<PAGE>   1
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                                                                    EXHIBIT 10.2



                                 LEASE AGREEMENT

                                     BETWEEN



                              CBPBC PHASE VIII, LLC
                        A TEXAS LIMITED LIABILITY COMPANY



                                       AND



                       NUCENTRIX BROADBAND NETWORKS, INC.






                             DATED JANUARY 18, 2001






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<PAGE>   2




                             BASIC LEASE INFORMATION

Lease Date:             January 18, 2001

Tenant:                 NUCENTRIX BROADBAND NETWORKS, INC., a Delaware
                        corporation

Tenant's Address:       4120 International Parkway, Suite 2000
                        Carrollton, Texas 75007

Contact:                Wayne Taylor                   Telephone: 972-633-4064

Landlord:               CBPBC PHASE VIII, LLC, a Texas limited liability company

Landlord's Address:     2200 Ross Avenue, Suite 4800 West
                        Dallas, Texas 75201

Contact:                Mack Dennis                    Telephone: (214) 754-1715


Premises:               Suite No. 2000, in the office building (the "BUILDING")
                        located or to be located on the land described as
                        International Business Park, Carrollton, Denton County,
                        Texas, and whose street address is 4120 International
                        Parkway, Carrollton, Texas 75007, as particularly
                        described in Exhibit A-1 (the "LAND"). The Building and
                        Land together comprise the "PROJECT". The Premises are
                        outlined on the plan attached to the Lease as Exhibit A
                        and shall contain approximately 28,000 square feet of
                        rentable area ("RENTABLE SQUARE FEET" or singularly
                        "RENTABLE SQUARE FOOT"). The Building contains
                        approximately 103,000 of total square feet of rentable
                        area ("TOTAL RENTABLE SQUARE FEET" or singularly "TOTAL
                        RENTABLE SQUARE FOOT"). Within three months after the
                        Commencement Date, the rentable area of the Premises and
                        the Building shall be calculated and confirmed by
                        Landlord's architect, at Landlord's sole cost, utilizing
                        the American National Standard Method for Measuring
                        Floor Area in Office Buildings, ANSI Z65.1 - 1996, as
                        adopted by the Building Owners and Managers Association
                        International (the "BOMA METHOD") and the actual
                        Rentable Square Feet, Total Rentable Square Feet and
                        Tenant's Proportionate Share shall be adjusted as
                        necessary based upon such calculations. Landlord may, in
                        its sole discretion and at its sole cost and expense,
                        following the complete occupancy of the entire rentable
                        area in the Building, re-measure the rentable area of
                        the Premises and the Building using the BOMA Method. In
                        the event of any adjustment to Rentable Square Feet,
                        Total Rentable Square Feet or Tenant's Proportionate
                        Share following the re-measurement referenced in the
                        preceding sentence, Landlord and Tenant shall execute an
                        amendment to the Lease confirming the adjusted Rentable
                        Square Feet, Total Rentable Square Feet, Tenant's
                        Proportionate Share and Rent on a going-forward basis
                        only; specifically, neither Tenant nor Landlord shall be
                        entitled to a credit for any difference in



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                        Rent which would have been paid before the
                        re-measurement as a result of any increase or decrease
                        in the number of Rentable Square Feet or Total Rentable
                        Square Feet.

Term:                   Commencing on the earlier of (a) the date on which
                        Tenant occupies any portion of the Premises and begins
                        conducting business therein or (b) the date on which the
                        Work (as defined in Exhibit D hereto) in the Premises is
                        Substantially Completed (as defined in Exhibit D hereto)
                        (such earlier date is hereinafter referred to as the
                        "COMMENCEMENT DATE"), and ending at 5:00 p.m. on the
                        last day of the 123rd fully calendar month following the
                        Commencement Date, subject to earlier termination and
                        extension as provided in the Lease.

Basic Rental:

<TABLE>
<CAPTION>
                                                       ANNUAL RATE
                                                       PER RENTABLE   BASIC MONTHLY
                    LEASE MONTH                        SQUARE FOOT       RENTAL
         ------------------------------------------    ------------    ----------
<S>                                                    <C>             <C>
                Commencement Date - the 90th
               day after the Commencement Date          $     0.00     $     0.00
          91st day after the Commencement Date - 12     $    21.00     $49,000.00
                           13 - 24                      $    21.50     $50,166.67
                           25 - 60                      $    22.50     $52,500.00
                           61 - 123                     $    25.50     $59,500.00
</TABLE>



                        As used herein, the term "LEASE MONTH" means each
                        calendar month during the Term (and if the Commencement
                        Date does not occur on the first day of a calendar
                        month, the period from the Commencement Date to the
                        first day of the next calendar month shall be included
                        in the first Lease Month for purposes of determining the
                        duration of the Term).

Security Deposit:       $49,000.00 due upon execution of the Lease as referenced
                        in Section 5 of the Lease.

Rent:                   Basic Rental, Tenant's share of Electrical Costs, Excess
                        (if any), and all other sums that Tenant may owe to
                        Landlord under the Lease.

Expense Stop:           The greater of (A) $5.50 per Total Square Foot in the
                        Building, or (B) Basic Cost per Total Square Foot in the
                        Building for the calendar year 2001 (the greater of
                        which is grossed up as provided in Section 4 of Exhibit
                        C of the Lease).



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<PAGE>   4



Permitted Use:          General office use.

Tenant's
Proportionate Share:    27.1845% (which is the percentage obtained by
                        dividing the Rentable Square Feet by the Total Rentable
                        Square Feet; Tenant's Proportionate Share is subject to
                        adjustment upon confirmation of the Rentable Square Feet
                        and Total Rentable Square Feet as provided above).

Construction
Allowance:              $27.00 per Rentable Square Foot in the Premises.

Comparable
Buildings:              As used herein or in the Lease, the term "COMPARABLE
                        BUILDINGS" means other similar size, age, and class
                        office buildings located in the submarket in the area in
                        which the Building is located (i.e., Plano area North of
                        Frankford, East of I-35E, West of Preston Road and South
                        of State Hwy. 121).

The foregoing Basic Lease Information is incorporated into and made a part of
the related lease (the "LEASE"). If any conflict exists between any Basic Lease
Information and the Lease, then the Lease shall control.

LANDLORD:                      CBPBC PHASE VIII, LLC, a Texas limited liability
                               company


                               By: /s/ Mack W. Dennis
                               Name: Mack W. Dennis
                               Title: Manager


TENANT:                        NUCENTRIX BROADBAND NETWORKS, INC.,
                               a Delaware corporation


                               By: /s/ J. David Darnell
                               Name: J. David Darnell
                               Title:  Sr. VP & CFO



                                      iii
<PAGE>   5



                                TABLE OF CONTENTS
<TABLE>
<CAPTION>
                                                                      Page
                                                                      ----
<S>    <C>                                                            <C>
1.     Definitions and Basic Provisions..................................1

2.     Lease Grant.......................................................1

3.     Term..............................................................1

4.     Rent..............................................................2
       (a)         Payment...............................................2
       (b)         Electrical Costs......................................2
       (c)         Annual Electrical Cost Statement......................3
       (d)         Adjustments to Electrical Costs.......................3
       (e)         Delinquent Payment....................................3
       (f)         Taxes.................................................3
       (g)         Excess................................................4
       (h)         Tenant Inspection Right...............................4

5.     Security Deposit..................................................4

6.     Landlord's Obligations............................................4
       (a)         Services; Maintenance.................................4
       (b)         Maintenance...........................................5
       (c)         Excess Electrical Use.................................5
       (d)         Restoration of Services; Abatement....................6
       (e)         Access................................................6

7.     Improvements; Alterations; Repairs; Maintenance...................6
       (a)         Improvements; Alterations.............................6
       (b)         Tenant Repairs; Maintenance...........................8
       (c)         Performance of Work...................................8
       (d)         Mechanic's Liens......................................8

8.     Use...............................................................8

9.     Assignment and Subletting.........................................9
       (a)         Transfers; Consent....................................9
       (b)         Permitted Transfers..................................10
       (c)         Additional Compensation..............................10
       (d)         Cancellation.........................................10

10.    Insurance; Waivers; Subrogation; Indemnity.......................10
       (a)         Insurance............................................10
       (b)         Waiver of Claims; No Subrogation.....................11
</TABLE>



                                       iv
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<TABLE>
<S>    <C>         <C>                                                    <C>
       (c)         Indemnity.................................................11

11.    Subordination; Attornment; Notice to Landlord's Mortgagee.............11
       (a)         Subordination.............................................11
       (b)         Attornment................................................12
       (c)         Notice to Landlord's Mortgagee............................12

12.    Rules and Regulations.................................................12

13.    Condemnation..........................................................12
       (a)         Taking - Landlord's and Tenant's Rights...................12
       (b)         Taking - Landlord's Rights................................13
       (c)         Award.....................................................13

14.    Fire or Other Casualty................................................13
       (a)         Repair Estimate...........................................13
       (b)         Landlord's and Tenant's Rights............................13
       (c)         Landlord's Rights.........................................14
       (d)         Repair Obligation.........................................14

15.    Events of Default.....................................................14

16.    Remedies..............................................................15
       (a)         Landlord's Remedies.......................................15
       (b)         Tenant's Remedies.........................................16

17.    Payment; Non Waiver...................................................16
       (a)         Payment...................................................16
       (b)         No Waiver.................................................16

18.    Landlord's Lien.......................................................17

19.    Surrender of Premises.................................................17

20.    Holding Over..........................................................17

21.    Certain Rights Reserved by Landlord...................................17

22.    Substitution Space....................................................18

23.    Miscellaneous.........................................................18
       (a)         Landlord Transfer.........................................18
       (b)         Landlord's Liability......................................18
       (c)         Force Majeure.............................................18
       (d)         Brokerage.................................................19
       (e)         Estoppel Certificates.....................................19
</TABLE>


