landlord.

         (b) In the event that Landlord fails to timely generate the initial
written notice of Landlord's opinion of the Fair Market Rental Rate which
triggers the negotiation period of this Section 4, then Tenant may commence such
negotiations by providing, in its good faith judgment, the proposed new rental,
in which even Landlord shall have thirty (30) days ("Landlord's Review Period")
after receipt of Tenant's notice of the new rental within which to accept such
rental. In the event Landlord fails to accept in writing such rental proposed by
Tenant, then such proposal shall be deemed rejected, and Landlord and Tenant
shall attempt to agree upon such Fair Market Rental Rate. If Landlord and Tenant
fail to reach agreement within thirty (30) days following Landlord's Review
Period (which shall be, in such event, the "Outside Agreement Date" in lieu of
the above definition of such date), then each party shall place in separate
sealed envelope their final proposal as to Fair Market Rental Rate and such
determination shall be submitted to arbitration in accordance with Section 5
hereinbelow.

         5. Arbitrator. (a) Landlord and Tenant shall meet with each other
within five (5) business days of the Outside Agreement Date and exchange the
sealed envelopes and then open such envelopes in each other's presence. If
Landlord and Tenant do not mutually agree upon the Fair Market Rental Rate
within one (1) business day of the exchange and opening of envelopes, then,
within ten (10) business days of the exchange and opening of envelopes Landlord
and Tenant shall agree upon and jointly appoint a single arbitrator who shall by
profession be a licensed real estate broker, who shall have been active over the
ten

                                       R-2
                                   Page 2 of 3
<PAGE>   86

(10) year period ending on the date of such appointment in the leasing of
commercial office properties and who has been involve din the leasing of at
least three (3) million square feet or commercial office properties. Neither
Landlord nor Tenant shall consult with such broker as to this or here opinion as
to Fair Market Rental Rate prior to the appointment. The determination of the
arbitrator shall be limited solely to the issue of whether Landlord's or
Tenant's submitted Fair Market Rental Rate for the Premises is the closer to the
actual Fair Market Rental Rate for the Premises as determined by the arbitrator,
taking into account the requirements of Section 4 hereinabove. Such arbitrator
may hold such hearings and require such briefs as the arbitrator, in his or her
sole discretion, determines is necessary. In addition, Landlord or Tenant may
submit to the arbitrator with a copy to the other party within five (5) business
days after the appointment of the arbitrator any market data and additional
information that such party deems relevant to the determination of Fair Market
Rental Rate ("FMRR Data") and the other party may submit a reply in writing
within five (5) business days after receipt of such FMRR Data. Any arbitration
carried out pursuant to this Rider No. 2 shall be governed by the applicable
rules of the American Arbitration Association and the Texas General Arbitration
Act; provided the right to submit testimony and other evidence with respect to
the matter in question, as well as the privilege of cross-examining any
witnesses presented by, or on behalf of the other party

                  (b) The arbitrator shall, within thirty (30) days of his or
her appointment, reach a decision as to whether the parties shall use Landlord's
or Tenant's submitted Fair Market Rental Rate, and shall notify Landlord and
Tenant of such determination.

                  (c) The decision of the arbitrator shall be binding upon
Landlord and Tenant, except as provided below.

                  (d) If Landlord and Tenant fail to agree upon and appoint an
arbitrator, then the appointment of the arbitrator shall be made by the
Presiding Judge of a District Court of Dallas County, Texas, or, if he or she
refuse sot act, by any judge having jurisdiction over the parties.

                  (e) The cost of arbitration shall be paid by Landlord and
Tenant equally. 

         6.       Documentation. Immediately after the Base Rent for the
applicable Extension Period is determined pursuant to this Rider No. 2,,
Landlord and Tenant shall execute an amendment to the Lease stating the new Base
Rent in effect.

         7.       Terms.  All terms used in this Rider No. 2, unless otherwise
defined in this Rider shall have the same meaning as the terms defined in the
Lease.

