<PAGE>   1
                                                                   EXHIBIT 10.16


                                   SCHEDULE 1






                                 Office Sublease

                 The Towers At Williams Square -- Central Tower

                                 By and Between

                              TIG Insurance Company

                                       and

                             Advance Paradigm, Inc.

<PAGE>   2

                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                      Page
<S>                                                                                   <C>
INDEX OF DEFINED TERMS..............................................................   vi

1.  Basic Lease Provisions .........................................................    1

2.  Grant and Term .................................................................    3

3.  Minimum Rent ...................................................................    3

4.  Tenant's Electricity Charge ....................................................    3

5.  Operating Costs ................................................................    5

7.  Past Due Obligation ............................................................    6

8.  Commencement of Rent ...........................................................    7

9.  Services by Landlord ...........................................................    7

10. Service Interruptions ..........................................................    8

11. Acceptance of Leased Premises and Building by Tenant ...........................    9

12. Assignment and Subletting ......................................................    9

13. Use and Occupancy ..............................................................   10

14. Alterations and Additions by Tenant ............................................   12

15. Repair and Maintenance by Tenant ...............................................   13

16. Mechanics' Liens ...............................................................   13

17. Limitations on Liability of Landlord; Waiver; Indemnification of Landlord ......   14

18. Tenant's Indemnification of Landlord ...........................................   15

19. Tenant's Insurance .............................................................   15

20. Landlord's Insurance ...........................................................   16

21. Certain Rights Reserved by Landlord ............................................   16
</TABLE>


                                       ii
<PAGE>   3

<TABLE>
<S>                                                                                   <C>
22. Fire or Other Casualty .........................................................   18

23. Condemnation ...................................................................   18

24. Taxes on Tenant's Property .....................................................   19

25. Waiver of Subrogation ..........................................................   19

26. Surrender Upon Termination or Expiration .......................................   19

27. Events of Default ..............................................................   20

28. Landlord's Remedies ............................................................   21

29. No Implied Waiver ..............................................................   23

30. Waiver by Tenant ...............................................................   23

31. Attorneys' Fees and Legal Expenses .............................................   23

32. Subordination ..................................................................   24

33. Quiet Enjoyment ................................................................   24

34. Notice Due to Landlord .........................................................   25

35. Holding Over By Tenant .........................................................   25

36. Rules and Regulations ..........................................................   25

37. Estoppel Certificate ...........................................................   26

38. Notices ........................................................................   26

39. Roof Communication Access and Other Rights .....................................   26

40. Representations and Warranties of Landlord .....................................   27

41. Representations and Warranties of Tenant .......................................   28

42. Hazardous Materials ............................................................   29

43. Business Purpose ...............................................................   29
</TABLE>

                                       iii

<PAGE>   4

<TABLE>
<S>                                                                                   <C>
44. Severability .................................................................    29

45. No Merger ....................................................................    30

46. Force Majeure ................................................................    30

47. Brokerage ....................................................................    30

48. Gender .......................................................................    30

49. Joint and Several Liability ..................................................    30

50. No Representations ...........................................................    31

51. Entire Agreement .............................................................    31

52. Paragraph Headings ...........................................................    31

53. Binding Effect ...............................................................    31

54. Rental Tax ...................................................................    31

55. Parking ......................................................................    31

57. Severability .................................................................    32

58. Disclaimer of Warranties .....................................................    32

59. Work Allowance ...............................................................    33

60. Approvals by Master Landlord .................................................    33

61. Counterparts .................................................................    33

62. Janitor Service ..............................................................    33
</TABLE>


LIST OF EXHIBITS:

EXHIBIT A                 FLOOR PLAN OF LEASED PREMISES

EXHIBIT B                 LEGAL DESCRIPTION


                                       iv
<PAGE>   5

EXHIBIT C                 OPERATING EXPENSE EXCLUSIONS

EXHIBIT D                 SCHEDULE OF JANITORIAL SERVICES

EXHIBIT E                 BUILDING RULES AND REGULATIONS

EXHIBIT F                 FIRST REFUSAL SPACE

EXHIBIT G                 SUBORDINATION, NONDISTURBANCE AND
                          ATTORNMENT AGREEMENT


                                       v
<PAGE>   6

                             INDEX OF DEFINED TERMS

          Except as otherwise provided within this Lease, the Defined Terms set
forth in this Index shall have the meaning ascribed to them in the referenced
pages of the Lease.

<TABLE>
<CAPTION>
                                                                                                       Page
<S>                                                                                                    <C>
Acts ...............................................................................................     1

ADA ................................................................................................    17

Adjusted Gross Rent ................................................................................    13

Affiliate ..........................................................................................    14

Applicable Laws ....................................................................................    15

Base Amount ........................................................................................    13

Base Year ..........................................................................................     6

Basic Lease Provisions .............................................................................     1

BOMA Standards .....................................................................................     3

Broker .............................................................................................    39

Building ...........................................................................................     4

Buildings ..........................................................................................     5

Calendar Year ......................................................................................     8

Commencement Date ..................................................................................     1

Common Areas .......................................................................................     3

Control ............................................................................................    14

Controllable Expenses ..............................................................................     7

Date of this Lease .................................................................................     1

Environmental Requirements .........................................................................    36

Events of Default ..................................................................................    26
</TABLE>

                                       vi

<PAGE>   7

<TABLE>
<S>                                                                                                    <C>
Excess Operating Costs .............................................................................     7

Expiration Date ....................................................................................     4

First Refusal Space ................................................................................    41

Gross Rent .........................................................................................    13

Hazardous Materials ................................................................................    36

Hazardous Substance Survey .........................................................................    37

Improvements .......................................................................................    42

Land ...............................................................................................     4

Landlord ...........................................................................................     1

Landlord's Architect ...............................................................................     3

Lease ..............................................................................................     1

Lease Term .........................................................................................     4

Leased Premises ....................................................................................     4

Major Vertical Penetrations ........................................................................     3

Master Landlord ....................................................................................     1

Master Lease .......................................................................................     1

Master Lease .......................................................................................    35

Master Premises ....................................................................................     1

Minimum Rent .......................................................................................     4

Normal Business Holiday ............................................................................     3

Normal Business Hours ..............................................................................     3

Operating Costs ....................................................................................     7

Plaza ..............................................................................................     5
</TABLE>

                                       vii


<PAGE>   8

<TABLE>
<S>                                                                                                    <C>
Project ............................................................................................     3

Rent ...............................................................................................     9

Rentable Area ......................................................................................     3

Submetered Power ...................................................................................     6

Tenant .............................................................................................     1

Tenant Plans .......................................................................................    43

Tenant's Proportionate Share .......................................................................     7

Total Electricity Costs for the Buildings ..........................................................     6

TREC ...............................................................................................    39

Usable Area ........................................................................................     3

Work Allowance .....................................................................................    43
</TABLE>


                                      viii

<PAGE>   9

                                  OFFICE LEASE


                  (The Towers at Williams Square -- West Tower)

     This Office Sublease (the "Lease") is made and entered into as of 12/16/99
(the "Date of this Lease"), by and between TIG Insurance Company, a California
corporation, (hereinafter called "Landlord"), and Advance Paradigm, Inc., a
Delaware corporation (hereinafter called "Tenant"). The term "Lease" shall mean
this Lease, the Basic Lease Provisions and all Exhibits hereto, as well as all
schedules, exhibits and attachments to any Exhibit to this Lease. Landlord is
the current Tenant under that certain Office Space Lease (the "Master Lease")
dated as of October 4, 1993, by and between T-Las Colinas Towers Corp., a
Delaware corporation, as the landlord, who is predecessor in interest to TIAA
Realty, Inc., a Delaware corporation (the "Master Landlord") and the Landlord as
the tenant, as the same may now or hereinafter be amended, pursuant to which
Master Landlord leased certain premises (the "Master Premises") to Landlord. The
Leased Premises is a part of the Master Premises. This Lease, including without
limitation the rights and privileges of the Tenant hereunder, is expressly made
subject to the terms and conditions of the Master Lease.


[INITIAL STAMP]


     1.   BASIC LEASE PROVISIONS.

     The following provisions set forth various basic terms of this Lease and
are sometimes referred to as the "Basic Lease Provisions".

          (a)  Building Name: The Towers At Williams Square--Central Tower

               Address:       5215 N. O'Connor Blvd., Irving, Texas 75039

          (b)  Floor:         16--Central Tower

               Rentable Area: 24,445 square feet

          (c)  Total Rentable Area of Buildings: 1,344,524 square feet

               Total Rentable Area of the Project: 1,395,980 square feet

          (d)  Annual Minimum Rent: Sixteen Dollars and Twenty-Five Cents
               ($16.25) per square foot of Rentable Area within the Leased
               Premises.

          (e)  Parking: One (1) unreserved space per 300 square feet of Rentable
               Area in the Leased Premises.

          (f)  Commencement Date: March 1,2000

          (g)  Expiration Date: April 30, 2009

                                       1

<PAGE>   10

          (h)  Security Deposit: Waived

          (i)  Tenant's Broker(s): The Staubach Company, a Texas corporation
               Landlord's Broker(s): The Staubach Company, a Texas corporation

          (j)  Permitted Use: General business offices

          (k)  Renewal Options: None

          (l)  Addresses for notices due under this Lease:

               LANDLORD:

               TIG Insurance Company, a California corporation
               5205 N. O'Connor Boulevard
               Suite W559
               Irving, TX 75039
               Attn:   Tom Miller

               TENANT:

               Advance Paradigm, Inc.
               5215 N. O'Connor, Suite 1600
               Irving, TX 75039
               Attn:  General Counsel

          (m) "Rentable Area" of all or any part of each Building (hereinafter
defined) shall mean (1) the Usable Area (hereinafter defined), plus (2) a pro
rata part of the Common Areas (hereinafter defined) within each Building, such
proration based upon the ratio of the Usable Area within such portion of the
Building to the total Usable Area within the applicable Building existing as of
the date of this Lease, including the area encompassed by any columns or other
structural elements which provide support to the Leased Premises and/or the
Buildings, less any Major Vertical Penetrations (hereinafter defined).

          (n) "Project" shall mean the Buildings, the Bank Tower, all associated
parking garages and areas and the Land (hereinafter defined). "Usable Area"
shall mean the square footage of such portion of the Project measured according
to the American National Standard sponsored by the Building Owners and Managers
Association (the "BOMA Standards"). Common Areas" shall mean those areas devoted
to elevator mechanical rooms, corridors, elevator foyers, core area restrooms,
mechanical rooms, janitorial closets, electrical and telephone closets, vending
areas, and lobby areas (whether at ground level or otherwise), and other similar
facilities provided for the common use or benefit of tenants generally and/or
the public. "Major Vertical Penetrations" shall mean the square footage of those
areas within the outside walls used for building stairs, elevator shafts, flues,
vents, stacks, pipe shafts and other vertical penetrations (but shall not
include any such areas for the exclusive use of a particular tenant).

                                        2

<PAGE>   11

          (o) "Normal Business Hours" for the Buildings shall mean 7 a.m. to
6 p.m. Mondays through Fridays, and 7 a.m. to 1 p.m. on Saturdays, exclusive of
Sundays and of any Normal Business Holiday. The term "Normal Business Holiday"
means New Year's Day, Memorial Day, July 4, Labor Day, Thanksgiving and
Christmas.

     2.   GRANT AND TERM.

          Landlord, in consideration of the Rent (hereinafter defined) to be
paid and the covenants and agreements to be performed by Tenant, as hereinafter
set forth, does hereby sublease, demise and let unto Tenant and Tenant accepts
that certain office space, in its current "as is" condition, containing
approximately 24,445 square feet of Rentable Area located in the Building on the
floor shown and designated on the plan attached hereto and made a part hereof as
Exhibit A (said space hereinafter collectively called the "Leased Premises") in
The Towers At Williams Square - Central Tower, 5215 IN. O'Connor Blvd.,Irving,
Texas 75039 (herein called the "Building") located on a certain tract of land
situated in the City of Irving, County of Dallas, State of Texas, more
particularly described in Exhibit B, attached hereto and made a part hereof
(hereinafter called the "Land"), for a term (the "Lease Term") beginning on the
Commencement Date (hereinafter defined), and ending on April 30, 2009 (the
"Expiration Date"), unless sooner terminated as herein provided, upon and
subject to the terms, provisions, covenants, agreements, and conditions of this
Lease as hereinafter stated.

     3.   MINIMUM RENT.

          From and after the Commencement Date, Tenant covenants and agrees to
pay Landlord, without demand and without any setoff or deduction, a base annual
rental of Sixteen Dollars and Twenty-Five Cents ($16.25) per square foot of
Rentable Area in the Leased Premises, (hereinafter called the "Minimum Rent"),
in equal monthly installments in advance on the first day of each calendar month
during the Lease Term.