                                       v
<PAGE>   7



<TABLE>
<S>    <C>         <C>                                                     <C>
       (f)         Notices...................................................19
       (g)         Separability..............................................19
       (h)         Amendments; and Binding Effect............................19
       (i)         Quiet Enjoyment...........................................19
       (j)         Joint and Several Liability...............................19
       (k)         Captions..................................................20
       (l)         No Merger.................................................20
       (m)         No Offer..................................................20
       (n)         Exhibits..................................................20
       (o)         Entire Agreement..........................................20
       (p)         Representations and Warranties............................20
</TABLE>




                                       vi
<PAGE>   8



                                    EXHIBITS
<TABLE>
<S>                                              <C>
Exhibit A...............................................Outline of the Premises
Exhibit A-1.......................................Legal Description of the Land
Exhibit B........................................Building Rules and Regulations
Exhibit C....................................................Operating Expenses
Exhibit D.........................................Tenant Finish Work: Allowance
Exhibit D-1..................................................Shell Construction
Exhibit E........................................................Renewal Option
Exhibit F...............................................................Parking
Exhibit G.............................................Janitorial Specifications
Exhibit H......................................................Signage Criteria
Exhibit I.....................................................Right to Use Roof
Exhibit J...........................................Preferential Right to Lease
Exhibit K.......Form of Subordination, Non-Disturbance and Attornment Agreement
</TABLE>



                                       vii
<PAGE>   9



                              LIST OF DEFINED TERMS



<TABLE>
<CAPTION>
                                                                       Page
                                                                       ----
<S>                                                                     <C>
Affiliate ................................................................1
Annual Electrical Cost Statement..........................................3
Annual Operating Statement..............................................C-1
Architect ..............................................................D-1
Basic Cost .............................................................C-1
Basic Lease Information...................................................1
BOMA Method ..............................................................i
Building .................................................................i
Building Systems..........................................................5
Casualty ................................................................13
Commencement Date........................................................ii
Comparable Buildings....................................................iii
Completion Termination Date...............................................1
Construction Allowance..................................................D-4
Controllable Expenses...................................................C-4
Damage Notice............................................................13
Disabilities Acts.........................................................7
Electrical Costs..........................................................3
Estimated Delivery Date...................................................1
Event of Default.........................................................14
Excess .................................................................C-1
Excess Period.............................................................1
Force Majeure Delay Day...................................................2
Hard Construction Costs.................................................D-4
Initial Liability Insurance Amount.......................................10
Land .....................................................................i
Landlord .................................................................1
Landlord's Mortgagee.....................................................11
Law ......................................................................1
Laws .....................................................................1
Lease ....................................................................1
Lease Month .............................................................ii
Loss ....................................................................11
Money Rates .............................................................15
Mortgage ................................................................11
Offer Notice............................................................J-1
Parking Area............................................................F-1
Prevailing Rental Rate..................................................E-1
Primary Lease............................................................11
Prime Rate ..............................................................15
Project ..................................................................i
</TABLE>



                                      viii
<PAGE>   10


<TABLE>
<S>                                                             <C>
Refusal Space....................................................J-1
Rentable Square Feet...............................................i
Rentable Square Foot...............................................i
Roof Improvements................................................I-1
Soft Costs ......................................................D-4
Space Plans .....................................................D-1
Space Plans Delivery Deadline....................................D-1
Substantial Completion...........................................D-3
Substantially Completed..........................................D-3
Supplemental Allowance...........................................D-4
Taking ...........................................................12
Taxes ...........................................................C-2
Tenant ............................................................1
Tenant Delay Day.................................................D-3
Third Party Offer................................................J-1
Total Construction Costs.........................................D-4
Total Rentable Square Feet.........................................i
Total Rentable Square Foot.........................................i
Transfer ..........................................................9
Variable Basic Costs.............................................C-4
Work ............................................................D-2
Working Drawings.................................................D-2
Working Drawings Delivery Deadline...............................D-1
</TABLE>



                                       ix



<PAGE>   11



                                 LEASE AGREEMENT


         THIS LEASE AGREEMENT (this "LEASE") is entered into as of January 18,
2001, between CBPBC PHASE VIII, LLC, a Texas limited liability company
("LANDLORD"), and NUCENTRIX BROADBAND NETWORKS, INC., a Delaware corporation
("TENANT").

         1. DEFINITIONS AND BASIC PROVISIONS. The definitions and basic
provisions set forth in the Basic Lease Information (the "BASIC LEASE
INFORMATION") executed by Landlord and Tenant contemporaneously herewith are
incorporated herein by reference for all purposes. To the extent of any conflict
between the Basic Lease Information and any provision contained in this Lease,
this Lease shall control. Additionally, the following terms shall have the
following meanings when used in this Lease: "AFFILIATE" means any person or
entity which, directly or indirectly, through one or more intermediaries,
controls, is controlled by, or is under common control with the party in
question; "LAWS" means all federal, state, and local laws, rules and
regulations, all court orders, governmental directives, and governmental orders,
and all restrictive covenants affecting the Building, and "LAW" shall mean any
of the foregoing.

         2. LEASE GRANT. Subject to the terms of this Lease, Landlord leases to
Tenant, and Tenant leases from Landlord, the Premises.

         3. TERM. The Term shall commence on the Commencement Date and end at
5:00 p.m. on the last day of the 123rd full calendar month following the
Commencement Date, subject to adjustment due to delays caused by Landlord as
provided in Exhibit D or renewal as provided in Exhibit E. Landlord and Tenant
presently anticipate possession of the Premises will be tendered to Tenant (with
the Work to be performed by Landlord therein Substantially Completed) on or
about May 15, 2001 (the "ESTIMATED DELIVERY DATE"). If Landlord is unable to
tender possession of the Premises to Tenant by the Estimated Delivery Date, (a)
Landlord shall not be in default hereunder or liable for damages therefor and
(b) Tenant shall accept possession of the Premises when Landlord tenders
possession thereof to Tenant. Notwithstanding the foregoing, if the Work in the
Premises is not Substantially Completed by the Completion Termination Date (as
defined below), Tenant may terminate this Lease by delivering to Landlord
written notice thereof at any time after the Completion Termination Date, but
before Landlord delivers the Premises with the Work therein Substantially
Completed. As used herein, "COMPLETION TERMINATION DATE" means July 8, 2001,
plus the number of Tenant Delay Days (as defined in Exhibit D) and Force Majeure
Delay Days (as defined below). In the event Landlord fails to deliver the
Premises (with the Work therein Substantially Completed) prior to the Completion
Termination Date and Tenant does not exercise its termination right provided
above, Landlord shall be liable for excess rent and other costs directly caused
by such holdover and actually paid by Tenant with respect to Tenant's current
space for such holdover period beginning on the Completion Termination Date and
ending on the last day of the calendar month in which the Premises are
Substantially Completed (the "EXCESS PERIOD"). Tenant hereby acknowledges that
the hold-over rental rate for Tenant's current space is 138% of the base rental
rate for the last month of Tenant's term. Landlord shall only be liable for
actual amounts paid by Tenant in excess of the base rental rate during the
Excess Period; however, Landlord acknowledges that to the extent Tenant's
current landlord does not allow Tenant to pro-rate Tenant's rent for any partial
month of occupancy during the Excess Period, Landlord shall be liable for all
excess rent actually



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<PAGE>   12



paid by Tenant for the calendar month in which Substantial Completion occurs
(save and except July 2001 which Landlord shall be liable for excess for the
period from the Completion Termination Date until July 31, 2001 if Landlord
delivers Tenant the Premises [with the Work therein Substantially Completed] at
any time in July after the Completion Termination Date). If Landlord has paid to
Tenant any holdover or excess rent pursuant to the preceding sentence, Tenant's
termination right above shall be null and void and of no further effect, unless
Landlord fails to deliver the Premises with the Work Substantially Completed by
October 1, 2001, plus the number of Tenant Delay Days and Force Majeure Delay
Days, following which time Tenant shall have the right to terminate this Lease
upon written notice to Landlord; and following termination by Tenant, Landlord
shall have no further liability for excess rent or costs directly caused by such
holdover and actually paid by Tenant with respect to Tenant's current space. If
Tenant elects to terminate this Lease pursuant to this Section 3, within five
business days of receipt of Tenant's written notice of termination, Landlord
shall return any and all deposits or Rent previously paid by Tenant, as well as
any overage of Total Construction Costs paid to date by Tenant in excess of the
Construction Allowance. By occupying the Premises, Tenant shall be deemed to
have accepted the Premises in their condition as of the date of such occupancy,
subject to Landlord's completion of any related punch-list items. Tenant shall
execute and deliver to Landlord, within ten (10) days after Landlord has
requested same, a letter confirming (1) the Commencement Date, (2) that Tenant
has accepted the Premises, and (3) that Landlord has performed all of its
obligations with respect to the Premises. As used herein, the term "FORCE
MAJEURE DELAY DAY" shall mean each day of delay in obtaining Substantial
Completion caused by events described in Section 23.(c).

         4. RENT.


                  (a) PAYMENT. Tenant shall timely pay to Landlord the Rent
without deduction or set off (except as otherwise expressly provided herein), at
Landlord's Address (or such other address as Landlord may from time to time
designate in writing to Tenant). Basic Rental, adjusted as herein provided,
shall be payable monthly in advance. The first full monthly installment of Basic
Rental (which represents Basic Rental for the fourth Lease Month) shall be
payable contemporaneously with the execution of this Lease; thereafter, monthly
installments of Basic Rental shall be due on the first day of the fifth Lease
Month and each succeeding calendar month during the Term. Basic Rental for any
partial month at the beginning or end of the Term shall be prorated based upon
the number of days within the Term during the partial month multiplied by 1/365
of the then current annual Basic Rental and shall be due on or before the fifth
day immediately preceding the Commencement Date, or first day of the last
calendar month of the Term, as applicable. Notwithstanding the foregoing, in
addition to no Basic Rental obligations for the first three Lease Months of the
Term, all other Rent, including Excess (defined below), shall be fully abated
during the first three Lease Months of the Term.