         8.       Time of the Essence.  Time is of the essence in connection
with this Rider No. 2.

                                       R-2
                                   Page 3 of 3
<PAGE>   87

                                   RIDER NO. 3

                               MUST TAKE EXPANSION

         Tenant shall have the obligation to lease the additional space in the
Building designated below (the "Expansion Space"), upon and subject to the
following terms and conditions:

            Expansion Space                 Delivery Date

            10.056 square feet              One (1) year from the Commence Date
            of Net Rentable Area,
            located on the mezzanine
            level of the Building as more particularly
            set forth on Attachment R-3 hereof

         1. Tenant's right to lease the Expansion Space shall, at Landlord's
option, be of no force or effect if either at the time of the leasing of the
Expansion Space, an Event of Default, with any applicable cure periods having
expired, then exists under any provisions of this Lease.

         2. Tenant may occupy the Expansion Space to Tenant at any time on or
before the Delivery Date, and upon such occupancy the Expansion Space shall
automatically be added to and form a part of the Premises as if originally
demised under this Lease and the terms "Premises" and "Tenant's Share" as
otherwise defined and used in this Lease shall be revise dot include the
Expansion Space. Such leasing of the Expansion Space shall be upon the same
terms and conditions of this Lease, with the Base Rent payable for the Expansion
Space to be the same Base Rent per square foot as set forth in the Lease for the
Premises. The Expansion Space shall be leased to Tenant in its "as is"
condition, except for the representations set forth in Section 2.03 of the
Lease, and Landlord shall make no representation as to such condition nor shall
Landlord have any obligation to decorate, alter, repair, improve or otherwise
prepare the Expansion Space for Tenant's occupancy. Notwithstanding the
foregoing provisions, Tenant shall only pay Operating Costs in connection with
the Expansion Space through the first anniversary of the Commencement Date.
Commencing on the day following the first anniversary of the Commencement Date,
regardless of whether Tenant has occupied the Expansion Space by such date, the
Expansion Space shall become a part of the Premise s and Tenant shall pay Base
Rent and Additional Rent, which Additional Rent shall include Tenant's Share of
Operating Costs in excess of Base Year Operating Costs, for the Expansion Space
in accordance with the lease.

         3. Upon the addition of the Expansion Space to the Premises, Tenant's
Share, as set forth in Section 1.01.K, shall be increased to 100% and Tenant's
Parking Permits, as set forth in Section 1.01.P, shall be increased by
thirty-two (32) parking permits at no charge during the initial Terms.

                                       R-3
                                   Page 1 of 2
<PAGE>   88

         4. Any termination, cancellation or surrender of this Lease shall
terminate Tenant's option for the Expansion Space.

         5. Time shall be of the essence with respect to the exercise by Tenant
of its option under this Rider No. 3.



                                       R-3
                                   Page 2 of 2

<PAGE>   89


                                   RIDER NO. 4
                            RIGHT TO TERMINATE LEASE

         Notwithstanding any provisions or reference to the contrary contained
in the Lease, or any Exhibit or Rider hereto, provided no Event of Default has
occurred and is continuing, Tenant shall have the one time right, at Tenant's
sole option, to terminate this Lease effective on April 30, 2001 ("Termination
Date"), without any liability, except as set forth in this Rider No. 4, provided
that Tenant has provided Landlord written notice by on or before May 1, 2000,
and pays to Landlord, on or before the Termination Date, (a) all unamortized
costs incurred by Landlord in connection with the leasing of the Premises; plus
(b) three (3) months of the then current Base Rent plus Tenant's Operating Costs
Payment (collectively "Termination Payment"). The costs set forth in clause (a)
above shall bear interest at the rate of ten percent (10%) per annum and shall
be amortized over the original Term. Upon the termination of the Lease pursuant
to this Rider No. 4, Tenant shall vacate and return the Premises to Landlord in
"broom clean" condition and otherwise in accordance with the requirements set
forth in the Lease. All Rent under the Lease shall be prorated through the
Termination Date. After the Termination Date, Landlord and Tenant shall have no
further obligations under the Lease as it applies to the lease, except for those
matters which expressly survive the termination of the Lease.