     4.   TENANT'S ELECTRICITY CHARGE.

          Landlord, subject to payment by Tenant as set forth below, shall
furnish sufficient power for lighting (at 277 volts) and for typewriters, voice
writers, calculating machines, personal computers, copiers, facsimile machines,
and other standard office machines of similar low electrical consumption, but
not including electricity for equipment or machines that require a nominal
voltage of more than 120 volts single phase. Tenant shall give Landlord written
notice prior to placing any such equipment or machines requiring more than 120
volts single phase in the Leased Premises. If Tenant's requirements for
electricity or special lighting are in excess of those set forth in the
preceding sentences, Tenant shall give Landlord written notice of Tenant's
requirements, and Landlord, at Tenant's expense to be reimbursed to Landlord as
additional Rent upon demand, to the extent feasible will supply such service
through the then existing feeders servicing the Buildings and will bill Tenant
for its excess electricity requirements as set forth below. If Tenant has any
equipment or machines or special lighting that require excess amounts of
electricity, Landlord reserves the right, at its sole option, except as provided
hereinafter, to


                                       3
<PAGE>   12

install a separate submeter(s), at Tenant's expense to be reimbursed to Landlord
as additional Rent upon demand, for the Leased Premises or any part or parts
thereof. If Tenant has excess electricity requirements for which Landlord does
not elect to install separate submeter(s), Landlord's engineer shall determine
the amount of excess electricity to be allocated to Tenant based on the power
requirements of any such equipment, machines, or special lighting. If Tenant
does not agree with the amount of such allocation, Tenant may require Landlord
to exercise Landlord's option to install separate submeter(s) by giving written
notice to Landlord. Landlord shall not be liable to Tenant for any failure or
defect in the supply or character of electric energy furnished to the Leased
Premises due solely to any requirement, act, or omission of the public utility
serving the Buildings with electricity. Whenever heat-generating machines or
equipment (other than such standard office machines) or special lighting which
affect the temperatures otherwise maintained by the air conditioning system, are
used in the Leased Premises by Tenant, Landlord shall have the right to install
supplemental air conditioning units in the Leased Premises, and the cost
thereof, including the cost of installation, operation, use and maintenance,
shall be paid as additional Rent by Tenant to Landlord on demand. The obligation
of Landlord to furnish electrical service shall be subject to the rules and
regulations of the supplier of such electricity and of any municipal or other
governmental authority regulating the business of providing electrical utility
service. Tenant covenants and agrees that at all times its use of electric
current shall be consistent with the capacity of existing feeders to the
Buildings, or the risers or wiring installations, all as constructed, installed
or modified pursuant to this Lease. Any riser or risers or wiring to meet
Tenant's excess electrical requirements will be installed by Landlord upon
written request of Tenant, at the sole cost and expense of Tenant to be
reimbursed to Landlord as additional Rent upon demand, if, in Landlord's sole
judgment, the same are necessary and will not cause permanent damage or injury
to the Buildings or the Leased Premises or cause or create a dangerous or
hazardous condition or entail excessive or unreasonable alterations, repairs or
expense or interfere with or disturb other tenants or occupants.

          Tenant covenants and agrees to pay to Landlord as additional Rent,
without any set-off or deduction, Tenant's pro rata share of all electricity
consumed in the use, occupancy, and operation of the Buildings and all related
improvements and appurtenances, which related improvements and appurtenances
include the perimeter lights associated with the Building, the East Tower, the
Central Tower, or the Bank Tower (collectively, the "Buildings") and the Plaza
(the "Plaza" being the area paved with granite and surrounding the equestrian
sculpture) and the exterior perimeter lights for the remainder of the Towers at
Williams Square. Tenant's pro rata share for all electricity used in the
Buildings and related improvements and appurtenances including electricity used
for heating and air conditioning shall be determined by multiplying the Total
Electricity Costs for the Buildings (hereinafter defined) net of Tenant
Submetered Power (hereinafter defined) and after-hours utility charges as
aforesaid by a fraction, the numerator of which is the square footage of the
Rentable Area in the Leased Premises and the denominator of which is the square
footage of Rentable Area in the Buildings. The term "Total Electricity Costs for
the Buildings" shall mean the total electric cost charged to Master Landlord by
the local electric utility service, including taxes, for the Buildings, but may
not include any administrative fee or charge by Master Landlord. The term
"Submetered Power" shall mean all supplemental tenant electrical power which is
separately submetered by Landlord or Master Landlord or which is separately
tracked and calculated by Landlord's or Master Landlord's engineer for tenants
in the Building, including Tenant.

                                       4
<PAGE>   13

          In addition to the above, Tenant shall pay to Landlord Tenant's direct
cost of separately submetered electricity costs as determined by Landlord or
Master Landlord and its after hour electricity charges.

          Notwithstanding anything to the contrary herein before contained,
Landlord may at any time during the Lease Term, elect to install submeters
measuring electricity used in the Buildings and/or the Leased Premises which may
also include submeters measuring electricity used for heating and cooling the
Buildings and/or Leased Premises and in such cases, Tenant's pro rata share of
such costs shall then be based on actual use as measured by such submeters but
with any areas sharing a submeter being prorated on the basis that the area of
the Leased Premises bears to the area covered by the submeters.

          Landlord shall bill Tenant for Tenant's electricity charge monthly
throughout the Lease Term and Tenant shall pay same within three (3) business
days after receipt of each such bill. Landlord shall bill Tenant for Tenant's
electricity charge for the last month or portion thereof of the Lease Term as
soon as practicable after the termination or expiration of this Lease and Tenant
shall pay same within three (3) business days after receipt of such bill; the
Tenant's obligation to pay such billing shall survive the termination or
expiration of the Lease. All payments for Tenant's electricity charge are to be
predicated upon separate and specific bills by Landlord and are not to be
included as part of the Minimum Rent payment required to be paid pursuant to
Paragraph 3 hereof. Any such payment shall, however, be deemed as Rent payable
hereunder.

     5.   OPERATING COSTS.

          Tenant hereby agrees to pay to Landlord Tenant's Proportionate Share
(as hereinafter determined) of any increase in all Operating Costs (hereinafter
defined) during the term of this Lease which exceeds $8.50 per square foot of
Rentable Area during years 2000 through 2004 inclusive, and which exceeds $10.50
per square foot of Rentable Area during years 2005 through the end of the Lease
Term, as determined by Landlord ("Excess Operating Costs"). "Tenant's
Proportionate Share" of Excess Operating Costs shall be determined by
multiplying such excess by a fraction, the numerator of which is the number of
square feet of Rentable Area in the Leased Premises and the denominator of which
is the number of square feet of Rentable Area in the Project. If for any time
period in question the number of square feet occupied in the Project is less
than 95%, those elements of Operating Costs that vary based on the occupancy
rate of the Project shall be extrapolated (increased) by Landlord as though the
Project was 95% occupied and if such information is furnished to Landlord by
Master Landlord, the annual statement for that period will show the elements
that were extrapolated.

          Except as otherwise provided for in and subject to the limitations of
Exhibit C to this Lease, the term "Operating Costs" as used herein shall mean
those expenses (other than expenses for electricity) directly incurred in the
management, operation, maintenance, repair and security of the Buildings,
including but not limited to the cost of all utilities, building supplies,
janitorial service, maintenance and repairs, fire and extended coverage, public
liability and other


                                       5
<PAGE>   14

insurance, all labor and employee benefit costs (including wages, salaries and
fees of all personnel engaged in the management, operation, maintenance, repair
and security of the Project), ad valorem taxes and assessments, costs which
reduce operating expenses or are required to meet governmental regulations,
management fees, consulting fees, legal fees and accounting fees, and the fair
market rental of the property managers' offices in the Project, together with
payments or credits Landlord may make to any tenant or tenants of the Project in
lieu of Landlord providing any of the services or paying for any of such costs.

          On or prior to the Commencement Date and on or before the fifteenth
day of each December thereafter during the Lease Term, Landlord shall provide
Tenant with Landlord's reasonable estimate of Tenant's Proportionate Share of
the Excess Operating Costs for the forthcoming calendar year, as determined by
Landlord. In addition to Tenant's obligation to pay Minimum Rent, Tenant shall
pay to Landlord monthly in advance on or before the first day of each calendar
month during the term hereof, one twelfth, (1/12th) of Tenant's Proportionate
Share of such Excess Operating Costs for the applicable calendar year. For the
purposes hereof, the term "calendar year" shall also include partial calendar
years.

          Within 190 days after the expiration of calendar year 2000 and each
subsequent calendar year thereafter during the Lease Term, Landlord shall
furnish Tenant with a statement certified by a duly authorized representative of
Landlord setting out in reasonable detail the actual Excess Operating Costs for
the Project for the prior calendar year. In the event the sum of the payments
made by Tenant during the preceding calendar year or partial calendar year
pursuant to the foregoing exceeds the amount which Tenant would have been
obligated to pay if the actual Excess operating Costs for such year were used in
lieu of Landlord's estimate thereof, the difference shall be credited by
Landlord to Tenant's account against the next payments due by Tenant under the
provisions hereof. In the event the sum of payments made by Tenant during the
preceding calendar year or partial calendar year pursuant to the above paragraph
is less than the amount which Tenant would have been obligated to pay if the
actual Excess Operating Costs for such year or partial year were used in lieu of
Landlord's estimate thereof, Tenant shall pay the amount of such difference to
Landlord in cash within twenty (20) days after delivery of any invoice therefor
by Landlord accompanied by a statement of the actual Excess Operating Costs for
such year.

     6.   DEFINITION OF RENT.

          As used in this Lease, "Rent" shall mean the Minimum Rent and all
other amounts provided for in this Lease to be paid by Tenant to Landlord, all
of which shall constitute rental in consideration for this Lease and the
subleasing of the Leased Premises. The Rent shall be paid at the times and in
the amounts provided for herein in legal tender of the United States of America
to Landlord at the address specified above or to such other person or at such
other address as Landlord may from time to time designate in writing. Except for
Rent which is abated pursuant to the terms hereof, the Rent shall be paid
without notice, demand, abatement, deduction or offset.

     7.   PAST DUE OBLIGATION.

          Except for Rent which is abated pursuant to the terms hereof, all
installments of Rent and

                                       6
<PAGE>   15

any other sums due and payable by Tenant to Landlord or any sums due and payable
by Landlord to Tenant not paid within 10 days after they become due and payable
shall bear interest at rate of 18% per annum from the date due.

     8.   COMMENCEMENT OF RENT.

          This Lease and the obligations of Tenant shall commence on the
Commencement Date and continue in full force and effect until the expiration of
the Lease Term. Tenant shall be allowed access to the Leased Premises for the
purpose of construction of Tenant's improvements pursuant to Paragraph 61
without commencement of Rent. Rent shall commence on the later of: upon
substantial completion of Tenant Improvements or upon occupancy or March 1,
2000.


[INITIAL STAMP]


     9.   SERVICES BY LANDLORD.

          To the extent furnished by the Master Landlord to Landlord under the
Master Lease, Landlord agrees to furnish to the Leased Premises the following:

          (a) air conditioning, both heating and cooling (as required by the
seasons); during Normal Business Hours at a temperature ranging plus or minus 2
degrees from: in summer, 76 degrees Fahrenheit dry bulb maximum indoor building
temperature with a 50% maximum relative humidity based on a design outdoor
temperature of 102 degrees Fahrenheit dry bulb, 78 degrees Fahrenheit wet bulb
and using a 1% design column; and in winter, 72 degrees Fahrenheit dry bulb
minimum indoor building temperature based on a design outdoor temperature of 18
degrees Fahrenheit dry bulb and using a 99% design column; provided, however,
that circulating air will not be available other than by air conditioning and if
Tenant shall require air conditioning at any time other than during Normal
Business Hours, Landlord shall furnish the same for the area or areas specified
in a written request of Tenant delivered to the Landlord and the superintendent
of the Project before 3:00 p.m. of the business day preceding this extra usage,
and for such service Tenant shall pay Landlord, as additional Rent within five
(5) days after receipt of a bill therefor, the actual cost of such service as
reasonably determined by Master Landlord's engineer for the Buildings and if
more than one tenant has requested and is furnished this service for the same
hour(s), it is understood that the charge will be prorated if such proration is
reasonably possible and practicable;

          (b) cold water (at the normal temperature of the supply of water to
the Project) for lavatory and toilet purposes, refrigerated water for drinking
purposes at the core area fountains, and hot water at a temperature ranging
between 100 degrees and 120 degrees Fahrenheit (from the regular Project supply
at prevailing temperatures) for core area restroom lavatory purposes, all of
such water service to be supplied from the regular supply of water to the
Buildings at points of supply provided for general use of tenants of the
Buildings;

          (c) janitor and maid service to the Leased Premises on days other than
Fridays, Saturdays, and Normal Business Holidays in accordance with the cleaning
schedule attached hereto as Exhibit D and exterior, perimeter window washing at
least semiannually and more often, if necessary in the reasonable judgment of
the Master Landlord;


                                       7
<PAGE>   16

          (d) operator-less passenger elevators where applicable and provided
for ingress and egress from the floor(s) on which the Leased Premises are
located, provided that Master Landlord may reasonably limit the number of
elevators to be in operation on Saturdays, Sundays and Normal Business Holidays,
and freight elevator service in common with other tenants but only when
scheduled through the managers of the Buildings;

          (e) Building standard core area rest room facilities;

          (f) electric lighting for all public areas and special service areas
of the Buildings in the manner and to the extent deemed by Master Landlord to be
Building Standard including replacement of Building Standard light bulbs and
tubes;

          (g) All replacement lighting tubes (F34WW fluorescent Wattmiser) and
bulbs (11 watt fluorescent flood light) for elevator lobbies required in
Building Standard fixtures in the Leased Premises will be furnished and
installed by Landlord at Landlord's expense.