                  (b) ELECTRICAL COSTS. Tenant may, at Tenant's sole expense,
cause all of its electrical usage in the Premises excluding the common area, to
be submetered at any time during the Term; provided, Tenant gives Landlord 30
days prior written notice of such election, including therewith plans and
specifications of any work to be performed with respect to installing the
necessary submeters and equipment related thereto. Landlord shall not
unreasonably withhold, condition or delay its approval of any plans submitted by
Tenant, unless the work related to installing the submeters or any equipment
related thereto adversely affects the Building's Structure or



                                       2
<PAGE>   13



Building's Systems, and Landlord shall reasonably cooperate with Tenant, at
Tenant's expense, with respect to the installation, maintenance and operation of
any submeters or related equipment. Tenant shall continue to pay Tenant's
Proportionate Share of the common area electrical costs regardless of whether or
not Tenant elects to submeter its electrical usage within the Premises. In the
event Tenant does not elect to separately submeter its electrical usage, Tenant
shall pay to Landlord an amount equal to the product of (1) the cost of all
electricity used by the Project ("ELECTRICAL COSTS"), multiplied by (2) Tenant's
Proportionate Share. Such amount shall be payable monthly based on Landlord's
reasonable estimate of the amount due for each month, and shall be due on the
Commencement Date and on the first day of each calendar month thereafter.
Landlord shall cause any tenants in the Building (or Project) whose equipment
consumes a disproportionate amount of electricity (relative to the other tenants
in the Building or Project) to pay their fair share of Electrical Costs.

                  (c) ANNUAL ELECTRICAL COST STATEMENT. By April 1 of each
calendar year, or as soon thereafter as practicable, Landlord shall furnish to
Tenant a statement of Landlord's actual Electrical Costs (the "ANNUAL ELECTRICAL
COST STATEMENT") for the previous year adjusted as provided in Section 4.(d),
which shall include a reconciliation of the actual amount Tenant owes for its
share of Electrical Costs against the estimated amount collected from Tenant. If
such reconciliation shows that Tenant paid more than owed, then Landlord shall
reimburse Tenant by check or cash for such excess within thirty (30) days after
delivery of the Annual Electrical Cost Statement; conversely, if Tenant paid
less than it owed, then Tenant shall pay Landlord such deficiency within thirty
(30) days after delivery of the Annual Electrical Cost Statement.

                  (d) ADJUSTMENTS TO ELECTRICAL COSTS. If Tenant does not elect
to separately submeter its electrical usage, with respect to any calendar year
or partial calendar year in which the Building is not occupied to the extent of
95% of the rentable area thereof, including the calendar year 2001, the
Electrical Costs for such period shall, for the purposes hereof, be increased to
the amount which would have been incurred had the Building been occupied to the
extent of 95% of the rentable area thereof. In no event shall Landlord be
entitled to recover more than 100% of actual Electrical Costs pursuant to this
Section 4.(d).

                  (e) DELINQUENT PAYMENT. If any payment required by Tenant
under this Lease is not paid when due, Landlord may charge Tenant a fee equal to
5% of the delinquent payment to reimburse Landlord for its cost and
inconvenience incurred as a consequence of Tenant's delinquency. Notwithstanding
the foregoing, Landlord shall waive the late fee referenced in the preceding
sentence one time per twelve month period provided full payment is received by
Landlord within five (5) days of written notice to Tenant. In no event shall the
charges permitted under this Section 4.(e) or elsewhere in this Lease, to the
extent the same are considered to be interest under applicable Law, exceed the
maximum lawful rate of interest.

                  (f) TAXES. Tenant shall be liable for all taxes levied or
assessed against personal property, furniture, or fixtures placed by Tenant in
the Premises. If any taxes for which Tenant is liable are levied or assessed
against Landlord or Landlord's property and Landlord elects to pay the same, or
if the assessed value of Landlord's property is increased by inclusion of such
personal property, furniture or fixtures and Landlord elects to pay the taxes
based on such increase, then



                                       3
<PAGE>   14



Tenant shall pay to Landlord, within ten (10) days of demand, that part of such
taxes for which Tenant is primarily liable.

                  (g) EXCESS. Tenant shall pay the Excess in the Basic Cost over
the Expense Stop as such terms are defined in Exhibit C.

                  (h) TENANT INSPECTION RIGHT. After giving Landlord 30-days'
prior written notice thereof, Tenant may inspect or audit Landlord's records
relating to Annual Operating Statement and the Annual Electrical Cost Statement
for the previous calendar year. If Tenant fails to object to the calculation of
Excess on an Annual Operating Statement or the calculation of Electrical Costs
on the Annual Electrical Cost Statement within 90 days after the statement has
been delivered to Tenant or if Tenant fails to conclude its audit or inspection
within 180 days after the statement has been delivered to Tenant, Tenant shall
have waived its right to object to the calculation of Excess and Electrical
Costs for the year in question and the calculation of Excess and Electrical
Costs set forth on such statements shall be final. Tenant's audit or inspection
shall be conducted only during normal business hours. If the results of the
audit determine that Excess or Electrical Costs are in error 5% in the aggregate
or less for the time period in question, Tenant shall pay the actual cost of
such audit or inspection. If the total Excess or Electrical Costs for the time
period in question is determined to be in error by more than 5% in the
aggregate, Landlord shall pay the actual audit cost, not to exceed $2,500.00 per
audit. Tenant may not conduct an inspection or have an audit performed more than
once during any calendar year. If such inspection or audit reveals that an error
was made in the Excess or Electrical Costs previously charged to Tenant,
Landlord shall refund to Tenant any overpayment of such costs or Tenant shall
pay to Landlord any underpayment of any such costs, as the case may be, within
30 days after notification thereof.

         5. SECURITY DEPOSIT. Contemporaneously with the execution of this Lease
Tenant shall pay to Landlord, in immediately available funds, the Security
Deposit, which shall be held by Landlord without liability for interest and as
security for performance by Tenant of its obligations under this Lease. The
Security Deposit is not an advance payment of Rent or a measure or limit of
Landlord's damages upon an Event of Default (defined below). Landlord may, from
time to time upon notice to Tenant and without prejudice to any other remedy,
use all or a part of the Security Deposit to perform any obligation which Tenant
was obligated, but failed to perform hereunder. Following any such application
of the Security Deposit, Tenant shall pay to Landlord on demand the amount so
applied in order to restore the Security Deposit to its original amount. Within
30 days following the expiration of the Term, as such Term may have been
extended, provided Tenant has performed all of its obligations hereunder,
Landlord shall return to Tenant the balance of the Security Deposit not applied
to satisfy Tenant's obligations in accordance with the terms of this Lease. If
Landlord transfers its interest in the Premises, then Landlord may assign the
Security Deposit to the transferee and, provided Landlord gives Tenant written
notice of such assignment, Landlord thereafter shall have no further liability
for the return of the Security Deposit.

         6. LANDLORD'S OBLIGATIONS.

                  (a) SERVICES; MAINTENANCE. Landlord shall furnish to Tenant
(1) water (hot and cold) at those points of supply provided for general use of
tenants of the Building; (2) heated and refrigerated air conditioning from 7
a.m. to 7 p.m. Monday through Friday and 7 a.m. to 1 p.m. on



                                       4
<PAGE>   15



Saturday (except for holidays) sufficient to maintain temperatures during these
hours in the range of from 70 degrees Fahrenheit to 78 degrees Fahrenheit; (3)
janitorial service to the Premises on weekdays other than holidays (Landlord
reserves the right to bill Tenant separately for extra janitorial service
required for any special improvements installed by or at the request of Tenant)
and such window washing as may from time to time in Landlord's judgement be
reasonably required, such janitorial services to be generally in accordance with
those services described on Exhibit H; (4) non-exclusive elevator for ingress
and egress to the floors on which the Premises are located; (5) replacement of
Building-standard light bulbs and fluorescent tubes, provided that Landlord's
standard charge for such bulbs and tubes, which charge shall be reasonable,
shall be paid by Tenant; and (6) electrical current (subject to Tenant's
obligation to pay its share of Electrical Costs as provided herein). Tenant's
exact HVAC usage and costs will be monitored and added to the Tenant's
proportionate share of other electrical costs. Landlord's obligation to furnish
services under this Section shall be subject to the rules, regulations and other
conditions or requirements of the supplier of such services and any applicable
governmental entity or agency. If Tenant's HVAC is not separately metered and
Tenant desires heat and air conditioning at any time other than times herein
designated, such services shall be supplied to Tenant upon reasonable advance
notice and Tenant shall pay to Landlord the lesser of (1) $40.00 per hour
(minimum 2 hours) for each additional hour (prorated and rounded up to the
nearest quarter hour), or (2) the lowest hourly amount paid by any other tenant
in the Building, such amount being payable within ten (10) days of receipt of an
invoice therefore. Landlord's obligation to furnish services under this Section
shall be subject to the rules, regulations and other conditions or requirements
of the supplier of such services and any applicable governmental entity or
agency.

                  (b) MAINTENANCE. Landlord shall maintain all Shell
Construction items, Building Systems (defined below), and Building common areas
including all parking areas and landscaping, in good order and condition as
customary for Comparable Buildings. "BUILDING SYSTEMS" shall include all
electrical, plumbing, and air conditioning systems within the Building which
either were included in the Shell Construction or which were installed by Tenant
pursuant to this Lease and which meet the following requirements: (i) properly
approved by Landlord; (ii) installed in conformance with all plans and
specifications as approved by Landlord; (iii) Tenant shall have informed
Landlord in writing of the name, address, phone number and contact person of the
contractor responsible for the installation of such system; (iv) Tenant shall
have assigned in writing all contractor's and manufacturer's warranties received
by Tenant in connection with such system; and (v) in connection with Tenant's
contracting for the installation thereof, Landlord shall have been expressly
named as a third party beneficiary to, and shall have been provided copies of,
such contract and any related warranties. Notwithstanding the foregoing,
"BUILDING SYSTEMS" shall not include any improvements made to or within the
Premises which differ from the base building systems or are otherwise
specialized to Tenant's use and occupancy of the Premises and not customary for
office tenants in Comparable Buildings.