                                       R-4
                                    Solo Page

<PAGE>   90
                                   RIDER NO. 5
                               GENERAL ARBITRATION

         1. Applicability. This Rider No. 5 shall only apply with respect to the
resolution of a dispute pursuant to Section 3.03 of the Lease, Section 5.05 of
the lease, or Section 9.05 of the lease. To institute the provisions of this
Rider No. 5, Tenant shall notify Landlord and in such notice shall designate the
first arbitrator. If the first arbitrator is acceptable to Landlord, Landlord
shall so notify Tenant within ten (10) days after such notice is given and the
first arbitrator shall proceed to determine the matter or dispute within twenty
(20) days thereafter. if the first arbitrator is not acceptable to Landlord,
then within ten (10) days after the giving of Tenant's notice. Landlord shall
designate, in a written notice, the second arbitrator. If Landlord fails to
timely approve the first arbitrator or designate the second arbitrator, then the
first arbitrator shall proceed to determine the matter or dispute within twenty
(20) days after the expiration of such ten (10) day period. If a second
arbitrator is designated, the arbitrators shall meet within ten (10) days after
the designation of the second arbitrator and proceed to jointly appoint a third
arbitrator within ten (10) days after the date the first arbitrator shall be
made within twenty (20) days after his or her appointment. A decision of the
first arbitrator (if a second arbitrator is not designated pursuant to this
Rider No. 5) or the third arbitrator, as applicable, shall be binding and
conclusive on the parties hereto and shall be enforceable as a judgment by the
prevailing party against the losing party. If any arbitrator shall fail, refuse,
or become unable to act, a new arbitrator shall be appointed in his or her place
following the same method as was originally followed with respect to the
arbitrator to be replaced. Landlord and Tenant shall each pay the fees and
expenses of the arbitrator it appoints, but if only one arbitrator is used, or
if a third arbitrator is used, the fees and expenses of such sole or third
arbitrator, as the case may be, as well as the fees and expenses of their
respective counsel shall be borne equally by the parties. All other expenses of
arbitration shall be borne equally by the parties. All hearings and proceedings
held and all investigations and actions taken by the arbitrators shall take
place in Dallas, Texas.

         2. Court Appointment of Arbitrator. Should it be necessary to appoint a
third arbitrator as provided for in paragraph 1 hereinabove and the initial two
(2) arbitrators are unable to agree upon a third arbitrator within ten (10)
days, then either Landlord or Tenant may apply to the appropriate District Court
of Dallas County, Texas for the appointment of the third arbitrator.

         3. Procedures. Any arbitration carried out pursuant to this Agreement
shall be governed by the applicable rules of the American Arbitration
Association and the Texas General Arbitration Act; provided that regardless of
any conflict with any such rules the arbitrators shall afford the parties to
this lease a hearing and the right to submit testimony and other evidence with
respect to the matter in

                                       R-3
                                   Page 1 of 2

<PAGE>   91

question, as well as the privilege of cross-examining any witnesses presented
by, or on behalf of, the other party.

         4. Qualifications of Arbitrators. Any arbitrator appointed by Landlord
or Tenant and any third arbitrator, shall have not less than ten (10) years
experience in connection with the matters at issue in the context of major
suburban office buildings or major mixed-use suburban projects in the Dallas,
Texas metropolitan area. Such arbitrator(s) cannot be affiliated with Landlord
or Tenant to the extent that would cause arbitrators to be a biased party in the
reasonable judgment of the parties. No arbitrator shall have been employed by
either party for the prior three (3) years. Any arbitrator designated to serve
in accordance with the provisions of this Rider No. 5 shall not be affiliated
with any party appointing such arbitrator.