          (h) Building standard smoke detection and alarm systems for the
Buildings and all substitutions, additions and replacements of such systems; and

          (i) Building standard security to the Leased Premises, the Project,
the Plaza and all parking facilities, which security may include limited access
entry cards to the Buildings or parking facilities and security personnel in
stationary locations or in mobile patrols.

Landlord hereby assigns to Tenant all of Landlord's rights under Paragraph 10 of
the Master Lease to the extent necessary to require Master Landlord to furnish
the above services to Tenant.

     10.  SERVICE INTERRUPTIONS.

          Landlord does not warrant that the services provided for in Paragraph
10 above will be free from any slow-down, interruption, or stoppage caused by
the maintenance, repair, substitution, renewal, replacement, or improvement of
any of the equipment involved in the furnishing of any such services or caused
by changes of services, alterations, strikes, lock-outs, labor controversies,
fuel shortages, accidents, acts of God, the elements, or any other cause beyond
the reasonable control of Landlord or Master Landlord, and specifically no such
slow-down, interruption, or stoppage of any such services shall ever be
construed as an eviction, actual or constructive, of Tenant nor, except as
otherwise provided below, shall same cause any abatement of the Rent payable
hereunder or in any manner or for any purpose relieve Tenant from any of its
obligations hereunder, and in no event shall Landlord or Master Landlord be
liable for damage to persons or property, or in default hereunder, as a result
of such slow-down, interruption, or stoppage. Landlord shall not be liable for
any failure by Master Landlord to provide utilities or services to the Leased
Premises. If (a) any service required to be provided by Master Landlord under
Paragraph 10 is continuously interrupted due solely to causes within the
exclusive control of Landlord or Master Landlord, (b) Tenant provides Landlord
notice specifying the interrupted service(s) within 48 hours after the
interruption commences, (c) the interruption continues for 5 business days after
the date Landlord receives Tenant's notice, and (d) the Leased Premises are not
reasonably usable by Tenant solely to the interruption, then, as

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<PAGE>   17

Tenant's sole and exclusive remedy for the interruption, the Minimum Rent abates
starting on the 6th business day after the date Landlord receives Tenant's
notice and continuing through the day before the date the services are restored.

     11.  ACCEPTANCE OF LEASED PREMISES AND BUILDING BY TENANT.

          With the exception of latent defects, including structural defects,
the taking of possession of the Leased Premises by Tenant shall be conclusive
evidence that Tenant: (i) accepts the Leased Premises as suitable for the
purposes for which same are leased; and (ii) accepts the Leased Premises, the
Building, the Land, and all related improvements and appurtenances and each and
every part thereof as being in a good and satisfactory condition. Landlord shall
not be liable, except in the event of gross negligence or willful misconduct, to
Tenant or any of its agents, employees, licensees, servants, or invitees for any
injury or damage to person or property due to the condition or design of, or any
defect in, the Building or related improvements or their mechanical systems and
equipment that may exist or occur, and Tenant, with respect to itself and its
agents, employees, licensees, servants, and invitees hereby expressly assumes
all risks of injury or damage to person or property, either proximate or remote,
by reason of the condition or design of, or any defects in, the Leased Premises
or the Building or the Land, or the related improvements or appurtenances.

     12.  ASSIGNMENT AND SUBLETTING.

          (a) Tenant may not sell, assign, transfer or hypothecate this Lease or
any interest herein (either voluntarily or by operation of law) or sublet the
Leased Premises or any part thereof without the prior written consent of
Landlord which shall not be unreasonably withheld, except as hereinafter
provided. If Tenant should desire to assign this Lease or sublet the Leased
Premises (or any part thereof), Tenant shall give Landlord written notice at
least thirty (30) days in advance of the date on which Tenant desires to make
such assignment or sublease. Except with respect to an assignment or subletting
permitted by subparagraph (c) of this Paragraph 13, Landlord shall then have a
period of thirty (30) days following receipt of such notice within which to
notify Tenant in writing that Landlord elects either (i) to terminate this Lease
as to the space so affected as of the date specified by Tenant in its notice, in
which event Tenant, subject to the provisions of this Lease which expressly
survive the termination hereof, shall be relieved of all further obligations
hereunder as to such space; (ii) to permit Tenant to assign or sublet such
space, subject, however, to the subsequent written approval of the proposed
assignee or subtenant by Landlord; provided, however, that if the rental rate
agreed upon between Tenant and its proposed subtenant under any proposed
sublease of the Leased Premises (or any part thereof) is greater than the rental
rate that Tenant must pay Landlord hereunder for that portion of the Leased
Premises that is subject to such proposed sublease, or if any additional
consideration shall be received by Tenant in connection with such proposed
assignment or sublease (in addition to rental as provided in such proposed
sublease), then such additional consideration, or, with respect to any excess
rents, the Adjusted Gross Rent (hereinafter defined) as the case may be (or
both) shall be retained by Tenant, or (iii) to reasonably refuse, in accordance
with the provision set forth above in this subparagraph 13(a), to consent to
Tenant's assignment or subleasing of such space and to continue this Lease in
full force and effect as to the entire Leased Premises. If Landlord should fail
to notify Tenant in writing of such election

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<PAGE>   18

within such thirty (30) day period, Landlord shall be deemed to have elected
option (ii) above. No assignment or subletting by Tenant under this Paragraph 13
shall relieve Tenant of Tenant's obligations under this Lease. Any attempted
assignment or sublease by Tenant in violation of the terms and provisions of
this Paragraph 13 shall be void. The term "Adjusted Gross Rent" shall mean the
Gross Rent less the Base Amount. "Gross Rent" shall mean the minimum or base
rent specified in the sublease. The "Base Amount" shall mean $16.25 per square
foot.

          (b) For purposes of this Paragraph 13, if neither Advance Paradigm,
Inc. nor any of its Affiliates is the Tenant hereunder and Tenant is a
corporation, partnership, or other entity rather than a natural person, any
transfer, whether in a single transaction or in a series of transactions
(related or unrelated) of the controlling interest in such entity shall
constitute an assignment of this lease. Notwithstanding any provision or
agreement to the contrary, in no event shall the transfer of all or
substantially all of the stock or assets of Tenant or any of its successors or
assigns that becomes a tenant through merger, acquisition or any other business
combination constitute an assignment or sublease under this Lease or require the
consent of Landlord hereunder.

          (c) Tenant may, without the prior written consent of Landlord, sublet
the Leased Premises or any part thereof to an Affiliate (hereinafter defined),
or assign this Lease to an Affiliate or permit occupancy of any portion of the
Leased Premises by an Affiliate. The term "Affiliate" shall mean (i) any
corporation which, directly or indirectly, Controls (hereinafter defined) or is
Controlled by, or is under common control with Tenant or (ii) any corporation
not less than fifty percent (50%) of whose outstanding stock shall, at the time
be owned directly or indirectly by Tenant or Tenant's parent corporation. For
purposes of this subparagraph 13(c), "Control" shall mean the possession,
directly or indirectly, of the power to direct or cause the direction of the
management and policies of such corporation, whether through the ownership of
voting securities or by contract or otherwise.

          (d) At any time after the Commencement Date Landlord shall have the
right to transfer assign, convey or sublet, in whole or in part, the Leased
Premises and any and all of its rights under this Lease, and in the event
Landlord transfers, assigns, or conveys its rights under this lease, Landlord
shall thereby be released from any further obligations hereunder and Tenant
agrees to look solely to such successor in interest of the Landlord for
performance of such obligations so long as (i) any such successor in interest
executes an agreement acceptable to Tenant stating that such successor has
assumed all of the liabilities and obligations of its successor in interest
under this Lease, and (ii) Landlord is not then in default under this Lease.

          (e) Any such sublease or assignment shall not become effective if an
Event of Default by the Tenant granting such sublease or assignment has occurred
and is continuing with respect to the payment of Minimum Rent, electricity costs
or Tenant's Proportionate Share of Excess Operating Costs.

     13.  USE AND OCCUPANCY.

          Tenant agrees that the Leased Premises shall be used and occupied by
Tenant only and then only as and for general business offices and uses
incidental thereto (including but


                                       10

<PAGE>   19

not limited to a shower room, which may be used by Tenant's officers, employees
and guests, but not the general public), and for no other purpose, and Tenant
agrees to use and maintain the Leased Premises (excluding for maintenance
purposes all Building systems, structural elements, load bearing walls (but
including paint or wall coverings on all walls), and core area restrooms] in a
clean, careful, safe, and proper manner and to comply with all laws, ordinances,
orders, rules, and regulations of all governmental bodies (state, federal, and
municipal) applicable or having jurisdiction over Tenant, the Leased Premises,
or the assets of Tenant (such laws, ordinances, orders, rules, decisions, and
regulations being hereinafter called the "Applicable Laws"). Tenant shall not in
any manner deface or injure the Building or the Land or any part thereof or
overload the flouts of the Leased Premises. Tenant shall pay on demand for any
damage to the Leased Premises or to any other part of the Building or the Land
or related improvements or appurtenances caused by any negligence or willful act
or any misuse or abuse (whether or not any such misuse or abuse results from
negligence or willful act) by the Tenant or any of its agents, employees,
licensees, or invitees or any other person (except Landlord, Master Landlord or
any of their respective agents, employees, or contractors) not prohibited,
expressly or impliedly, by Tenant from entering upon the Leased Premises. Tenant
agrees not to use or allow or permit the Leased Premises to be used for any
purpose prohibited by any Applicable Law, or by any restrictive covenants
applicable to the Building and Land, or as a manned express mail pick up center
for such delivery services as Airborne, Federal Express, or for the sale of
bakery products for dessert items including cookies, fudge slices, bar type
cookies and cakes, cupcakes and brownies, whether said product is sold packaged
or unpackaged if such sales would constitute more than ten percent (10%) of
Tenant's gross receipts, and Tenant agrees not to commit waste or suffer or
permit waste to be committed or to allow or permit any nuisance on or in the
Leased Premises. Tenant will not use the Leased Premises for lodging or sleeping
purposes or for any immoral or illegal purposes. Tenant shall not at any time
sell, purchase, or give away, or permit, except with Landlord's prior written
approval, the sale, purchase, or gift of food in any form by or to any of
Tenant's agents or employees or any other parties on the Leased Premises,
excluding vending machines, in-house luncheons and other in-house functions
where food is served. Tenant will conduct its business and occupy the Leased
Premises and will control its agents, employees, licensees, and invitees in such
a manner so as not to create any nuisance or interfere with, annoy, or disturb
any of the other tenants in the Building or Master Landlord in its management of
the Building and so as not to injure the reputation of the Building. Tenant
shall not use the Leased Premises or allow or permit same to be used in any way
or for any purpose that Landlord may deem to be extra hazardous on account of
the possibility of fire or other casualty or which will increase the rate of
fire or other insurance for the Building or its contents or in respect of the
operation of the Building or which may render the Building uninsurable at normal
rates by responsible insurance carriers authorized to do business in the State
of Texas or which may render void or voidable any insurance on the Building and,
in the event that there are increased insurance premiums because of Tenant's use
of the Leased Premises, then, in addition to any other remedies Landlord may
have hereunder, Tenant shall pay such increase to Landlord within five (5) days
of being billed by Landlord therefor. Tenant shall not erect, place, or allow to
be placed any sign, advertising matter, stand, booth, or showcase in or upon the
doorsteps, vestibules, halls, corridors, doors, walls, windows, or pavement of
the Building or the Land (except for lettering on the door or doors to the
Leased Premises as allowed by the Rules and Regulations forming a part of this
Lease) without the prior written consent of Landlord. It is agreed by Landlord
and Tenant that no Rent for the use, occupancy or utilization

                                       11

<PAGE>   20

of the Leased Premises shall be, or is, based in whole or in part on the net
income or profits derived by any person from the Building or the Leased
Premises, and Tenant further agrees that it will not enter into any sublease,
license, concession or other agreement for any use, occupancy or utilization of
the Leased Premises which provides for a rental or other payment for such use,
occupancy or utilization based in whole or in part on the net income or profits
derived by any person from the premises so leased, used, occupied or utilized.
Nothing in the foregoing sentence,, however,, shall be construed as permitting
or constituting Landlord's approval of any sublease, license, concession, or
other use, occupancy, or utilization agreement not otherwise approved by
Landlord in accordance with the provisions of Paragraph 13 hereof.