                  (c) EXCESS ELECTRICAL USE. Landlord shall use reasonable
efforts to furnish electrical current for computers, electronic data processing
equipment, special lighting, or other equipment that requires more than 120
volts, or other equipment whose electrical energy consumption exceeds normal
office usage, through any existing feeders and risers serving the Building and
the Premises. Tenant shall not install any electrical equipment requiring
special wiring or requiring voltage in excess of 120 volts or otherwise
exceeding Building capacity unless approved



                                       5
<PAGE>   16



in advance by Landlord, which approval shall not be unreasonably withheld,
conditioned or delayed. The use of electricity in the Premises shall not exceed
the capacity of existing feeders and risers to or wiring in the Premises. Any
risers or wiring required to meet Tenant's excess electrical requirements shall,
upon Tenant's request, be installed by Landlord (unless otherwise agreed by
Landlord) at Tenant's expense, if, in Landlord's sole and absolute judgment, the
same are necessary and shall not cause permanent damage or injury to the
Building or the Premises, cause or create a dangerous or hazardous condition,
entail excessive or unreasonable alterations, repairs, or expenses, or interfere
with or disturb other tenants of the Building. If Tenant uses machines or
equipment (other than general office machines, excluding computers and
electronic data processing equipment) in the Premises which affect the
temperature otherwise maintained by the air conditioning system or otherwise
overload any utility, Landlord may install supplemental air conditioning units
or other supplemental equipment (reasonably approved by Tenant) in the Premises,
and the cost thereof, including the cost of installation, operation, use, and
maintenance, shall be paid by Tenant to Landlord within ten (10) days after
Landlord has delivered to Tenant an invoice therefor. At the time of Tenant's
submission of plans and specifications for Landlord's approval pursuant to
Section 7 herein or Exhibit D to this Lease, Landlord and Tenant shall cooperate
in good faith to identify any fixtures, equipment and/or appliances to be
installed or placed in the Premises which fixtures, equipment or appliances
would exceed the normal and customary electrical use and consumption of typical
office tenants in Comparable Buildings, would affect the temperature otherwise
maintained by the air conditioning system, or would require electric capacity in
excess of any planned or existing feeders, risers, or wiring to the Premises.

                  (d) RESTORATION OF SERVICES; ABATEMENT. Landlord shall use
reasonable efforts to restore any service that becomes unavailable; however,
such unavailability shall not render Landlord liable for any damages caused
thereby, be a constructive eviction of Tenant, constitute a breach of any
implied warranty, or, except as provided in the next sentence, entitle Tenant to
any abatement of Tenant's obligations hereunder. However, if Tenant is prevented
from making reasonable use of all or a portion of the Premises for more than
five (5) consecutive business days because of the unavailability of any such
service, Tenant shall, as its exclusive remedy therefor, be entitled to
abatement of Rent, or the pro rata portion thereof equivalent to the portion of
the Premises rendered unusable to the entire Premises, for each consecutive day
(after such five (5) consecutive business day period) that Tenant is so
prevented from making reasonable use of the Premises or the applicable portion
thereof.

                  (e) ACCESS. Subject to any Building rules and regulations,
necessary repairs and maintenance, and any events beyond Landlord's reasonable
control which would prevent access, Tenant shall have access to the Premises
twenty-four (24) hours a day, seven (7) days a week. The Building shall include
twenty-four (24) hour access by security card which cards shall be provided to
Tenant upon payment of a $10 refundable deposit per card.

         7. IMPROVEMENTS; ALTERATIONS; REPAIRS; MAINTENANCE.

                  (a) IMPROVEMENTS; ALTERATIONS. No improvements or alterations
in or upon the Premises, including not by limitation paint, wall coverings,
floor coverings, light fixtures, window treatments, signs, advertising, or
promotional lettering or other media, shall be installed or made by Tenant
except in accordance with plans and specifications which have been previously
submitted



                                       6
<PAGE>   17



to and approved in writing by Landlord, which approval shall not be unreasonably
withheld or delayed except that Landlord may withhold approval of any
improvements or alterations which it determines, in its sole opinion, will
materially and adversely affect any structural or aesthetic (only to the extent
visible from outside the Premises or common areas) aspect of the Building or
Building Systems. Notwithstanding the foregoing, Tenant shall not be required to
obtain Landlord's consent for repainting, recarpeting or other alterations,
tenant improvements, alterations or physical additions to the Premises which are
cosmetic in nature totaling less than $10,000 in any single instance or series
of related alterations performed within a six-month period provided that such
alterations, additions and improvements will not affect (1) the Building's
Structure or the Building's Systems, (2) the provision of services to other
Building tenants, or (3) the appearance of the Building's common areas or the
exterior of the Building; provided that Tenant delivers to Landlord written
notice thereof, a list of contractors and subcontractors to perform the work and
any plans and specifications therefor prior to commencing any such alterations,
additions or improvements (for informational purposes only so long as no consent
is required by Landlord as required by this Lease). All improvements and
alterations (whether temporary or permanent in character) made in or upon the
Premises, either by Landlord or Tenant, shall (A) comply with all applicable
Laws, ordinances, rules and regulations, and (B) be Landlord's property at the
end of the Term and shall remain on the Premises without compensation to Tenant
unless prior to installation, Tenant provides Landlord with written notice of
all items which may be removed by Tenant and Landlord consents to such removal
in advance. Such consent shall not be unreasonably withheld provided Landlord
may condition such consent as it deems reasonably necessary including not by
limitation requiring Tenant to replace any items upon removal with similar items
comparable to any such items in the Building or, if not applicable, then
Comparable Buildings. In connection with Landlord's review and approval (if
required by this Lease) of any of Tenant's proposed alterations, additions or
improvements to the Premises, Landlord may notify Tenant in writing within ten
business days of Tenant's delivery of such notice, or with respect to any work
which requires Landlord's approval, contemporaneously with Landlord's notice of
approval to Tenant with respect to the improvements in question, that Landlord
will require Tenant to remove such alterations prior to the expiration of the
Term; however, if Tenant submits any plans and specifications to Landlord
pursuant to this Section 7.(a) for proposed alterations, additions or
improvements to the Premises and Landlord fails to notify Tenant that Tenant
will be required to remove such alterations, additions or improvements to the
Premises at the expiration of the Term, Landlord may not request such removal at
the expiration of the Term. Approval by Landlord of any of Tenant's drawings and
plans and specifications prepared in connection with any improvements in the
Premises shall not constitute a representation or warranty of Landlord as to the
adequacy or sufficiency of such drawings, plans and specifications, or the
improvements to which they relate, for any use, purpose, or condition, but such
approval shall merely be the consent of Landlord as required hereunder. Landlord
warrants and agrees that it shall complete the Building Shell Construction in
compliance with all then applicable Laws, rules and regulations, including not
by limitation the Americans with Disabilities Acts (defined below).
Notwithstanding anything in this Lease to the contrary, as between Landlord and
Tenant, (i) Tenant shall bear the risk of complying with Title III of the
Americans With Disabilities Act of 1990, any state laws governing handicapped
access or architectural barriers, including the Texas Elimination of
Architectural Barriers Act and all rules, regulations and guidelines promulgated
under such laws, as amended from time to time (the "DISABILITIES ACTS") in the
Premises, and (ii) Landlord shall bear the risk of complying with the
Disabilities Acts in the common areas of the Building and the Project.



                                       7
<PAGE>   18


                  (b) TENANT REPAIRS; MAINTENANCE. Except for those janitorial
services to be provided by Landlord as expressly provided in this Lease, Tenant
shall maintain its personal property and all improvements or alterations to the
Premises other than those items included in Shell Construction (which shall be
maintained by Landlord) in a clean, safe, operable, attractive condition, and
shall not permit or allow to remain any waste or damage to any portion of the
Premises. Tenant shall repair or replace, subject to Landlord's direction and
supervision, any damage to the Project caused by Tenant or Tenant's agents,
contractors, or invitees. If Tenant fails to make such repairs or replacements
within thirty (30) days after written notice of such damage from Landlord,
reasonable wear and tear excepted, then Landlord may make the same at Tenant's
expense, which actual, out-of-pocket expenses shall be payable to Landlord
within ten (10) days after Landlord has delivered to Tenant an invoice therefor.

                  (c) PERFORMANCE OF WORK. All work described in this Section 7
shall be performed only by Landlord or by contractors and subcontractors
approved in writing by Landlord; provided, however, if Landlord fails to notify
Tenant that it approves or disapproves the contractor or subcontractor in
question within ten business days, Landlord shall be deemed to have approved
such contractor or subcontractor. Tenant shall cause all contractors and
subcontractors to procure and maintain insurance coverage against such risks, in
such amounts, and with such companies as Landlord may reasonably require. All
such work shall be performed in accordance with all legal requirements and in a
good and workmanlike manner so as not to damage the Premises, the structure of
the Building, or plumbing, electrical lines, or other utility transmission
facilities or Building mechanical systems. All such work which may affect the
Building's electrical, mechanical, plumbing or other systems must be approved by
the Building's engineer of record.

                  (d) MECHANIC'S LIENS. Tenant shall not permit any mechanic's
liens to be filed against the Project for any work performed, materials
furnished, or obligation incurred by or at the request of Tenant. If such a lien
is filed, then Tenant shall, within thirty (30) days after Landlord has
delivered notice of the filing to Tenant, either pay the amount of the lien or
diligently contest such lien and deliver to Landlord a bond or other security
reasonably satisfactory to Landlord. If Tenant fails to timely take either such
action, then Landlord may pay the lien claim without inquiry as to the validity
thereof, and any amounts so paid, including expenses and interest, shall be paid
by Tenant to Landlord within ten (10) days after Landlord has delivered to
Tenant an invoice therefor.