         5. Arbitration Not Relieve Performance. During any arbitration
proceedings pursuant to this Rider No. 5, the parties hereto shall continue to
perform and discharge all of their respective obligations under this lease.

         6. Restriction on Arbitrator's authority. In determining any
controversy or dispute pursuant to Section 3.03, 5.05 and 9.05 of the lease, the
arbitrator shall apply the provisions of the Lease, without departure therefrom
in any respect. The arbitrator shall not have the power to add to, modify or
change any of the provisions of this Lease, but this provision shall not prevent
in any appropriate case the interpretation, construction and determination by
the arbitrator of the applicable provisions of this Lease to the extent
necessary in applying the same to the matters to be determined by arbitration.
The decision of the arbitration shall be accompanied by written findings of fact
as determined in accordance with applicable lease provisions.



                                       R-5
                                    Solo Page

<PAGE>   92
                               COMMENCEMENT NOTICE

         This Commencement Notice is delivered this 7th day of June, 1996, by
Park West E-3 Associates, a joint venture ("Landlord") to NETCOM On-Line
Communications Services, Inc. ("Tenant"), pursuant to the provisions of 3.03 of
that certain Lease Agreement (the "Lease") dated February 23, 1996, by and
between Landlord and Tenant covering space in the Building known as 1607 known
as 107 LBJ Freeway, Dallas, Texas 75234. all terms used herein with their
initial letter capitalized shall have the meaning assigned to such terms in the
Lease.

                                   WITNESSETH:

The Building, the Premises, the Parking Facilities, and all other improvements
required to be constructed and furnished by Landlord in accordance with the
terms of the Lease have been satisfactorily completed by the Landlord and
accepted by the Tenant.

The Premises have been delivered to, and accepted by, the Tenant, subject to the
completion of "punch list" items.

The Commencement Date of the Lease is the 30th day of April, 1996, and the
expiration date is the 30th day of April, 2003.

The Premises consist of 50,771 square feet of Net Rentable Area on the 1st floor
of the Building.

The Base Rent is $292,655.00 per annum, payable in monthly installments of
$24,387.92, subject, however, to the provisions of the Lease relating to
adjustments for Tenant's Operating Costs Payment.

Remittance of the foregoing payments shall be made on the first day of each
month in accordance with the terms and conditions of the Lease at the following
address:

                            Park West E-3 Associates
                      c/o Prentiss Properties Limited, Inc.
                          1717 Main Street, Suite 5000
                               Dallas, Texas 75201

         IN WITNESS WHEREOF, this instrument has been duly executed by Landlord
as of the date first written above.

LANDLORD:

Park West E-3 Associates,
a Texas joint venture
<PAGE>   93

         By:      The Prentiss/Copley Investment Group,
                  a Delaware joint venture

                  By:   Prentiss Property Investments, L.P.
                        a Delaware corporation

                  By:   Prentiss Property Investments, L.P.
                        a Delaware corporation
                     ----------------------------------
                  Name:
                       --------------------------------
                  Title:
                        -------------------------------

                  By:   /s/ J. KEVAN DILBECK
                     ----------------------------------
                  Name:     J. Kevan Dilbeck
                       --------------------------------
                  Title:    Vice President
                        -------------------------------


<PAGE>   94


PACTRUST                                   15350 S.W. Sequoia Pkwy., Suite 300
Pacific Realty Associates, L.P.            Portland, Oregon 97224
                                           503/624-6300 Facsimile: 503/624-7755

February 9, 1999

BY FACSIMILE - 303/414-8869
AND BY U.S. MAIL

Bernard L. Zuroff
Assistant General Counsel
ICG Communications, Inc.
P.O. Box 6742
Englewood, CO 80155-6742

Dear Mr. Zuroff:

Re:      Lease Agreement dated February 23, 1966 (the "LEASE"), between
         NETCOM On-Line Communications Services, Inc., a Delaware
         corporation ("NETCOM") and Park West E-3 Associates ("LANDLORD")