     14.  ALTERATIONS AND ADDITIONS BY TENANT.

          Tenant shall not make or allow to be made any alterations,
improvements, or additions in or to the Leased Premises without first obtaining
the written consent of Landlord. Landlord may not unreasonably withhold or delay
its consent for non-structural interior alterations, improvements, or additions
to the Leased Premises that do not, as determined by Master Landlord in its sole
discretion, affect any structural element of the Building, any of the Building
operating systems (including branches serving specified tenants), or the
Buildings' appearance. All alterations, additions, and improvements made to or
fixtures or other improvements placed in or upon the Leased Premises, whether
temporary or permanent in character, by either party (except only Tenant's
movable trade fixtures, office furniture and equipment) shall be deemed a part
of the Building and the property of the Landlord at the time same are placed in
or upon the Leased Premises, without compensation to Tenant. Alterations,
improvements, and additions in and to the Leased Premises requested by Tenant
shall be in accordance with plans and specifications which have been previously
submitted to and approved in writing by Landlord. Such work shall be performed
at Tenant's expense and accomplished either by Master Landlord or by contractors
and subcontractors approved in writing by Master Landlord. If such work is not
performed by Master Landlord, then all work performed by other contractors and
subcontractors shall be subject to the following conditions;

                  (a) A certificate of insurance for each contractor and
subcontractor must be submitted to the Landlord and Master Landlord for approval
prior to commencement of construction.

                  (b) Tenant shall ensure that all workers will be cooperative
with Building personnel and comply with all Building rules and regulations.

                  (c) All construction shall be done in a good and workmanlike
manner and shall be subject to approval by Master Landlord in its sole
discretion upon completion.

                  (d) Lien releases from each contractor and subcontractor must
be submitted to the Landlord within five (5) days after completion.

          All alterations and improvements shall comply with all Applicable
Laws, including without limitation, all applicable environmental laws and the
Americans With Disabilities Act of 1990 (the "ADA"). Further, should Tenant's
use of the Leased Premises cause


                                       12

<PAGE>   21

Landlord or Master Landlord to make any alterations or improvements to the
Building (excluding core area restrooms) in order to comply or cause the
Building to comply with the provisions of the ADA, Tenant shall reimburse
Landlord and Master Landlord for the cost of any such alterations or
improvements upon demand.

     15.  REPAIR AND MAINTENANCE BY TENANT.

          Tenant shall keep the Leased Premises (excluding all Building systems,
structural elements, load bearing walls (but including paint or wall coverings
on all walls), and core area restrooms] including all fixtures installed by
Tenant in good and tenantable condition and shall promptly make all necessary
nonstructural repairs and replacements thereto except those caused by fire or
other casualty covered by insurance on the Building under policies naming Master
Landlord as the insured, all at Tenant's sole expense, under the supervision and
with the approval of Landlord. Said repairs and replacements shall be equal in
quality and class to the original work. Without diminishing such obligation of
Tenant, if Tenant fails to make such repairs and replacements within fifteen
(15) days after the occurrence of the damage or injury, Landlord may at its
option make such repairs and replacements and Tenant shall pay Landlord the cost
thereof as additional Rent hereunder upon demand, plus eighteen percent (18%)
per annum interest from demand until payment. In addition, Tenant shall pay the
cost of repair and replacement due to damage or injury done to the Building
(other than the Leased Premises) or the Land or any part thereof by Tenant or
Tenant's agents, employees, or invitees. Such amount shall be paid by Tenant to
Landlord as additional Rent hereunder upon demand, plus eighteen percent (18%)
per annum interest from demand until payment. In the event that Tenant requests
Landlord to perform any maintenance or repairs to the Leased Premises, over and
above any of the services required to be performed by Landlord pursuant to
Paragraph 10, Tenant shall pay the actual cost thereof, plus an administrative
fee equal to 10% of the actual cost thereof, to Landlord within five (5)
business days after demand for same. Landlord hereby assigns to Tenant all of
Landlord's rights relating to Master Landlord's maintenance obligation of the
Leased Premises as set forth in the Master Lease. Landlord shall have no
obligation to Tenant regarding maintenance of the Leased Premises.

     16.  MECHANICS' LIENS.

          Tenant will not permit any mechanic's or materialman's lien or liens
to be placed upon the Leased Premises or improvements thereon or the Land or the
Building during the Lease Term caused by or resulting from any work performed,
materials furnished, or obligation incurred by or at the request of Tenant and
nothing in this Lease contained shall be deemed or construed in any way as
constituting the consent or request of Landlord, express or implied, by
inference or otherwise, to any contractor, subcontractor, laborer, or
materialman for the performance of any labor or the furnishing of any materials
for any specific improvement, alteration, or repair of or to the Leased Premises
or any part thereof, nor as giving Tenant any right, power, or authority to
contract for or permit the rendering of any services or the furnishing of any
materials that would give rise to the filing of any mechanic's, materialman's or
other liens against the interest of Landlord in the Leased Premises. In the case
of the filing of any lien on the interest of Landlord or Tenant in the Leased
Premises, Tenant shall cause the same to be discharged of record within twenty
(20) days after the filing of same. If Tenant shall fail to

                                       13

<PAGE>   22

discharge such lien within such period, then, in addition to any other right or
remedy of Landlord, Landlord may, but shall not be obligated to, discharge the
same either by paying the amount claimed to be due or by procuring the discharge
of such lien by deposit in court or bonding. Any amount paid by Landlord for any
of the aforesaid purposes, or for the satisfaction of any other lien, not caused
or claimed to be caused by Landlord, and all reasonable legal and other expenses
of Landlord, including reasonable counsel fees, in defending any such action or
in or about procuring the discharge of such lien, with all necessary
disbursements in connection therewith, with interest thereon at the rate of
eighteen percent (18%) per annum from the date of payment shall be paid by
Tenant to Landlord on demand.

     17.  Limitations on Liability of Landlord; Waiver; Indemnification by
Landlord

          (a) Neither the Master Landlord nor Landlord shall be liable to Tenant
or to Tenant's agents, contractors, subcontractors, employees, licensees,
servants, and invitees (collectively, the "Tenant Party") or any other person,
and Tenant waives any liability of Landlord, for:

              (1) any injury or damage to person or property due to the
condition or design of, or any defect in, the Project that exists now or occurs
in the future;

              (2) any injury or damage to person or property due to the Project
or related improvements or appurtenances being out of repair, or defects in or
failure of pipes or wiring, or backing up of drains, or the bursting or leaking
of pipes, faucets and plumbing fixtures, or gas, water, steam, electricity, or
oil leaking, escaping or flowing into the Leased Premises;

              (3) any loss or damage to property or person occasioned by theft,
fire, act of God, public enemy, injunction, riot, insurrection, war, court
order, requisition, order of governmental authority and any other cause beyond
the control of Landlord or Master Landlord;

              unless caused by the gross negligence or intentional torts of
Landlord or Master Landlord, or their respective agents, employees or contracts
("Landlord's Acts").

          (b) Landlord shall indemnify, defend and hold Tenant harmless from all
death, bodily injury, loss, claims or damage to any person or property (other
than Insurable Claims (defined below) to Tenant's property) caused by any breach
of Landlord of any express representation or warranty by Landlord in this Lease,
the failure of Landlord to comply with its obligations under this Lease, or
Landlord's Acts, except to the extent caused by Tenant's Acts (defined below).
If death, bodily injury, loss, claims or damage to any person or property (other
than Insurable Claims to Tenant's property) is caused by Landlord's Acts and
Tenant's Acts jointly, Landlord's indemnity in this subparagraph is in
proportion to its allocable share of the joint negligence or intentional tort.

          (c) Notwithstanding the foregoing or anything else to the contrary
contained in this Lease, the liability of Landlord to any Tenant Party for any
default or indemnity by landlord under this Lease is limited to the interest of
Landlord in the Project. Neither Landlord nor any partner, employee, agent,
director or officer of Landlord has any personal liability for any amounts
payable or obligations performable by Landlord under this Lease.


                                       14

<PAGE>   23

     18.  Tenant's Indemnification of Landlord.

          (a) Tenant shall indemnify, defend and hold Landlord harmless from all
death, bodily injury, loss, claims or damage to any person or property (other
than Insurable claims to Landlord's property) caused by any breach of Tenant of
any express representation or warranty by Tenant in this Lease, the failure of
Tenant to comply with its obligations under this Lease, or the negligence or
intentional tort of any Tenant Party ("Tenant Acts") except to the extent caused
by Landlord's Acts. If death, bodily injury, loss, claims or damage to any
person or property (other than Insurable Claims to Landlord's property) is
caused by Landlord's Acts and Tenant's Acts jointly, Tenant's indemnity in this
subparagraph is in proportion to its allocable share of the joint negligence or
intentional tort.

          (b) The term "Insurable Claim" means a claim that can be covered by
the standard form of "broad form" property (casualty) policies, with Vandalism
and Malicious Mischief Endorsements, as promulgated by the Texas State Board of
Insurance (without regard to the purchase of any policy).

          (c) Tenant, for itself and all other Tenant Parties, assumes all risks
of injury or damage to person or property, either proximate or remote, by reason
of the condition or design of, or any defects (excluding latent defects,
including structural defects) in, the Leased Premises and the Project.

          (d) All personal property of Tenant Parties in the Leased Premises is
at the sole risk of Tenant.

          (e) The provisions of this Paragraph shall survive the expiration or
earlier termination of this Lease.

     19.  Tenant's Insurance.

          Tenant shall, at its sole cost and expense, procure and maintain
through the term of this Lease a policy or policies of insurance insuring Tenant
against any and all liability for injury to or death of a person or persons and
for damage to or destruction of property occasioned by or arising out of or in
connection with the use or occupancy of the Leased Premises or by the condition
of the Leased Premises (including the contractual liability of Tenant to
indemnify Landlord contained herein) with a combined single limit of
$1,000,000.00 for bodily injury and/or property damages, or with such other
limits as may be required by Landlord, and to be written by an insurance company
or companies satisfactory to Landlord and licensed to do business in the State
of Texas with Landlord named as an additional insured. If Tenant has an umbrella
or excess policy, Tenant will name Master Landlord, Landlord and Master
Landlord's manager, as additional named insureds on all layers of umbrella or
excess policies. Tenant shall obtain a written obligation on the part of each
insurance company to notify Landlord at least thirty (30) days prior to
cancellation of such insurance. Such policies or duly executed certificates of
insurance relating thereto shall be promptly delivered to Landlord within five
(5)

                                       15


<PAGE>   24

days after the execution of this Lease and renewals thereof as required shall be
delivered to Landlord at least fifteen (15) days prior to the expiration of the
respective policy terms. In addition to all other remedies Landlord may have
under this Lease, if Tenant fails to comply with the foregoing requirements
relating to insurance, Landlord may obtain such insurance and Tenant shall pay
as additional Rent to Landlord on demand the premium cost thereof plus interest
at the rate of eighteen percent (18%) per annum from the date of payment by
Landlord until repaid by Tenant.

     20.  LANDLORD'S INSURANCE.

          Landlord agrees to cause Master Landlord to carry during the term
hereof, public liability insurance providing limits of liability of not less
than One Million Dollars ($1,000,000.00) for personal injury or death arising
out of any one occurrence. Landlord also agrees to cause Master Landlord to
carry, during the term hereof, insurance for fire, extended coverage, vandalism
and malicious mischief, insuring the Building, including the Leased Premises and
all appurtenances thereto for the full insurable value thereof, such insurance
coverage to exclude Tenant's merchandise, trade fixtures, furnishings,
equipment, personal property, and any alterations or additions made and paid for
by Tenant, unless Landlord or Master Landlord elects otherwise. Such policies or
duly executed certificates of insurance relating thereto shall be promptly
delivered to Tenant within five (5) days after the execution of this Lease and
renewals thereof as required shall be delivered to Tenant at least fifteen (15)
days prior to the expiration of the respective policy terms. In addition to all
other remedies Tenant may have under this lease, if Landlord fails to comply
with the foregoing requirements relating to insurance, Tenant may obtain such
insurance and Landlord shall pay to Tenant on demand the premium costs thereof
plus interest at the rate of eighteen percent (18%) per annum from the date of
payment by Tenant until repaid by Landlord.