         8. USE. Tenant shall occupy and use the Premises only for the Permitted
Use and shall comply with all Laws, orders, rules, and regulations relating to
the use, condition, and occupancy of the Premises. The Premises shall not be
used for (i) any use which is disreputable, (ii) creates extraordinary fire
hazards, (iii) results in an increased rate of insurance on the Building or its
contents, or (iv) the storage of any hazardous materials or substances (other
than typical office supplies [e.g., photocopier toner] and other materials used
in the ordinary course of Tenant's business, and then only in compliance with
all Laws). If, because of Tenant's acts, the rate of insurance on the Building
or its contents increases, Tenant shall pay to Landlord the amount of such
increase on demand, and acceptance of such payment shall not constitute a waiver
of any of Landlord's other rights. Tenant shall conduct its business and control
its agents, employees, and invitees in such a manner as not to create any
nuisance or interfere with other tenants or Landlord in its management of the
Project.



                                       8
<PAGE>   19



         9. ASSIGNMENT AND SUBLETTING.

                  (a) TRANSFERS; CONSENT. Other than permitted transfers as
described below, Tenant shall not, without the prior written consent of
Landlord, (1) assign, transfer, or encumber this Lease or any estate or interest
herein whether directly or by operation of law, (2) if Tenant is an entity other
than a corporation whose stock is publicly traded, permit the transfer of an
ownership interest in Tenant so as to result in a change in the current control
of Tenant, (3) sublet any portion of the Premises, (4) grant any license,
concession, or other right of occupancy of any portion of the Premises, or (5)
permit the use of the Premises by any parties other than Tenant (any of the
events listed in Sections 9.(a)(1) through 9.(a)(5) being a "TRANSFER"). If
Tenant requests Landlord's consent to a Transfer, then Tenant shall provide
Landlord with a written description of all terms and conditions of the proposed
Transfer, copies of the proposed documentation, and the following information
about the proposed transferee: name and address; reasonably satisfactory
information about its business; and business history its proposed use of the
Premises. Landlord shall respond in writing to Tenant's request for a Transfer
within ten business days of receipt of written request therefor. If Landlord
fails to notify Tenant that it approves or disapproves the requested Transfer
within ten business days after receipt of Tenant's request and all of the above
referenced information regarding the proposed transferee, Landlord shall be
deemed to have approved such Transfer. Tenant shall reimburse Landlord for its
reasonable attorneys' fees (not to exceed $1,000 per request). Landlord shall
not unreasonably withhold its consent to any assignment or subletting of the
Premises provided the proposed transferee (A) is creditworthy, (B) will use the
Premises for the Permitted Use and will not use the Premises in any manner that
will conflict with any exclusive use agreement or other similar agreement
entered into by Landlord with any other tenant of the Building in existence as
of the date of Tenant's request, (C) is not a governmental entity or subdivision
or agency thereof, (D) is not another occupant in the Building, (E) is not a
person or entity with whom Landlord is then, or has been within the six-month
period prior to the time Tenant seeks to enter into such assignment or
subletting, negotiating to lease space in the Building, and (F) will not exceed
the parking provided in Exhibit F or overload the electrical or other Building
systems; otherwise, Landlord may withhold its consent in its sole discretion. If
Landlord consents to a proposed Transfer, then the proposed transferee shall
deliver to Landlord a written agreement whereby it expressly assumes the
Tenant's obligations hereunder; however, any transferee of less than all of the
space in the Premises shall be liable only for obligations under this Lease that
are properly allocable to the space subject to the Transfer, and only to the
extent of the rent it has agreed to pay Tenant therefor. Landlord's consent to a
Transfer shall not release Tenant from performing its obligations under this
Lease, but rather Tenant and its transferee shall be jointly and severally
liable therefor Landlord's consent to any Transfer shall not waive Landlord's
rights as to any subsequent Transfers. If an Event of Default occurs while the
Premises or any part thereof are subject to a Transfer, then Landlord, in
addition to its other remedies, may collect directly from such transferee all
rents becoming due to Tenant and apply such rents against Rent. Tenant
authorizes its transferees to make payments of rent directly to Landlord upon
Tenant's receipt of notice from Landlord to do so however, Landlord shall not be
obligated to accept separate Rent payments from any transferees and may require
that all Rent be paid directly by Tenant. Notwithstanding the foregoing, prior
to advertising the availability of any space in the Premises for the purpose of
subletting, Tenant shall give Landlord notice of its intent to so advertise the
space, and Landlord shall have the right to consent to the medium of such
advertising only (e.g., the publication or medium in which Tenant wishes to
advertise), which



                                       9
<PAGE>   20



consent shall not be unreasonably withheld, conditioned or delayed. Landlord
shall have no approval or consent rights over the terms contained in such
advertisement.

                  (b) PERMITTED TRANSFERS. Tenant shall be permitted to sublet
portions of the Premises or to assign its rights to any Affiliate of Tenant.
Tenant shall also be permitted to sublet portions of the Premises or to assign
its rights to any organization resulting from a merger or a consolidation with
the Tenant, or any organization succeeding to the business assets of the Tenant,
provided the Premises continue to be used solely for the Permitted Use, the
parking requirements of the subtenant or assignee otherwise complies with all of
the terms of this Lease and the net worth of the subtenant or assignee is at
least $25,000,000 Tenant shall promptly notify Landlord in writing within ten
business days after such assignment or subletting.

                  (c) ADDITIONAL COMPENSATION. Tenant shall pay to Landlord,
immediately upon receipt thereof, fifty percent (50%) of the excess of (1) all
compensation received by Tenant for a Transfer less the costs reasonably
incurred by Tenant with unaffiliated third parties in connection with such
Transfer (i.e., brokerage commissions, marketing costs, tenant finish work, and
the like) over (2) the Rent allocable to the portion of the Premises covered
thereby. Tenant shall hold such amounts in trust for Landlord and pay them to
Landlord within ten (10) days after receipt.

                  (d) CANCELLATION. Landlord may, within twenty (20) days after
submission of Tenant's written request for Landlord's consent to a Transfer
(excluding Permitted Transfers), cancel this Lease (or, as to a subletting or
assignment, cancel as to the portion of the Premises proposed to be sublet or
assigned) as of the date the proposed Transfer was to be effective. If Landlord
cancels this Lease as to any portion of the Premises, then this Lease shall
cease for such portion of the Premises and Tenant shall pay to Landlord all Rent
accrued through the cancellation date relating to the portion of the Premises
covered by the proposed Transfer, all unamortized tenant improvements and
unamortized brokerage commissions (amortized on a straight-line basis over the
initial Term of the Lease) paid or payable by Landlord in connection with this
Lease to the brokerage firms listed in Section 23.(d) that are allocable to such
portion of the Premises. Thereafter, Landlord may lease such portion of the
Premises to the prospective transferee (or to any other person) without
liability to Tenant. In such event, prior to the effective date of such
termination, and subject to Landlord's direction and supervision, Tenant shall
be solely responsible for the cost and construction of a wall demising the
remaining Premises from the portion of the Premises as to which the Lease is
terminated. Notwithstanding the foregoing, if Landlord provides written
notification to Tenant of its election to cancel this Lease as to any portion of
the Premises as provided above, Tenant may rescind its proposed assignment or
subletting of all or any portion of the Premises by notifying Landlord in
writing within five business days following Landlord's written cancellation
notice, and Landlord shall have no further right to cancel this Lease with
respect to that particular request by Tenant, as to that portion of the Premises
to which Tenant has rescinded its notice of subletting or assignment.

         10. INSURANCE; WAIVERS; SUBROGATION; INDEMNITY.

                  (a) INSURANCE. Tenant shall at its expense procure and
maintain throughout the Term the following insurance policies: (1) comprehensive
general liability insurance in amounts of not less than a combined single limit
of $3,000,000 (the "INITIAL LIABILITY INSURANCE AMOUNT") or,



                                       10
<PAGE>   21



following the expiration of the initial Term, such other amounts as Landlord may
from time to time reasonably require, insuring Tenant, Landlord, Landlord's
agents, and their respective Affiliates against all liability for injury to or
death of a person or persons or damage to property arising from the use and
occupancy of the Premises, and (2) insurance covering the full value of Tenant's
property and improvements, and other property (including property of others), in
the Premises. Tenant's insurance shall provide primary coverage to Landlord when
any policy issued to Landlord provides duplicate or similar coverage, and in
such circumstance Landlord's policy will be excess over Tenant's policy. Tenant
shall furnish certificates of such insurance and such other evidence
satisfactory to Landlord of the maintenance of all actual insurance coverage
required hereunder, and Tenant shall obtain a written obligation on the part of
each insurance company to notify Landlord at least thirty (30) days before
cancellation or a material change of any such insurance. All such insurance
policies shall be in form, and be issued by companies, reasonably satisfactory
to Landlord.

                  (b) WAIVER OF CLAIMS; NO SUBROGATION. Landlord shall not be
liable to Tenant or those claiming by, through, or under Tenant for any injury
to or death of any person or persons or the damage to or theft, destruction,
loss, or loss of use of any property or inconvenience (a "LOSS") caused by
casualty, theft, fire, third parties, or any other matter (including Losses
arising through repair or alteration of any part of the Building, or failure to
make repairs, or from any other cause), regardless of whether the negligence of
any party caused such Loss in whole or in part. Landlord and Tenant each waives
any claim it might have against the other for any damage to or theft,
destruction, loss or loss of use of any property, to the extent the same is
insured against under any insurance policy that covers the Building, the
Premises, Landlord's or Tenant's fixtures, personal property, leasehold
improvements, or business, or, in the case of Tenant's waiver, is required to be
insured against under the terms hereof, regardless of whether the negligence or
fault of the other party caused such loss; however, Landlord's waiver shall not
include any deductible amounts on insurance policies carried by Landlord or to
any coinsurance penalty which Landlord may sustain. Each party shall cause its
insurance carrier to endorse all applicable policies waiving the carrier's
rights of recovery under subrogation or otherwise against the other party.