By its signature below, Landlord grants its consent to the assignment by Netcom
of its rights and obligations under the Lease defined above to Mindspring
Enterprises, Inc. ("MINDSPRING"), on the following conditions: (1) the facts
stated in your letter dated February 2, 1999, to Michael Nugent of PacTrust,
including the understanding that Netcom will not realize any "profits" as such
term is defined in Section 8.03 of the Lease from the Assignment, are true and
correct as of the date made and as of the date of the assignment; (2) Netcom and
Mindspring shall execute an assignment and assumption of the lease pursuant to
which, among other things, Mindspring will assume all obligations of Tenant
under the Lease, and Landlord shall be provided with a copy of such assignment
and assumption immediately upon execution thereof; (3) after such assignment and
assumption Mindspring shall be subject to all terms and conditions of the Lease;
and (4) Netcom shall not be released of liability under the Lease
notwithstanding such assignment and assumption.

Landlord's consent granted hereby shall be null and void if Landlord has not
received the assignment and assumption referred to above within thirty (30 days
of the date of this letter. In addition, Landlord's consent granted in this
instance shall not modify the obligation of tenant under the Lease to obtain
Landlord's consent to any future assignment of the Lease.


<PAGE>   95



Please call Mike Nugent or the undersigned if you have any questions. Please be
sure to forward the written Assignment and Assumption Agreement to the
undersigned as soon as possible.

         Very truly yours,

         PARK WEST E-3 ASSOCIATES,
         a Texas joint venture partnership

         By:      PRENTISS/COPLEY INVESTMENT GROUP,
                  a Delaware joint venture, Managing Venturer

                  By:      PAC/SIB L.L.C., a Washington limited
                           liability company, managing Partner

                           By:   PACIFIC REALTY ASSOCIATES, L.P.,
                                 a Delaware limited partnership, Manager Member

                                 By:     PACTRUST REALTY, INC., a Delaware
                                         corporation, General Partner

                                         By: /s/ NANCY B. MURRAY
                                            -----------------------------------
                                         Name:   Nancy B. Murray
                                              ---------------------------------
                                         Its:    AVP/ Associate General Counsel
                                             ----------------------------------


<PAGE>   96


                       ASSIGNMENT AND ASSUMPTION OF LEASE

         THIS ASSIGNMENT AND ASSUMPTION OF LEASE (the "Assignment") is made and
entered into this 8th day of March, 1999 between NETCOM On-Line Communications
Services, Inc., a Delaware corporation ("Assignor"), and Mindspring Enterprises,
Inc., a Delaware corporation ("Assignee").

         In consideration of the promises by Assignee hereunder and other good
and valuable consideration, the receipt and sufficiency of which are hereby
acknowledged by Assignor, Assignor hereby assigns, transfers and conveys to
Assignee, all right, title and interest of Assignor as tenant in and to that
certain lease dated February 23, 1996, as amended, by and between Assignor and
Park West E-3 Associates (the "Lease").

         Assignee hereby expressly assumes all liabilities and agrees to perform
all obligations of Assignor under the Lease to be performed from and after the
date hereof and shall indemnify and hold Assignor harmless from all obligations
on the part of the tenant arising under the Lease from and after the date hereof
and from all liabilities, costs and expenses (including, without limitation,
reasonable attorney's fees) incurred in connection therewith.

         This Assignment shall bind and inure to Assignor and Assignee and their
respective successors and assigns.

                                  NETCOM On-Line Communications Services, Inc.
                                    a Delaware corporation, as Assignor

                                  By:      /s/ DON TEAGUE
                                     --------------------------------------
                                  Name:        Don Teague
                                       ------------------------------------
                                  Title:       Executive Vice President
                                     --------------------------------------

                                  Mindspring Enterprises, Inc., a Delaware
                                  corporation, as Assignee

                                  By:      /s/ SAM DESIMONE
                                     --------------------------------------
                                  Name:        Sam DeSimone
                                       ------------------------------------
                                  Title:       Exec. Vice President
                                        -----------------------------------