     21.  CERTAIN RIGHTS RESERVED BY LANDLORD.

          So long as this Lease is in full force and effect, Master Landlord and
Landlord shall have the following rights, exercisable without notice and without
liability to Tenant for damage or injury to property, persons, or business and
without effecting an eviction, constructive or actual, or disturbance of
Tenant-Is use or possession or giving rise to any claim for setoff or abatement
of Rent:

          (a) To change the Building's name or street address.

          (b) To install, affix, and maintain any and all signs on the exterior
and interior of the Building.

          (c) To designate and approve, prior to installation, all types of
window shades, blinds, drapes, awnings, window ventilators, and similar
equipment, and to control all internal lighting that may be visible from the
exterior of the Building.

          (d) To designate, restrict, and control all sources within the
Building from which Tenant may obtain ice, drinking water, towels, toilet
supplies, catering, food and beverages, or like or other services on the Leased
Premises.


                                       16
<PAGE>   25

          (e) To enter upon the Leased Premises at reasonable hours to inspect
same or clean or make repairs or alterations (but without any obligation to do
so, except as expressly provided for herein) or to show the Leased Premises to
prospective lenders or purchasers, and, during the last twelve (12) months of
the Lease Term, to show the Leased Premises to prospective tenants at reasonable
hours and, if the Leased Premises are vacant, to prepare same for re-occupancy.

          (f) To retain at all times, and to use in appropriate instances, keys
to all doors within and into the Lease Premises. No locks shall be changed or
added without the prior written consent of Landlord.

          (g) To decorate and to make repairs, alterations, additions, changes,
or improvements, whether structural or otherwise, in and about the Building or
any part thereof, and for such purposes to enter upon the Leased Premises and,
during the continuance of any of said work, to temporarily close doors,
entryways, public space, and corridors in the Building to interrupt or
temporarily suspend Building services and facilities and to change the
arrangement and location of entrances or passageways, doors and doorways,
corridors, elevators, stairs, toilets, or other public parts of the Building,
all without abatement of Rent or affecting any of Tenant's obligations
hereunder, so long as the Leased Premises are reasonably accessible.

          (h) To have and retain a paramount title to the Leased Premises free
and clear of any act of Tenant purporting to burden or encumber them.

          (i) To grant to anyone the exclusive right to conduct any business or
render any service in or to the Building, provided such exclusive right shall
not operate to exclude Tenant from the use expressly permitted herein.

          (j) To approve the weight, size, and location of safes and other heavy
equipment and articles in and about the Leased Premises and the Building and to
require all such items and furniture and similar items to be moved into and out
of the Building and Leased Premises only at such times and in such manner as
Landlord shall direct in writing. Movements of Tenant's property into or out of
the Building and within the Building are entirely at the risk and responsibility
of Tenant and Landlord reserves the right to require permits before allowing
such property to be moved into or out of the Building.

          (k) To have access for Landlord and other tenants of the Building to
any mail chutes or other depositories located on the Leased Premises according
to the rules of the United States Postal Service.

          (1) To take all such reasonable measures for the security of the
Building and its occupants, including without limitation, the search of all
persons entering or leaving the Building, the evacuation of the Building for
cause, suspected cause, or for drill purposes, the temporary denial of access to
the Building, and the closing of the Building after regular working hours, i.e.,
7:30 a.m. to 6:00 p.m. on business days and on Saturdays, Sundays, and legal
holidays, subject, however, to Tenant's right to admittance when the Building is
closed after


                                       17


<PAGE>   26

regular working hours under such reasonable regulations as may be prescribed
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 regular
working hours, identify themselves to a security officer by registration or
otherwise and that said persons establish their right to enter or leave the
Building.

     22.  FIRE OR OTHER CASUALTY.

          If the Leased Premises or any part thereof shall be damaged by fire or
other casualty, Tenant shall give prompt written notice thereof to Landlord. In
case the Building shall be so damaged by fire or other casualty that substantial
alteration or reconstruction of the Building shall, in Master Landlord's sale
opinion, be required (whether or not the Leased Premises shall have been damaged
by such fire or other casualty) or in the event any mortgagee under a mortgage
or deed of trust covering the Building should require that the insurance
proceeds payable as a result of said fire or other casualty be used to retire
the mortgage debt, Landlord may, at its option, terminate this Lease and the
term and estate hereby granted by notifying Tenant in writing of such
termination within seventy (70) days after the date of such damage, in which
event the Rent hereunder shall be abated as of the date of such damage. Landlord
hereby assigns to Tenant all of Landlord's rights pursuant to Paragraph 23 of
the Master Lease to have Master Landlord repair all or any portion of the Leased
Premises and any part of the Building and/or Common Area that are so damaged by
any casualty as to render all or a portion of the Leased Premises unusable. Such
repair rights of Tenant shall be subject-to the limitations of Paragraph 23 of
the Master Lease. Landlord shall not be liable for any inconvenience or
annoyance to Tenant or injury to the business of Tenant resulting in any way
from such damage or the repair thereof; except that during the time and to the
extent that the Leased Premises are unfit for occupancy, there shall be a fair
diminution of Rent. If the damages are caused by the negligence of Tenant, its
agents, servants, employees, contractors, patrons, guests, licensees, or
invitees there will be no abatement of Rent and Tenant will be liable for any
damages in excess of the amount paid by insurance proceeds received by Landlord.
Any insurance which may be carried by Landlord or Tenant against loss or damage
to the Building or to the Leased Premises shall be for the sole benefit of the
party carrying such insurance and under its sole control.

     23.  CONDEMNATION.

          If the whole or substantially the whole of the Building and Land or of
the Leased Premises should be taken for any public or quasi-public use under any
governmental law, ordinance or regulation or by right of eminent domain or
should be sold to the condemning authority in lieu of condemnation, then this
Lease shall terminate as of the date when physical possession of the Building
and Land or the Leased Premises is taken by the condemning authority. If less
than the whole or substantially the whole of the Building and Land or the Leased
Premises is thus taken or sold, Landlord (whether or not the Leased Premises are
affected thereby) may terminate this Lease by giving written notice thereof to
Tenant within sixty (60) days after the right of election accrues, in which
event this Lease shall terminate as of the date when physical possession of such
portion of the Building and Land or Leased Premises is taken by the condemning
authority. If upon any such taking or sale of less than the whole or


                                       18
<PAGE>   27
substantially the whole of the Building and Land or the Leased Premises this
Lease shall not be thus terminated, the Rent payable hereunder shall be
diminished by an amount representing that part of said Rent as shall properly be
allocable to the portion of the Leased Premises which was so taken or sold.
Landlord hereby assigns to Tenant all of Landlord's rights pursuant to Paragraph
24 of the Master Lease to have Master Landlord repair or restore all or any part
of the Leased Premises in any part of the Building and/or the Common Area that
are damaged by any such condemnation. Landlord shall be entitled to receive all
of the compensation awarded upon a taking of any part or all of the Building and
Land or the Leased Premises including any award for the value of unexpired term
of this Lease and Tenant shall not be entitled to and expressly waives all claim
to any such compensation; provided, however, Tenant shall be entitled to receive
an award for damages to Tenant's leasehold improvements.

         24.      TAXES ON TENANT'S PROPERTY.

                  Tenant shall be liable for all taxes levied or assessed
against personal property, furniture, fixtures, or other improvements placed by
Tenant in the Leased Premises, but specifically excluding Tenant Improvements
(hereinafter defined) paid for by Landlord. If any such taxes for which Tenant
is liable are levied or assessed against Landlord or Landlord's property and if
Landlord is required to pay the same or if the assessed value of Landlord's
property is increased by inclusion of personal property, furniture, fixtures, or
other improvements placed by Tenant in the Leased Premises and Landlord elects
to pay the taxes based on such increase, Tenant shall pay to Landlord upon
demand that part of such taxes for which Tenant is liable hereunder.

         25.      WAIVER OF SUBROGATION.

                  Notwithstanding anything to the contrary contained in this
Lease, each party hereto hereby waives any and every claim which arises or may
arise in its favor and against the other patty hereto, or anyone claiming
through or under them, by way of subrogation or otherwise, during the Lease Term
or any extension or renewal thereof for any and all loss of, or damage to, any
of its property (whether or not such loss or damage is caused by the fault or
negligence of the other party or anyone for whom said other party may be
responsible), which loss or damage is covered by valid and collectible fire and
extended coverage insurance policies, to the extent that such loss or damage is
recovered under said insurance policies. Said waivers shall be in addition to,
and not in limitation or derogation of, any other waiver or release contained in
this Lease with respect to any loss or damage to property of the parties hereto.
Inasmuch as the above mutual waivers will preclude the assignment of any
aforesaid claim by way of subrogation (or otherwise) to an insurance company (or
any other person), each party hereto hereby agrees immediately to give each
insurance company which has issued to it policies of fire and extended coverage
insurance written notice of the terms of said mutual waivers, and to have said
insurance policies properly endorsed, if necessary, to prevent the invalidation
of said insurance coverages by reason of said waivers.

         26.      SURRENDER UPON TERMINATION OR EXPIRATION.

At the expiration of the Lease Term or any termination of this Lease, Tenant
shall at once


                                       19
<PAGE>   28


surrender possession of the Leased Premises and deliver the Leased Premises to
Landlord in as good repair and condition as at the commencement of Tenant's
occupancy, reasonable wear and tear and damages or destruction by fire or other
insured casualty excepted, and shall deliver to Landlord all keys to the Leased
Premises, and, if such possession is not immediately surrendered, Landlord may
forthwith enter upon and take possession of the Leased Premises and expel or
remove Tenant and any other person who may be occupying said premises, or any
part thereof, by force, if necessary, without having any civil or criminal
liability therefor. All alterations, additions, or improvements (except Tenant's
trade fixtures, movable office furniture and equipment), made in or upon the
Leased Premises, either by Landlord or Tenant, shall be Landlord's property on
termination of this Lease or expiration of the Lease Term and shall remain on
the Leased Premises without compensation to Tenant. All furniture, movable trade
fixtures, and equipment installed by Tenant may be removed by Tenant at the
termination of this Lease or the expiration of the Lease Term. All such removals
shall be accomplished in a good workmanlike manner so as not to damage the
Leased Premises or the primary structure or structural qualities of the Building
or the plumbing, electrical lines, and other utilities serving the Leased
Premises or the Building. Tenant, or Landlord at Tenant's expense, shall repair
any damage to the Leased Premises, the Building, and Land caused by any such
removal. All furniture, movable trade fixtures and equipment installed by Tenant
not removed within fifteen (15) days after such termination or expiration shall
thereupon be conclusively presumed to have been abandoned by Tenant and Landlord
may, at its option, take over the possession of such property and either (i)
declare same to be the property of Landlord by written notice thereof to Tenant
or (ii) at the sole risk, cost, and expense of Tenant remove the same or any
part thereof in any manner that Landlord shall choose and store the same without
incurring liability to Tenant or any other person.

         27.      EVENTS OF DEFAULT.

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

                           (a) Tenant shall fail to pay any Rent and such
failure shall continue for a period of five (5) business days.

                           (b) Tenant shall fail to comply with any term,
provision, or covenant of this Lease, other than the payment of Rent, and shall
not cure such failure within thirty (30) days after delivery to Tenant of
written notice of the occurrence of such failure; provided, if the failure is of
a nature that it cannot, with due diligence, be cured within thirty (30) days,
it is not an Event of Default if Tenant begins to cure the failure within 30
days and diligently pursues the cure to completion within sixty (60) days;

                           (c) Tenant shall become insolvent, or shall make a
transfer in fraud of creditors, or shall commit any act of bankruptcy or shall
make an assignment for the benefit of creditors, or Tenant shall admit in
writing its inability to pay its-debts as they become due.

                           (d) Tenant shall file a petition under any section or
chapter of the Bankruptcy Code of the United States, as amended, or under any
similar law or statute of the


                                       20
<PAGE>   29


United States or any state thereof, or Tenant shall be adjudged bankrupt or
insolvent in proceedings filed against Tenant thereunder; or a petition or
answer proposing the adjudication of Tenant as a bankrupt or its reorganization
under any present or future federal or state bankruptcy or similar law shall be
filed in any court and such petition or answer shall not be discharged or denied
within one hundred twenty (120) days after the filing thereof.

                           (e) A receiver or trustee shall be appointed for all
or substantially all of the assets of Tenant or of the Leased Premises or of any
of Tenant's property located thereon in any proceeding brought by Tenant, or any
such receiver or trustee shall be appointed in any proceeding brought against
Tenant and shall not be discharged within one hundred twenty (120) days after
such appointment or Tenant shall consent to or acquiesce in such appointment.