                  (c) INDEMNITY. Each party shall indemnify and hold harmless
the other from and against any and all claims, demands, liabilities, causes of
action, suits, judgements and expenses (including attorneys' fees) arising from
or for injury to third persons or damage to property owned by third persons and
caused by the negligence or intentional torts of the indemnifying party.

         11. SUBORDINATION; ATTORNMENT; NOTICE TO LANDLORD'S MORTGAGEE.

                  (a) SUBORDINATION. This Lease shall be subordinate to any deed
of trust, mortgage, or other security instrument (a "MORTGAGE"), or any ground
lease, master lease, or primary lease (a "PRIMARY LEASE"), that now or hereafter
covers all or any part of the Premises (the mortgagee under any Mortgage or the
lessor under any Primary Lease is referred to herein as "LANDLORD'S MORTGAGEE").
Landlord shall use reasonable efforts to obtain from Landlord's Mortgagee, both
existing and future, and deliver to Tenant a non-disturbance agreement for the
benefit of Tenant in the form attached hereto as Exhibit K or another form
reasonably acceptable to Tenant and Landlord's mortgagee, on or before the
Commencement Date. The subordination of Tenant's rights hereunder to any future
Landlord's Mortgagee under this Section shall be conditioned upon such future
Landlord's Mortgagee's execution and delivery of a Subordination,



                                       11
<PAGE>   22



Non-Disturbance and Attornment Agreement in the form of Exhibit K hereto or
another form reasonably acceptable to Tenant and such Landlord's Mortgagee or
other institutional lenders.

                  (b) ATTORNMENT. Tenant shall attorn to any party succeeding to
Landlord's interest in the Premises, whether by purchase, foreclosure, deed in
lieu of foreclosure, power of sale, termination of lease, or otherwise, upon
such party's request, and shall execute such agreements confirming such
attornment as such party may reasonably request.

                  (c) NOTICE TO LANDLORD'S MORTGAGEE. Tenant shall not seek to
enforce any remedy it may have for any default on the part of the Landlord
without first giving written notice by certified mail, return receipt requested,
specifying the default in reasonable detail, to any Landlord's Mortgagee whose
address has been given to Tenant, and affording such Landlord's Mortgagee a
reasonable period to perform Landlord's obligations hereunder, which period
shall equal the cure period applicable to Landlord hereunder.

         12. RULES AND REGULATIONS. Tenant shall comply with the rules and
regulations of the Building which are attached hereto as Exhibit B. Landlord
may, from time to time, change such rules and regulations for the safety, care,
or cleanliness of the Building and related facilities, provided that such
changes are applicable to all tenants of the Building and will not unreasonably
interfere with Tenant's use of the Premises. Tenant shall be responsible for the
compliance with such rules and regulations by its employees, agents, and
invitees.

         13. CONDEMNATION.

                  (a) TAKING - LANDLORD'S AND TENANT'S RIGHTS. If any part of
the Project (including parking) is taken by right of eminent domain for a period
exceeding ninety (90) days or conveyed in lieu thereof (a "TAKING"), and such
Taking prevents Tenant from conducting its business from the Premises in a
manner reasonably comparable to that conducted immediately before such Taking,
then Landlord may, upon Tenant's written consent, which consent is in Tenant's
sole discretion and shall be deemed denied if not given within ten business days
of Landlord's written election, at Landlord's sole expense, relocate Tenant to
space which is comparable in size (but in no event less Rentable Square Feet),
utility and condition to the Premises within any Comparable Building owned or
under the control of Landlord. Landlord shall notify Tenant of its intention to
do so within thirty (30) days after the Taking. Rent shall be abated on a
reasonable basis as to that portion of the Premises rendered untenantable by the
Taking until relocation. Such relocation may be for a portion of the remaining
Term or the entire Term. Landlord shall complete any such relocation within 120
days after Landlord has notified Tenant of its intention to relocate Tenant. If
Landlord does not elect to relocate Tenant following such Taking or Tenant does
not consent to such relocation, then Tenant may terminate this Lease as of the
date of such Taking by giving written notice to Landlord within sixty (60) days
after the Taking or Landlord's notice of relocation, as applicable, and Rent
shall be apportioned as of the date of such Taking. If Landlord does not
relocate Tenant and Tenant does not terminate this Lease, then Rent shall be
abated on a reasonable basis as to that portion of the Premises rendered
untenantable by the Taking. Upon the occurrence of a Taking, Rent shall be
adjusted on a reasonable basis from the first day of the Taking until such
termination.



                                       12
<PAGE>   23



                  (b) TAKING - LANDLORD'S RIGHTS. If any material portion, but
less than all, of the Project or related parking becomes subject to a Taking, or
if Landlord is required to pay any of the proceeds received for a Taking to
Landlord's Mortgagee, then this Lease, at the option of Landlord, exercised by
written notice to Tenant within thirty (30) days after such Taking, shall
terminate and Rent shall be apportioned as of the date of such Taking. Upon the
occurrence of a Taking, Rent shall be adjusted on a reasonable basis from the
first day of the Taking until such termination.

                  (c) AWARD. If any Taking occurs, then Landlord shall receive
the entire award or other compensation for the Land, the Building and other
improvements taken; however, Tenant may separately pursue a claim (to the extent
it will not reduce Landlord's award) against the condemnor for the value of
Tenant's personal property which Tenant is entitled to remove under this Lease,
moving costs, loss of business and other claims it may have.

         14. FIRE OR OTHER CASUALTY.

                  (a) REPAIR ESTIMATE. If the Premises or the Building are
damaged by fire or other casualty (a "CASUALTY"), Landlord shall, within sixty
(60) days after such Casualty, deliver to Tenant a good faith estimate (the
"DAMAGE NOTICE") of the time needed to repair or replace the damage caused by
such Casualty.

                  (b) LANDLORD'S AND TENANT'S RIGHTS. If a material portion of
the Premises or the Building is damaged by Casualty such that Tenant is
prevented from conducting its business in the Premises in a manner reasonably
comparable to that conducted immediately before such Casualty and Landlord
estimates that the damage caused thereby cannot be repaired within one hundred
fifty (150) days after the date of casualty, then Landlord may, upon Tenant's
written consent, which consent is in Tenant's sole discretion and shall be
deemed denied if not given within ten business days of Landlord's written
election, at Landlord's expense, relocate Tenant to space which is comparable in
size (but in no event less Rentable Square Feet than the Premises), utility and
condition to the Premises within any Comparable Building owned or under the
control of Landlord. Landlord shall notify Tenant of its intention to do so in
the Damage Notice. Rent for the portion of the Premises rendered untenantable by
the damage shall be abated on a reasonable basis from the date of damage until
relocation. Such relocation may be for a portion of the remaining Term or the
entire Term. Landlord shall complete any such relocation within one hundred
twenty (120) days after Landlord has delivered the Damage Notice to Tenant. If
Landlord does not elect to relocate Tenant following such Casualty or Tenant
does not consent to such relocation, Tenant may terminate this Lease by
delivering written notice to Landlord of its election to terminate within thirty
(30) days after the Damage Notice has been delivered to Tenant. If Landlord does
not relocate Tenant and Tenant does not terminate this Lease, then (subject to
Landlord's rights under Section 14.(c)) Landlord shall repair the Building or
the Premises, as the case may be, as provided below. Upon the occurrence of a
Casualty, Rent for the portion of the Premises rendered untenantable by the
damage shall be abated on a reasonable basis from the date of damage until the
completion of the repair or until such termination. Notwithstanding the
forgoing, Tenant shall not be entitled to any abatement of rent or terminate the
Lease if said Casualty is caused by the gross negligence or willful misconduct
of Tenant.



                                       13
<PAGE>   24



                  (c) LANDLORD'S RIGHTS. If (1) a Casualty damages a material
portion of the Building and Landlord makes the good-faith determination to
demolish the remainder of the Building, or (2) if Landlord is required to pay
any insurance proceeds arising out of the Casualty to Landlord's Mortgagee, or
(3) Landlord estimates the damage to the Premises cannot be repair within one
hundred fifty (150) days of the date of the Casualty and if the damage affects
the Premises, Landlord terminates other leases encumbering a material portion of
the Building or, if the damage does not affect the Premises, all other leases in
the Building, then Landlord may terminate this Lease by giving written notice of
its election to terminate within thirty (30) days after the Damage Notice has
been delivered to Tenant, and Rent hereunder shall be abated as of the date of
the Casualty.

                  (d) REPAIR OBLIGATION. If neither party elects to terminate
this Lease following a Casualty, then Landlord shall, within a reasonable time
after such Casualty, commence to repair the Building and the Premises and shall
proceed with reasonable diligence to restore the Building and Premises to
substantially the same condition as they existed immediately before such
Casualty; however, Landlord shall not be required to repair or replace any part
of the furniture, equipment, fixtures, and other improvements which may have
been placed by, or at the request of, Tenant or other occupants in the Building
or the Premises, and Landlord's obligation to repair or restore the Building or
Premises shall be limited to the extent of the insurance proceeds actually
received by Landlord for the Casualty in question.