                           (f) Tenant, if a natural person, shall die or become
incapacitated, or if Tenant is not a natural person, Tenant shall dissolve or
cease to exist.

                           (g) The leasehold estate hereunder shall be taken on
execution or other process of law in any action against Tenant.

                           (h) Tenant vacates without paying Rent any
substantial portion of the Leased Premises for a period of time in excess of
five (5) days without written permission of Landlord.

         28.      LANDLORD'S REMEDIES.

                  If an Event of Default shall have occurred, Landlord shall
have the right at its election, then or any time thereafter while such Event of
Default shall continue, to pursue any one or more of the following remedies:

                           (a) Terminate this Lease by giving notice thereof to
Tenant, in which event Tenant shall immediately surrender the Leased Premises
to Landlord and if Tenant fails so to do, Landlord may without prejudice to any
other remedy which it may have for possession or arrearages in Rent, enter upon
and take possession of the Leased Premises and expel or remove Tenant and any
other person who may be occupying said premises, or any part thereof, without
being liable for prosecution or any claim of damages therefor and Tenant hereby
agrees to pay to Landlord on demand the amount of all loss and damage which
Landlord may suffer by reason of such termination, whether through inability to
relet the Legal Premises on satisfactory terms or otherwise, it being understood
and agreed by Tenant that Landlord shall have no obligation or duty to relet the
Leased Premises, specifically including but not limited to (1) all reasonable
expenses necessary to relet the Leased Premises which shall include the cost of
renovating, repairing, and altering the Leased Premises for a new tenant or
tenants, advertisements and brokerage fees; and (2) any increase in insurance
premiums caused by the vacancy of the Leased Premises. Nothing contained in this
Lease shall limit or prejudice the right of Landlord to prove for and obtain in
proceedings for bankruptcy or insolvency by reason of the termination of this
Lease, an amount equal to the maximum allowed by any statute or rule of law in
effect at the time when, and governing the proceedings in which, the damages are
to be proved, whether or not the amount be greater, equal to, or less than the
amount of the loss or damages referred to above.


                                       21
<PAGE>   30


                           (b) Enter upon and take possession of the Leased
Premises and expel or remove Tenant or any other person who may be occupying
said premises, or any part thereof, without having any civil or criminal
liability therefor and without terminating this Lease. Landlord may (but shall
be under no obligation to) relet the Leased Premises or any part thereof for the
account of Tenant, in the name of Tenant or Landlord or otherwise, without
notice to Tenant for such term or terms (,which may be greater or less than the
period which would otherwise have constituted the balance of the term of this
Lease) and on such conditions (which may include concessions or free rent) and
for such uses as Landlord in its absolute discretion may determine and Landlord
may collect and receive any rents payable by reason of such reletting; and
Tenant agrees to pay Landlord on demand all reasonable expenses necessary to
relet the Leased Premises which shall include the cost of renovating, repairing,
and altering the Leased Premises for a new tenant or tenants, advertisements and
brokerage fees, and Tenant further agrees to pay Landlord on demand any
deficiency that may arise by reason of such reletting. Landlord shall not be
responsible or liable for any failure to relet the Leased Premises or any part
thereof or for any failure to collect any Rent due upon any such reletting. No
such reentry or taking of possession of the Leased Premises by Landlord shall be
construed as an election on Landlord's part to terminate this Lease unless a
written notice of such termination is given to Tenant pursuant to subparagraph
above.

                           (c) Enter upon the Leased Premises without having any
civil or criminal liability therefor, and do whatever Tenant is obligated to do
under the terms of this Lease and Tenant agrees to reimburse Landlord on demand
for any expenses which Landlord may incur in thus affecting compliance with
Tenant's obligations under this Lease together with interest at the rate of
eighteen percent (18%) per annum, and Tenant further agrees that Landlord shall
not be liable for any damages resulting to Tenant from such action, whether
caused by the negligence of Landlord or otherwise.

                           (d) Landlord may, without further notice of any kind
to Tenant, interrupt or cause the interruption of any utility service serving
the Leased Premises, remove, alter, or change any door, window, attic hatchway
cover to the Leased Premises, or any lock, latch, hinge, hinge pin, doorknob, or
other mechanism connected to any door, window, or attic hatchway cover to the
Leased Premises, and intentionally prevent Tenant from entering the Leased
Premises without resort to judicial process. Landlord shall be under no
obligation to restore any such door, window, or attic hatchway cover or any
lock, latch, hinge, hinge pin, doorknob, or other mechanism attached thereto or
to deliver or make available to Tenant any key to any such door, window, or
attic hatchway cover unless and until Tenant fully cures all Events of Default
then existing under this Lease.

                  No repossession or reentering on the Leased Premises or any
part thereof pursuant to this Lease and no reletting of the Leased Premises or
any part thereof pursuant to subparagraph shall relieve Tenant of its
liabilities and obligations hereunder, all of which shall survive such
repossession or reentering. In the event of any such repossession or re-entering
on the Leased Premises or any part thereof by reason of the occurrence of an
Event of Default, Tenant will pay to Landlord the Rent required to be paid by
Tenant. No right or remedy herein


                                       22
<PAGE>   31


conferred upon or reserved to Landlord is intended to be exclusive of any other
right or remedy, and each and every right and remedy shall be cumulative and in
addition to any other right or remedy given hereunder or now or hereafter
existing at law or in equity or by statute. In addition to other remedies
provided in this Lease, Landlord shall be entitled, to the extent permitted by
applicable law, to injunctive relief in case of the violation, or attempted or
threatened violation, of any of the covenants, agreements, conditions, or
provisions of this Lease, or to a decree compelling performance of any of the
other covenants, agreements, conditions, or provisions of this Lease, or to any
other remedy allowed to Landlord at law or in equity.

                  If Tenant shall be in default under this Lease such that a
default by Landlord under the Master Lease is also created, then notwithstanding
the notice and cure provisions set forth in this Lease, the time in which Tenant
shall be required to cure any such default of Tenant shall be the lesser of (i)
any such time periods established by this Lease or (ii) the time remaining under
the terms of the Master Lease for Landlord to cure after Master Landlord has
given notice of such default to Landlord. Landlord shall provide to Tenant a
copy of any such notice of default from Master Landlord within one (1) business
day after Landlord's receipt of such notice.

         29.      NO IMPLIED WAIVER.

                  The failure of Landlord or Tenant to insist at any time upon
the strict performance of any covenant or agreement or to exercise any option,
right, power, or remedy contained in this Lease shall not be construed as a
waiver or a relinquishment thereof for the future. The waiver of or redress for
any violation of any term, covenant, agreement, or condition contained in this
Lease or contained in the Rules and Regulations attached to and forming a part
of this Lease shall not prevent a subsequent act, which would have originally
constituted a violation from having all the force and effect of an original
violation. No express waiver shall affect any condition other than the one
specified in such waiver and that one only for the time and in the manner
specifically stated. A receipt by Landlord of any Rent with knowledge of the
breach of any covenant or agreement contained in this Lease shall not be deemed
a waiver of such breach, and no waiver by Landlord of any provision of this
Lease shall be deemed to have been made unless expressed in writing and signed
by Landlord.

         30.      WAIVER BY TENANT.

                  Tenant hereby waives and surrenders for itself and all
claiming by, through, and under it, including creditors of all kinds, any
rights, privileges, and liens set out under Section 91.004 of the Texas Property
Code (as amended) and hereby exempts Landlord from any liability or duty
thereunder.

         31.      ATTORNEYS' FEES AND LEGAL EXPENSES.

                  In the event of litigation concerning the interpretation or
enforcement of this Lease, the prevailing party shall be entitled to recover
from the losing party its attorneys' fees, court costs, and expenses, whether at
the trial or appellate level.


                                       23
<PAGE>   32


         32.      SUBORDINATION.

                  At the option of Master Landlord's first mortgagee, this Lease
and all rights of Tenant hereunder shall be subject and subordinate (i) to any
first mortgage or first deed of trust, blanket or otherwise, which does now or
may hereafter affect the Building (and which may also affect other property and
(ii) to any and all increases, renewals, modifications, consolidations,
replacements, and extensions of any such mortgage or deed of trust. If Master
Landlord's first mortgagee elects to make this Lease subordinate, Landlord and
Tenant shall, however, upon demand at any time or times execute, acknowledge,
and deliver to each other, or to Master Landlord's first mortgagee, a
Subordination, Non-Disturbance and Attornment Agreement, substantially in the
form of Exhibit G. In the event Tenant shall fail or neglect to execute,
acknowledge, and deliver any such subordination agreement or certificate,
Landlord, in addition to any other remedies it may have, as the agent and
attorney in fact of Tenant, execute, acknowledge, and deliver the same and
Tenant hereby irrevocably nominates, constitutes and appoints Landlord as
Tenant's proper and legal agent and attorney in fact for such purposes. Such
power of attorney shall not terminate on disability of the principal. Tenant
covenants and agrees, in the event any proceedings are brought for the
foreclosure of any such mortgage or if the Building be sold pursuant to any such
deed of trust, to attorn to the purchaser upon any such foreclosure sale or
trustee's sale if so requested by such purchaser and to recognize such purchaser
as the Landlord under this Lease. Tenant agrees to execute, acknowledge and
deliver at any time and from time to time, upon the request of Landlord or any
holder(s) of any of the indebtedness or other obligations secured by any of the
mortgages or deeds of trust referred to in this paragraph any instrument at
certificate which, in the sole judgment of Landlord or of such holder(s), may be
necessary or appropriate in any such foreclosure proceeding or otherwise to
evidence such attornment. Tenant hereby irrevocably appoints Landlord and the
holder(s) of the indebtedness or other obligations secured by the aforesaid
mortgages and/or deeds of trust jointly and severally the agent and attorney in
fact of Tenant to execute and deliver for and on behalf of Tenant any such
instrument or certificate. Such power of attorney shall not terminate on
disability of the principal. Tenant further waives the provisions of any statute
or rule of law, now or hereafter in effect, which may give or purport to give
Tenant any right or election to terminate or otherwise adversely affect this
Lease and the obligation of Tenant hereunder in the event any such foreclosure
proceeding is brought or trustee's sale occurs and agrees that this Lease shall
not be affected in any way whatsoever by any such foreclosure proceeding or
trustee's sale unless the holder(s) of the indebtedness or other obligations
secured by said mortgages and/or deeds of trust shall declare otherwise. This
Lease and all rights of Tenant hereunder are further subject and subordinate, to
the extent that the same relate to the Leased Premises, to all Applicable Laws
and to all liens, leases, restrictions, easements, and encumbrances to the
extent same are valid, subsisting, and recorded in the Real Property Records of
Dallas County, Texas.

         33.      QUIET ENJOYMENT.

                  Provided Tenant pays the Rent payable hereunder as and when
due and payable and keeps and fulfills all of the terms, covenants, agreements,
and conditions to be performed by Tenant hereunder, Tenant shall at all times
during the Lease Term peaceably and quietly enjoy the Leased Premises without
any disturbance from Landlord or from any other person claiming


                                       24
<PAGE>   33

by, through, or under Landlord, subject to the terms, provisions, covenants,
agreements, and conditions of this Lease and to the deeds of trust, mortgages,
ground leases, ordinances, leases, utility easements, and agreements to which
this Lease is subject and subordinate, as hereinabove set forth. Notwithstanding
any of the provisions of this Paragraph, Landlord shall not be responsible for
and shall not be liable to Tenant for any damages due to any interference with
Tenant's quiet enjoyment of the Leased Premises due to any default under the
Master Lease unless and to the extent that such default is caused by Landlord.

         34.      NOTICE DUE TO LANDLORD.

                  In the event of any act or omission by Landlord which would
give Tenant the right to damages from Landlord or the right to terminate this
Lease by reason of a constructive or actual eviction from all or part of the
Leased Premises or otherwise, Tenant shall not sue for such damages or exercise
any such right to terminate until (i) it shall have given written notice of such
act or omission to Landlord and (ii) a reasonable period of time for remedying
such act or omission shall have elapsed following the giving of such notice,
during which time Landlord, its agents, employees or its mortgagee shall be
entitled to enter upon the Leased Premises and do therein whatever may be
necessary to remedy such act of omission. During the period after the giving of
such notice and during the remedying of such act or omission, the Rent payable
by Tenant for such period as provided in this Lease shall be abated and
apportioned only to the extent that any part of the Leased Premises shall be
untenantable.

         35.      HOLDING OVER BY TENANT.

                  Should Tenant or any of its successors in interest continue to
hold the Leased Premises after the termination or expiration of this Lease, such
holding over shall constitute and be construed as a tenancy from month to month
only, at a monthly rental equal to 150% of the amount of the monthly
installments of Minimum Rent at the time of such termination or expiration, plus
the payment of all other Rent payable hereunder at the time of such termination
or expiration. During such time as Tenant shall continue to hold the Leased
Premises after the termination or expiration hereof, Tenant shall be regarded as
a tenant from month to month; subject, however, to all of the terms,
provisions, covenants, and agreements on the part of Tenant hereunder. No
payments of money by Tenant to Landlord after the termination or expiration of
this Lease shall reinstate, continue, or extend the term of this Lease and no
extension of this Lease after the termination or expiration thereof shall be
valid unless and until the same shall be reduced to writing and signed by both
Landlord and Tenant. Nothing in this paragraph should be construed as giving
Tenant the right to hold over beyond the Expiration Date nor preclude Landlord
from having the right to dispossess or otherwise terminate Tenant's right of
possession. Any month-to-month tenancy is terminable upon notice from Landlord.

         36.      RULES AND REGULATIONS.

                  Tenant and Tenant's agents, employees, and invitees will
comply with all requirements of the Rules and Regulations (as changed from time
to time as hereinafter provided) which are attached hereto as Exhibit E and made
a part hereof as though fully set out herein. Master Landlord shall at all times
have the right to change such Rules and Regulations or


                                       25
<PAGE>   34


to promulgate other Rules and Regulations in such reasonable manner as may be
deemed advisable for the safety, care, or cleanliness of the Building and
related facilities or premises, and for preservation of good order therein;
provided, no new Rules and Regulations may unreasonably and materially,
adversely interfere with Tenant's use of the Leased Premises or require Tenant
to pay additional Rent. No changes shall become effective and a part of this
Lease until a copy thereof shall have been delivered to Tenant. Tenant shall
further be responsible for the compliance with such Rules and Regulations by the
employees, servants, agents, visitors, and invitees of Tenant. Landlord shall
use its best efforts to secure compliance by all tenants and other persons with
the Rules and Regulations from time to time in effect, but shall not be
responsible to Tenant for failure of any person to comply with such Rules and
Regulations.

         37.      ESTOPPEL CERTIFICATE.

                  Tenant will, at any time and from time to time, upon not less
than twenty (20) days' prior request by Landlord, execute, acknowledge, and
deliver to Landlord a statement in writing executed by Tenant certifying that
this Lease is the entire agreement between the parties and is unmodified and in
full effect (or, if there have been modifications, that this Lease is in full
effect as modified, and setting forth such modifications) and the dates to which
the Rent has been paid, that the Tenant has unconditionally accepted the Leased
Premises, and either stating that to the knowledge of the signer of such
certificate no default exists hereunder or specifying each such default of which
the signer may have knowledge; it being intended that any such statement by
Tenant may be relied upon by any prospective purchaser or mortgagee of the
Building.

         38.      NOTICES.

                  Each provision of this Lease, or of any applicable
governmental laws, ordinances, regulations, and other requirements with
reference to the sending, mailing, or delivery of any notice or with reference
to the making of any payment by Tenant to Landlord, shall be deemed to be
complied with when and if the following steps are taken:

                           (a) All Rent and other payments required to be made
by Tenant to Landlord hereunder shall be payable to Landlord in Dallas County,
Texas at the address set forth in the Basic Lease Provisions, or at such other
address as Landlord may specify from time to time by written notice delivered in
accordance herewith.

                           (b) Any notice or document required to be delivered
hereunder shall be deemed to be delivered, whether actually received or not,
when deposited in the United States mail, postage paid, certified or registered
mail, return receipt requested, addressed to the parties hereto at the
respective addresses set out opposite their names in the Basic Lease Provisions,
or at such other address as they have theretofore specified by written notice.

         39.      ROOF COMMUNICATION ACCESS AND OTHER RIGHTS.

                  Tenant shall have the right to use the then currently
available portions of the Central Tower Building roof, pipe chase space and
conduits as needed for Tenant's


                                       26
<PAGE>   35


telecommunications equipment (including but not limited to satellite dish,
microwave dish and antenna), cabling and fiber optics, supplemental HVAC
equipment, and other such facilities, at no additional cost other than Tenant's
expenditures for installation, repair, operation and maintenance. Such access
rights shall be coterminous with the Lease Term. All such facilities must be
limited to an area designated by Landlord and must be installed in compliance
with all architectural guidelines for the Project and all Applicable Laws.
Tenant shall pay all costs of removal of such facilities upon the expiration or
earlier termination of this Lease and shall also pay for any repairs of roof
penetrations caused by the installation of such facilities. Specifications for
such equipment including installation and location shall meet Sublessor's
reasonable approval.

         40.      REPRESENTATIONS AND WARRANTIES OF LANDLORD.

                  Landlord hereby warrants and represents the following:

                  Landlord is the current Tenant under that certain Office Space
Lease (the "Master Lease") dated as of October 4, 1993, by and between T-Las
Colinas Towers Corp., a Delaware corporation, as the landlord and the Landlord
as the Tenant, as the same may now be hereinafter be amended, pursuant to which
Master Landlord leased the Master Premises to Landlord. The Leased Premises is a
part of the Master Premises. without the prior written consent of Tenant, which
consent shall not be unreasonably withheld, Landlord shall not amend or modify
the Master Lease in a manner which adversely affects Tenant.

                  (a) Landlord is duly authorized to execute and to enter into
this Lease and this Lease is a legal, binding, and valid obligation of Landlord,
enforceable in accordance with its terms.

                  (b) The execution and delivery of this Lease by Landlord will
not conflict with or cause a default by Landlord under any laws, rules,
regulations or court orders of any governmental authority, the Master Lease or
any agreement or prior lease to which Landlord is a party or by which any of its
assets are bound, nor will this Lease create any conflict with the rights of any
other tenant in the Project.

                  (c) There is no default by Landlord under the Master Lease,
and to Landlord's knowledge, no default thereunder by Master Landlord.

                  (d) With respect to environmental matters, Landlord has no
knowledge that:

                           (i) The Leased Premises are not in compliance with
all Environmental Requirements, or that there are any Hazardous Materials
(hereinafter defined) on, under, or in the Project or the Leased Premises in
amounts or concentrations that require investigation or remedial or removal
action.

                           (ii) The Leased Premises contain any asbestos,
whether friable or not.

                           (iii) Landlord or any officer or employee thereof has
received any


                                       27
<PAGE>   36


notice or other communication concerning (A) any violation or alleged or
probable violation of Environmental Requirements, whether or not corrected to
the satisfaction of the appropriate authority or (B) any alleged liability for
environmental damages in connection with any portion of the Leased Premises. Any
writ, injunction, decree, order or judgment relating to the foregoing is
outstanding. There is any lawsuit, claim, proceeding, citation, directive,
summons or investigation, pending or threatened, relating to any alleged
violation of any applicable Environmental Requirements or the suspected presence
of any Hazardous Materials at the Leased Premises.

                           (iv) For the purposes of this Lease, the term
"Hazardous Materials" shall mean any substance: (A) the presence of which
requires investigation or remediation under any applicable federal, state or
local statute, regulation, or ordinance concerning environmental matters; (B)
that is or becomes defined as a hazardous waste or hazardous substance under any
applicable federal, state, or local statute, regulation or ordinance concerning
environmental matters; or (C) that contains PCBs in excess of authorized levels,
asbestos that is friable or can be reasonably expected to become friable or
hazardous levels of urea formaldehyde foam insulation.

                           (v) For the purposes of this Lease, "Environmental
Requirements" means all applicable statutes, regulations, rules, ordinances, and
codes of all federal, state, or municipal entities, agencies, or
instrumentalities having jurisdiction over environmental matters, including
without limitation: all requirements pertaining to reporting, licensing,
permitting, investigation, and remediation of emissions, discharges, releases,
or threatened releases of Hazardous Materials, whether solid, liquid, or gaseous
in nature, into the air, surface water, groundwater or land, or relating to the
manufacture, processing, distribution, use, treatment, storage, disposal,
transport, or handling of Hazardous Materials, whether solid, liquid, or gaseous
in nature; all environmental requirements pertaining to the protection of the
health and safety of employees or the public, including but not limited to the
Hazardous Materials Transportation Act, as amended, the Resource Conservation
and Recovery Act of 1976, as amended, the Clean Air Act, as amended, the Federal
Water Pollution Control Act, as amended, the Comprehensive Environmental
Response, compensation and Liability Act of 1980, as amended, and the Toxic
Substances Control Act, as amended.

                  (e) For the purposes of this Lease, Landlord's knowledge is
limited to the actual knowledge, without independent inquiry, of Tom Miller,
Real Estate Manager for Landlord.

                  (f) Landlord warrants that all mechanical systems will be in
working condition for a period of ninety (90) days after the Commencement Date,
provided the mechanical systems are not damaged by Tenant's Improvements.

         41.      REPRESENTATIONS AND WARRANTIES OF TENANT.

                  Tenant warrants and represents to Landlord:

                  (a) Tenant, and the officer of Tenant executing this Lease,
are each duly authorized to execute and to enter into this Lease. This Lease is
a legal, binding, and valid obligation of Tenant, enforceable in accordance with
its terms.


                                       28
<PAGE>   37


                  (b) The execution and delivery of this Lease by Tenant do not
conflict with or cause a default by Tenant under any laws, rules, regulations,
or court orders of any governmental authority or any agreement or prior lease to
which Tenant is a party or by which any of its assets are bound.

         42.      HAZARDOUS MATERIALS.

                  (a) Studies. Tenant acknowledges receipt of a copy of a
Phase I Environmental Assessment of the Towers at Williams Square, Las Colinas
Urban Center, Irving, Texas, dated February 1992, prepared by Camp Dresser &
McKee, Inc., for CDM Project No.: 2053-21l-RT-REPT ("Hazardous Substance
Survey").

                  Landlord, except as provided in Paragraph 42, makes no, and
Tenant waives any, representations or warranties whatsoever to Tenant regarding:
(i) the Hazardous Substance Survey (including, without limitation, the contents,
accuracy, or adequacy of preparation thereof), or (ii) the presence or absence
of Hazardous Materials (hereinafter defined) in, at, or under the Leased
Premises or the Project.

                  (b) Landlord agrees to comply with all Environmental
Requirements pertaining to or otherwise affecting the Project and the Leased
Premises and shall not use, store, dispose of or permit to remain any Hazardous
Materials on, under, in or about the Project or the Leased Premises in amounts
or concentrations that require investigation or remedial or removal action
pursuant to any Environmental Requirements.

                  (c) Tenant shall not use, store or dispose of any Hazardous
Materials on, under, in or about the Leased Premises in amounts or
concentrations that require investigation or remedial or removal action pursuant
to any Environmental Requirements.

         43.      BUSINESS PURPOSE.

                  Tenant represents that this Lease is executed by Tenant, and
all obligations of Tenant arising out of this Lease are, primarily for business
or commercial purposes and not for personal, family, or household purposes.

         44.      SEVERABILITY.

                  Each and every covenant and agreement contained in this Lease
is, and shall be construed to be, a separate and independent covenant and
agreement. If any term or provision of this Lease or the application thereof to
any person or circumstances shall to any extent be invalid and unenforceable,
the remainder of this Lease, or the application of such term or provision to
persons or circumstances other than those as to which it is invalid or
unenforceable, shall not be affected thereby.


                                       29
<PAGE>   38


         45.      NO MERGER.

                  There shall be no merger of this Lease or of the leasehold
estate hereby created with the fee estate in the Leased Premises or any part
thereof by reason of the fact that the same person may acquire or hold, directly
or indirectly, this Lease or the leasehold estate hereby created or any interest
in this Lease or in such leasehold estate as well as the fee estate in the
Leased Premises or any interest in such fee estate.

         46.      FORCE MAJEURE.

                  Whenever a period of time is herein prescribed for action to
be taken by Landlord or Tenant (other than Tenant's obligation to pay rent), the
responsible 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, acts of God, shortages of labor or materials, war, governmental laws,
regulations, restrictions, or any other cause of any kind whatsoever which is
beyond the control of the responsible party.

         47.      BROKERAGE.

                  Tenant warrants that it has had no dealings with any broker or
agent in connection with the negotiation or execution of this Lease other than
The Staubach Company, hereinafter referred to as the "Broker", whether one or
more. Tenant and Landlord each agree to indemnify the other against all costs,
expenses, attorneys' fees or other liability for commissions or other
compensation or charges claimed by any broker or agent, other than Broker,
claiming the same by, through or under the indemnifying party with respect to
the original term hereof or any renewal or extension thereof or with respect to
any expansion of the Leased Premises. The brokerage commission payable to the
Broker, if any, shall be paid by Landlord pursuant to the terms of a separate
agreement between Landlord and the Broker. The Broker is licensed and regulated
by the Texas Real Estate Commission (the "TRECII). TREC administers two
recovery funds which may be used to satisfy judgments against inspectors and
real estate licenses involving a violation of the law. Complaints or inquiries
should be directed to the Texas Real Estate Commission, P.O. Box 12188, Austin,
Texas 78711-2188 (512) 465-3960.