         15. EVENTS OF DEFAULT. Each of the following occurrences shall
constitute an "EVENT OF DEFAULT" by Tenant:

                  (a) Tenant's failure to pay Rent, or any other sums due from
Tenant to Landlord under the Lease (or any other lease executed by Tenant for
space in the Building), when due, and such failure continues for five (5) days
after written notice thereof is received by Tenant from Landlord; however, if
Landlord has given Tenant such notice during the preceding twelve month period
for failure to timely pay any regularly scheduled installments of Rent (e.g.,
Basic Rental, Tenant's Proportionate Share of Excess and Electrical Costs, and
similar Rent payments), then Landlord's obligation to give written notice with
respect to regularly scheduled installments of Rent shall not apply until twelve
months has passed since the last notice was given, and in the interim, failure
to pay any regularly scheduled installments of Rent on the date due shall be an
Event of Default without Landlord having first given such notice;

                  (b) Tenant's failure to perform, comply with, or observe any
other agreement or obligation of Tenant under this Lease; however, if such
failure cannot be cured within such 30-day period and Tenant commences to cure
such failure within such 30-day period and thereafter diligently pursues such
cure to completion, then such failure shall not be an Event of Default unless it
is not fully cured within an additional 30 days after the expiration of the
initial 30-day period;

                  (c) The filing of a petition by or against Tenant (the term
"TENANT" shall include, for the purpose of this Section 15.(c), any guarantor of
the Tenant's obligations hereunder) (i) in any bankruptcy or other insolvency
proceeding; (ii) seeking any relief under any state or federal debtor relief
law; (iii) for the appointment of a liquidator or receiver for all or
substantially all of Tenant's property or for Tenant's interest in this Lease;
or (iv) for the reorganization or modification of



                                       14
<PAGE>   25



Tenant's capital structure; and provided that in the case of any of the
foregoing which is filed against Tenant, the same is not dismissed within ninety
(90) days after it is filed;

                  (d) The admission by Tenant that it cannot meet its
obligations as they become due or the making by Tenant of an assignment for the
benefit of its creditors; and

                  (e) Tenant abandons all or a substantial portion of the
Premises without giving Landlord ninety (90) days written notice.

         16. REMEDIES.

                  (a) LANDLORD'S REMEDIES. Upon any Event of Default by Tenant,
Landlord may, subject to any judicial process and notice to the extent required
by Title 4, Chapter 24 of the Texas Property Code, as may be amended, in
addition to all other rights and remedies afforded Landlord hereunder or by law
or equity, take any of the following actions:

                           (1) Terminate this Lease by giving Tenant written
         notice thereof, in which event, Tenant shall pay to Landlord the sum of
         (A) all Rent accrued hereunder through the date of termination, (B) all
         amounts due under Section 15.(a), and (C) an amount equal to (i the
         total Rent that Tenant would have been required to pay for the
         remainder of the Term discounted to present value at a per annum rate
         equal to the "PRIME RATE" as published on the date this Lease is
         terminated by The Wall Street Journal, Southwest Edition, in its
         listing of "MONEY RATES", minus (ii) the then present fair rental value
         of the Premises for such period, similarly discounted; or

                           (2) Terminate Tenant's right to possession of the
         Premises without terminating this Lease by giving written notice
         thereof to Tenant, in which event Tenant shall pay to Landlord (A) all
         Rent and other amounts accrued hereunder to the date of termination of
         possession, (B) all amounts due from time to time under Section 15.(a),
         and (C) all Rent and other sums required hereunder to be paid by Tenant
         during the remainder of the Term, diminished by any net sums thereafter
         received by Landlord through reletting the Premises during such period.
         Landlord shall use reasonable efforts to relet the Premises on such
         terms and conditions as Landlord in its sole discretion may determine
         (based on the market conditions then prevailing, including, as
         applicable, a term different from the Term, rental concessions, and
         alterations to, and improvement of, the Premises); however, Landlord
         shall not be obligated to relet the Premises before leasing other
         portions of the Building. Landlord shall not be liable for, nor shall
         Tenant's obligations hereunder be diminished because of, Landlord's
         failure to relet the Premises or to collect rent due for such
         reletting. Tenant shall not be entitled to the excess of any
         consideration obtained by reletting over the Rent due hereunder.
         Re-entry by Landlord in the Premises shall not affect Tenant's
         obligations hereunder for the unexpired Term; rather, Landlord may,
         from time to time, bring action against Tenant to collect amounts due
         by Tenant, without the necessity of Landlord's waiting until the
         expiration of the Term. Unless Landlord delivers written notice to
         Tenant expressly stating that it has elected to terminate this Lease,
         all actions taken by Landlord to exclude or dispossess Tenant of the
         Premises shall be deemed to be taken under this Section 16.(a)(2).



                                       15
<PAGE>   26



         If Landlord elects to proceed under this Section 16.(a)(2), it may at
         any time elect to terminate this Lease under Section 16.(a)(1).

                           (3) Notwithstanding anything to the contrary herein,
         Tenant shall not be deemed to have waived any requirements of Landlord
         to mitigate damages upon an Event of Default as required by Law.

                  (b) TENANT'S REMEDIES.

                           (1) Notice and Cure. If Landlord should fail to
         perform or observe any covenant, term, provision or condition of this
         Lease and such default should continue beyond a period of ten (10) days
         as to a monetary default or thirty (30) days (or such longer period as
         is reasonably necessary to remedy such default, provided Landlord shall
         diligently pursue such remedy until such default is cured) as to a
         non-monetary default, after in each instance written notice thereof is
         given by Tenant to Landlord and Landlord's Mortgagee, then, in any such
         event Tenant shall have the right (but no obligation) to cure the
         default, and Landlord shall reimburse Tenant for all reasonable sums
         expended in so curing said default. Tenant specifically agrees that
         Landlord's Mortgagee may enter the Premises upon reasonable notice to
         Tenant to cure any such default and that the cure of any default by
         Landlord's Mortgagee shall be deemed a cure by Landlord under this
         Lease.

                           (2) Set-off. If Tenant obtains a judgment against
         Landlord or any assignee for any default by Landlord under this Lease
         and (A) Tenant provided Landlord's Mortgagee notice and opportunity to
         cure as described in Section 16.(b)(1) above, (B) said judgment is
         final and all rights of appeal have been exercised or have expired, and
         (C) such judgment remains unsatisfied upon thirty (30) days written
         notice thereof to Landlord's Mortgagee, Tenant may set off such
         judgment against Rent.

         17. PAYMENT; NON WAIVER.


                  (a) PAYMENT. Upon any Event of Default by Tenant, Tenant shall
pay to Landlord all costs incurred by Landlord (including court costs and
reasonable attorney's fees and expenses) in (1) obtaining possession of the
Premises, (2) removing and storing Tenant's or any other occupant's property,
(3) repairing, restoring, altering, remodeling, or otherwise putting the
Premises into condition required by market conditions then prevailing to be
reasonably acceptable to a new tenant, as determined in Landlord's reasonable
discretion, (4) if Tenant is dispossessed of the Premises and this Lease is not
terminated, reletting all or any part of the Premises (including brokerage
commissions, cost of tenant finish work, and other actual out-of-pocket costs
incidental to such reletting), (5) performing Tenant's obligations which Tenant
failed to perform, and (6 enforcing, or advising Landlord of, its rights,
remedies, and recourses arising out of the Event of Default.

                  (b) NO WAIVER. Acceptance or payment of Rent following any
Event of Default shall not waive any rights regarding such Event of Default. No
waiver by any party of any violation or breach of any of the terms contained
herein shall waive any rights regarding any future violation of such term or
violation of any other term.



                                       16
<PAGE>   27



         18. LANDLORD'S LIEN. Landlord hereby waives all contractual, statutory
and constitutional liens held by Landlord on Tenant's personal property, goods,
equipment, inventory, furnishings, chattels, accounts and assets which would
otherwise secure the obligations of Tenant under this Lease.

         19. SURRENDER OF PREMISES. No act by Landlord shall be deemed an
acceptance of a surrender of the Premises, and no agreement to accept a
surrender of the Premises shall be valid unless the same is made in writing and
signed by Landlord. At the expiration or termination of this Lease, subject to
Landlord's obligation to maintain the Building, Tenant shall deliver to Landlord
the Premises with all improvements located thereon in good repair and condition,
reasonable wear and tear (and condemnation and fire or other casualty damage not
caused by Tenant, as to which Sections 13 and 14 shall control) excepted, and
shall deliver to Landlord all keys and/or access cards to the Premises. Provided
that Tenant has performed all of its obligations hereunder, Tenant may remove
all unattached trade fixtures, furniture, and personal property placed in the
Premises by Tenant (but Tenant shall not remove any such item which was paid
for, in whole or in part, by Landlord without Landlord's prior consent). Except
for those alterations, additions or improvements to the Premises for which
Tenant has received a written notice from Landlord (pursuant to Section 7.(a))
requiring Tenant to remove such alterations, additions or improvements at the
expiration of this Lease, Tenant shall not be obligated to remove any
alterations, additions or improvements in the Premises. However, Tenant may, but
shall not be obligated to, remove, at Tenant's expense, such items as Landlord
and Tenant may have agreed upon in writing. Tenant shall repair all damage
caused by removal of any items. All items not so removed shall be deemed to have
been abandoned by Tenant and may be appropriated, sold, stored, destroyed, or
otherwise disposed of by Landlord without notice to Tenant and without any
obligation to account for such items. The provisions of this Section 19 shall
survive the end of the Term.

         20. HOLDING OVER. If Tenant fails to vacate the Premises at the end of
the Term, then Tenant shall be a tenant at will and, in addition to all other
damages and remedies to which Landlord may be entitled for such holding over,
Tenant shall pay, in addition to the other Rent, a daily Basic Rental equal to
the greater of (a) 150% of the daily Basic Rental payable during the last month
of the Term, or (b) the then prevailing market rental rate for leases then being
entered into for similar space in Comparable Buildings.

         21. CERTAIN RIGHTS RESERVED BY LANDLORD. Provided that the exercise of
such rights does not unreasonably interfere with Tenant's Permitted Use or
occupancy of the Premises, and upon reasonable advance notice provided by
Landlord to Tenant (except in case of emergency), Landlord shall have the
following rights:

                  (a) upon reasonable advance notice, to decorate and to make
inspections, repairs, alterations, additions, changes, or improvements, whether
structural or otherwise, in and about the Building, or any part thereof; for
such purposes, to enter upon the Premises and, during the continuance of any
such work, to temporarily close doors, entryways, public space, and corridors in
the Building; to interrupt or temporarily suspend Building services and
facilities (Landlord shall use reasonable efforts to complete any work requiring
the suspension of Building services and facilities during off-business hours
when reasonably and commercially practicable to do so); and to change



                                       17
<PAGE>   28



the arrangement and location of entrances or passageways, doors, and doorways,
corridors, elevators, stairs, restrooms, or other public parts of the Building;

                  (b) to take such reasonable measures as Landlord deems
advisable for the security of the Building and its occupants, including without
limitation searching all items entering or leaving the Building; evacuating the
Building for cause, suspected cause, or for drill purposes; temporarily denying
access to the Building; and closing the Building after normal business hours and
on Saturdays, Sundays, and holidays, subject, however, to Tenant's right to
enter the Building 24 hours a day, seven days a week as provided in Section
6.(e), under such reasonable regulations as Landlord may prescribe from time to
time which may include by way of example, but not of limitation, that persons
entering or leaving the Building, whether or not during normal business hours,
identify themselves to a security officer by registration or otherwise and that
such persons establish their right to enter or leave the Building;

                  (c) to change the name by which the Building is designated,
provided Landlord delivers written notice thereof at least 30 days before such
change; and

                  (d) upon reasonable advance notice, to enter the Premises
during Tenant's regular business hours (or at any time when accompanied by a
representative of Tenant) to show the Premises to prospective purchasers or
lenders, and within the last six months of the Term to show the Premises to
prospective tenants.

         22. SUBSTITUTION SPACE. [Intentionally deleted.]

         23. MISCELLANEOUS.

                  (a) LANDLORD TRANSFER. Landlord may transfer, in whole or in
part, the Project and any of its rights under this Lease. If Landlord assigns
its rights under this Lease and such assignee assumes, in writing, Landlord's
obligations hereunder, then Landlord shall thereby be released from any further
obligations hereunder

                  (b) LANDLORD'S LIABILITY. The liability of Landlord to Tenant
for any default by Landlord under the terms of this Lease shall be limited to
Tenant's actual direct, but not consequential, damages therefor and shall be
recoverable from the interest of Landlord in the Project (including any rents,
profits, or other proceeds therefrom), and Landlord shall not be personally
liable for any deficiency. This section shall not be deemed to limit or deny any
remedies which Tenant may have in the event of default by Landlord hereunder
which do not involve the personal liability of Landlord.

                  (c) FORCE MAJEURE. Other than for Tenant's monetary
obligations under this Lease and obligations which can be cured by the payment
of money (e.g., maintaining insurance), whenever a period of time is herein
prescribed for action to be taken by either party hereto, such party shall not
be liable or responsible for, and there shall be excluded from the computation
for any such period of time, any delays due to strikes, riots, acts of God,
shortages of labor or materials, war, governmental laws, regulations, or
restrictions, or any other causes of any kind whatsoever which are beyond the
control of such party.



                                       18
<PAGE>   29



                  (d) BROKERAGE. Landlord and Tenant each warrant to the other
that it has not dealt with any broker or agent in connection with the
negotiation or execution of this Lease, other than The Staubach Company, whose
commissions shall be paid by Landlord. Tenant and Landlord shall each indemnify
the other against all costs, expenses, attorneys' fees, and other liability for
commissions or other compensation claimed by any broker or agent claiming the
same by, through, or under the indemnifying party.

                  (e) ESTOPPEL CERTIFICATES. From time to time, either Landlord
or Tenant shall furnish, within ten (10) business days after request therefor, a
signed certificate confirming and containing such factual certifications and
representations as to this Lease as the requesting party may reasonably request.

                  (f) NOTICES. All notices and other communications given
pursuant to this Lease shall be in writing and shall be (1) mailed by first
class, United States Mail, postage prepaid, certified, with return receipt
requested, and addressed to the parties hereto at the address specified in the
Basic Lease Information, (2) hand delivered to the intended address, or (3) sent
by prepaid telegram, cable, facsimile transmission, or telex followed by a
confirmatory letter. Notice sent by certified mail, postage prepaid, shall be
effective three business days after being deposited in the United States Mail;
all other notices shall be effective upon delivery to the address of the
addressee. The parties hereto may change their addresses by giving notice
thereof to the other in conformity with this provision.

                  (g) SEPARABILITY. If any clause or provision of this Lease is
illegal, invalid, or unenforceable under present or future laws, then the
remainder of this Lease shall not be affected thereby and in lieu of such clause
or provision, there shall be added as a part of this Lease a clause or provision
as similar in terms to such illegal, invalid, or unenforceable clause or
provision as may be possible and be legal, valid, and enforceable.

                  (h) AMENDMENTS; AND BINDING EFFECT. This Lease may not be
amended except by instrument in writing signed by Landlord and Tenant. No
provision of this Lease shall be deemed to have been waived by Landlord or
Tenant unless such waiver is in writing signed by Landlord or Tenant, and no
custom or practice which may evolve between the parties in the administration of
the terms hereof shall waive or diminish the right of Landlord or Tenant to
insist upon the performance by Landlord or Tenant in strict accordance with the
terms hereof. The terms and conditions contained in this Lease shall inure to
the benefit of and be binding upon the parties hereto, and upon their respective
successors in interest and legal representatives, except as otherwise herein
expressly provided. This Lease is for the sole benefit of Landlord and Tenant,
and, other than Landlord's Mortgagee, no third party shall be deemed a third
party beneficiary hereof.

                  (i) QUIET ENJOYMENT. Provided Tenant has performed all of the
terms and conditions of this Lease to be performed by Tenant, Tenant shall
peaceably and quietly hold and enjoy the Premises for the Term, without
hindrance from Landlord or any party claiming by, through, or under Landlord,
subject to the terms and conditions of this Lease.

                  (j) JOINT AND SEVERAL LIABILITY. If there is more than one
Tenant, then the obligations hereunder imposed upon Tenant shall be joint and
several. If there is a guarantor of



                                       19
<PAGE>   30



Tenant's obligations hereunder, then the obligations hereunder imposed upon
Tenant shall be the joint and several obligations of Tenant and such guarantor,
and Landlord need not first proceed against Tenant before proceeding against
such guarantor nor shall any such guarantor be released from its guaranty for
any reason whatsoever.

                  (k) CAPTIONS. The captions contained in this Lease are for
convenience of reference only, and do not limit or enlarge the terms and
conditions of this Lease.

                  (l) NO MERGER. There shall be no merger of the leasehold
estate hereby created with the fee estate in the Premises or any part thereof if
the same person acquires or holds, directly or indirectly, this Lease or any
interest in this Lease and the fee estate in the leasehold Premises or any
interest in such fee estate.

                  (m) NO OFFER. The submission of this Lease to Tenant shall not
be construed as an offer, nor shall Tenant have any rights under this Lease
unless Landlord executes a copy of this Lease and delivers it to Tenant.

                  (n) EXHIBITS. The following exhibits hereto are incorporated
herein by this reference:

   Exhibit A - Outline of Premises
   Exhibit A-1 - Legal Description of the Land
   Exhibit B - Building Rules and Regulations
   Exhibit C - Operating Expenses
   Exhibit D - Tenant Finish Work: Allowance
   Exhibit D-1 - Shell Construction
   Exhibit E - Renewal Option
   Exhibit F - Parking
   Exhibit G - Janitorial Specifications
   Exhibit H - Signage Criteria
   Exhibit I- Right to Use Roof
   Exhibit J- Right of First Refusal
   Exhibit K - Form of Subordination, Non-Disturbance and Attornment Agreement

                  (o) ENTIRE AGREEMENT. This Lease constitutes the entire
agreement between Landlord and Tenant regarding the subject matter hereof and
supersedes all oral statements and prior writings relating thereto. Except for
those set forth in this Lease, no representations, warranties, or agreements
have been made by Landlord or Tenant to the other with respect to this Lease or
the obligations of Landlord or Tenant in connection therewith.

                  (p) REPRESENTATIONS AND WARRANTIES. Landlord and Tenant each
represent and warrant that the person executing this Lease on its behalf is
acting in his or her capacity as an officer or partner, as applicable, with due
authorization and authority to bind Landlord or Tenant, as applicable, to this
Lease. Landlord represents and warrants that it has good title to the Project so
to fully and properly lease the Premises to Tenant as provided herein. Landlord
represents and warrants that the Project conforms in all material respects to
all applicable Laws, ordinances, rules and



                                       20
<PAGE>   31



regulations generally applicable to commercial office buildings in Carrollton,
Texas, as of the date hereof. Further, Landlord represents and warrants that, to
Landlord's knowledge, the Project contains no hazardous substances as currently
defined under applicable Law, except those used in the operation of the Building
and which are being used in compliance with applicable Law. Other than any
express warranties contained herein, neither Landlord nor Tenant make any
implied warranties of any kind or nature, and the parties hereby waive any
claims upon any such implied warranties.


            [THE REMAINDER OF THIS PAGE IS INTENTIONALLY LEFT BLANK]



                                       21
<PAGE>   32



DATED as of the date first above written.


                                LANDLORD:

                                CBPBC PHASE VIII, LLC, a Texas limited liability
                                company


                                By: /s/ Mack W. Dennis
                                Name: Mack W. Dennis
                                Title: Manager



                                       22
<PAGE>   33



                                TENANT:

                                NUCENTRIX BROADBAND NETWORKS, INC.,
                                a Delaware corporation


                                By: /s/ J. David Darnell
                                Name: J. David Darnell
                                Title: Sr. VP & CFO



                                       23