         48.      GENDER.

                  Words of any gender used in this Lease shall be held and
construed to include any other gender and words in the singular number shall be
held to include the plural, unless the context otherwise requires.

         49.      JOINT AND SEVERAL LIABILITY.

                  If there be more than one Tenant, the obligations hereunder
imposed upon Tenant shall be joint and several.


                                       30
<PAGE>   39


         50.      NO REPRESENTATIONS.

                  Landlord or Landlord's agents have made no representations or
promises with respect to the Leased Premises, the Building or the Land except as
herein expressly set forth and no rights, easements, or licenses are acquired by
Tenant by implication or otherwise except as expressly set forth in the
provisions of this Lease.

         51.      ENTIRE AGREEMENT.

                  This Lease sets forth the entire agreement between the parties
and no amendment or modification of this Lease shall be binding or valid unless
expressed in a writing executed by both parties hereto.

         52.      PARAGRAPH HEADINGS.

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

         53.      BINDING EFFECT.

                  All of the covenants, agreements, terms, and conditions to be
observed and performed by the parties hereto shall be applicable to and binding
upon their respective heirs, personal representatives, successors, and, to the
extent assignment is permitted hereunder, their respective assigns.

         54.      RENTAL TAX.

                  Notwithstanding any other provision herein contained, Tenant
shall pay any and all licenses, charges, and other fees of every kind and nature
as and when they become due and before the same become delinquent arising out of
or in connection with the Tenant's use and occupancy of the Leased Premises,
including but not limited to license fees, business license tax, the amount of
any privilege, sales, excise, or other similar tax (other than income and
franchise taxes) imposed upon Rent herein provided to be paid by Tenant or upon
the Landlord in an amount measured by such Rent received by Landlord.

         55.      PARKING.

                  (a) At no additional cost to Tenant, Landlord agrees to
provide, and Tenant agrees to rent, throughout Lease Term, three (3) reserved
spaces and seventy-eight (78) unreserved spaces for the parking of automobiles
in the West Tower parking garage located at the Building, as set forth in this
paragraph; provided, however, if for any reason Landlord fails or is unable to
provide parking space to Tenant or Tenant is not permitted to use parking space
in such parking garage for all or any of such automobiles at any time during the
Lease Term, such failure or inability shall not constitute a default by Landlord
under this Lease. With respect to the unreserved parking spaces, Tenant shall
not be assigned to designated parking spaces, but

                                                                 [INITIAL STAMP]


                                       31
<PAGE>   40


shall be permitted to use whatever stalls are available, on a first-come,
first-served basis, in areas of the parking garage designated by Landlord.

                  (b) Landlord will cause Master Landlord to issue to Tenant
eighty (80) magnetic parking cards for access to the leased parking spaces
provided that Tenant provides Master Landlord with the license numbers of the
automobiles of Tenant's employees who will be using such cards and the
understanding that no more than two (2) reserved and seventy-eight (78)
unreserved spaces shall be used by Tenant and its employees at one time. In the
event Tenant uses more than two (2) reserved and seventy-eight (78) unreserved
spaces Landlord or Master Landlord may at any time call in or void any extra
issued magnetic parking cards. Upon receipt of any notice of any call of such
cards, Tenant shall immediately surrender same.

                  (c) Tenant shall comply with all traffic, security, safety and
other rules and regulations promulgated from time to time by the operator of the
garage.

         56.      BUILDING ACCESS.

                  Tenant shall have unlimited access to the Premises twenty-four
(24) hours per day, seven (7) days per week. If, at any time, the Leased
Premises lack utilities for three consecutive business days in any twelve month
period, then rent and additional rent shall abate proportionately to the extent
the Premises are untenantable by reason thereof. If the lack continues for a
period in excess of sixty (60) consecutive days during any twelve month period,
then Tenant shall have the right to terminate the Sublease.

         57.      SEVERABILITY.

                  If any term or provision of this Lease or the application
thereof to any person or circumstances shall to any extent be invalid and
unenforceable, the remainder of this Lease, or the application of such term or
provision to persons or circumstances other than those as to which it is invalid
or unenforceable, shall not be affected thereby.

         58.      DISCLAIMER OF WARRANTIES.

                  TENANT ACKNOWLEDGES THAT IT HAS INSPECTED THE LEASED PREMISES
AND IS THOROUGHLY FAMILIAR WITH ITS CONDITION. TENANT ACCEPTS THE LEASED
PREMISES IN ITS PRESENT CONDITION (SAVE AND EXCEPT LATENT DEFECTS, INCLUDING
STRUCTURAL DEFECTS) AND ACKNOWLEDGES ANY AGREES THAT LANDLORD HAS NOT MADE AND
DOES NOT HEREBY MAKE ANY REPRESENTATIONS, WARRANTIES OR COVENANTS OF ANY KIND OR
CHARACTER EXPRESS OR IMPLIED WITH RESPECT TO THE LEASED PREMISES, INCLUDING, BUT
NOT LIMITED TO, WARRANTIES OR REPRESENTATIONS AS TO MATTERS OF TITLE (OTHER THAN
AS EXPRESSLY MADE BY LANDLORD HEREIN), ZONING, TAX CONSEQUENCES, PHYSICAL OR
ENVIRONMENTAL CONDITIONS, AVAILABILITY OF ACCESS, INGRESS OR EGRESS, OPERATING
HISTORY OR PROJECTIONS, VALUATION, GOVERNMENTAL APPROVALS, GOVERNMENTAL
REGULATIONS, OR THE ADEQUACY OF ANY EQUIPMENT IN THE LEASED


                                       32
<PAGE>   41
PREMISES TO MEET THE PARTICULAR NEEDS OF TENANT AND TENANT EXPRESSLY DISCLAIMS
ANY IMPLIED WARRANTY THAT THE LEASED PREMISES ARE SUITABLE FOR TENANT IS
INTENDED COMMERCIAL PURPOSES OR ANY OTHER MATTER OR THING RELATING TO OR
AFFECTING THE LEASED PREMISES INCLUDING, WITHOUT LIMITATION: (A) THE VALUE,
CONDITION, MERCHANTABILITY, MARKETABILITY, PROFITABILITY, SUITABILITY OR FITNESS
FOR A PARTICULAR USE OR PURPOSE OF THE LEASED PREMISES, (B) THE MANNER OR
QUALITY OF THE CONSTRUCTION OR MATERIALS INCORPORATED INTO ANY OF THE LEASED
PREMISES AND (C) THE QUALITY, STATE OF REPAIR OR LACK OF REPAIR OF THE LEASED
PREMISES. TENANT AGREES THAT WITH RESPECT TO THE LEASED PREMISES, TENANT HAS NOT
RELIED UPON AND WILL NOT RELY UPON, EITHER DIRECTLY OR INDIRECTLY, ANY
REPRESENTATION OR WARRANTY OF LANDLORD OR ANY AGENT OF LANDLORD EXCEPT AS
EXPRESSLY MADE BY LANDLORD IN THIS LEASE.

         59.      WORK ALLOWANCE.

                  Landlord shall allow Tenant access to the Leased Premises
commencing on the later of the date this Lease is executed and the date this
Lease is approved by Master Landlord, for the purpose of constructing Tenant's
improvements (the "Improvements") to the Leased Premises. All Tenant
Improvements shall be constructed pursuant to plans and specifications therefor
approved in writing by Landlord (the "Tenant Plans"). Tenant agrees to construct
the Tenant Improvements in accordance with the Tenant Plans. Tenant shall pay
all costs of constructing all Tenant Improvements.

         60.      APPROVALS BY MASTER LANDLORD.

                  Whenever in this Lease the Tenant will be required to obtain
the consent or approval of Landlord with respect to any matter, and in the
reasonable judgment of Landlord, would also require the consent or approval of
the Master Landlord, then in the sole discretion of Landlord, the consent or
approval of both Landlord and Master Landlord must be obtained prior to the
taking of any action by Tenant; provided, however, if Master Landlord consents
to or approves such matter, Landlord will not unreasonably withhold or delay its
consent or approval.

         61.      COUNTERPARTS.

                  This Lease may be executed in two or more counterparts, each
of which shall be deemed an original, but all of which together shall constitute
one and the same instrument.

         62.      JANITOR SERVICE

                  Tenant may elect to provide its own janitor and maid service
for the Leased Premises by giving not less than 60 days' prior notice to
Landlord and Master Landlord. If Tenant provides its own janitor and maid
service, the services provided must be at least equal in scope to Master
Landlord's standard janitorial and maid service. If Tenant elects to provide its
own janitor and maid service for the Leased Premises, it may subsequently elect
to require


                                       33
<PAGE>   42


Landlord to resume providing Master Landlord's standard janitorial and maid
service by giving not less than 60 days' prior notice to Landlord and Master
Landlord. Tenant may not exercise this option to provide its own janitorial
service more than once during the Lease Term.

                  IN WITNESS WHEREOF, this Lease is hereby executed in multiple
originals as of the day and year first above set forth.


                                        LANDLORD:

                                        TIG Insurance Company, a California
                                        corporation


                                        By:  /s/ L. P. MCCLIMON
                                             -----------------------------------
                                        Name: L. P. McClimon
                                              ----------------------------------
                                        Title: Managing Director
                                               ---------------------------------


                                        By:  /s/ THOMAS J. MILLER
                                             -----------------------------------
                                        Name: Thomas J. Miller
                                              ----------------------------------
                                        Title: Director -- Administration
                                               ---------------------------------

                                        TENANT

                                        Advance Paradigm, Inc., a Delaware
                                        corporation


                                        [INITIAL STAMP]


                                        By:  /s/ JON S. HALBERT
                                             -----------------------------------
                                        Name: John S. Halbert
                                              ----------------------------------
                                        Title: EVP & COO
                                              ----------------------------------


                                       34
<PAGE>   43


                                    Exhibit A


                         Floor Plan of Leased Premises




EXHIBIT A - SOLO PAGE


<PAGE>   44


                                    EXHIBIT B

                                LEGAL DESCRIPTION

Being a tract or parcel of land situated in the City of Irving, Dallas County,
Texas; and being a part of the Elizabeth Crockett Survey, Abstract No. 217; and
being all of Lot 1, Las Colinas Urban Center, Installment 12, an addition to the
City of Irving, as recorded in Volume 81077, Page 3167 of the Map and Deed
Records of Dallas County, Texas.




EXHIBIT B - SOLO PAGE

<PAGE>   45


                                    EXHIBIT C

                          OPERATING EXPENSE EXCLUSIONS

The definition of "Operating Costs" in the Lease shall expressly exclude the
following:

1.       Costs of repair or replacement or other work occasioned by exercise of
         the right of eminent domain.

2.       Leasing commissions, advertising and other promotional costs and
         expenses, attorneys' fees, costs and disbursements and other expenses
         incurred in negotiating or executing leases or in resolving disputes
         with other tenants, other occupants, or other prospective tenants or
         occupants of the Project, collecting rents or otherwise enforcing
         leases of other tenants of the Project.

3.       Costs and expenses of special services rendered to particular tenants
         of the Project or that exclusively benefit another tenant or tenants of
         the Project, including, without limitation, costs of tenant
         installations, decorating expenses, redecorating expenses, or
         constructing improvements or alterations to any tenant space; the costs
         of any janitorial cleaning service or security services provided to
         other tenants which exceed the standard of that provided to Tenant; and
         costs in connection with services (including electricity), items or
         other benefits of a type which are not standard for the Project and
         which are not available to Tenant without specific charge therefor, but
         which are provided to another tenant or occupant of the Project,
         whether or not such other tenant or occupant is actually charged
         therefor by Landlord.

4.       Except for the amortization of the cost of capital items which are
         primarily for the purpose of reducing operating expenses of the
         Project, Operating Costs shall include no costs or expenditures that
         would be classified as a capital expense under generally accepted
         accounting principles consistently applied. All such capital
         expenditures shall be amortized over the useful life of the capital
         improvement, as determined in accordance with generally accepted
         accounting principles consistently applied, but in no event to extend
         beyond the reasonable life of the Project. The amount to be included in
         Operating Costs shall be the lesser of (a) the amortized amount,
         determined in accordance with the foregoing, or (b) the actual
         reduction in operating Costs resulting from the capital improvement
         during the same calendar year. Operating Costs shall not include
         capital costs of complying with the Americans with Disabilities Act; or
         the Texas Architectural Barriers Act (collectively, the "Acts").

5.       Depreciation, amortization and other non-cash items except as otherwise
         provided herein.

6.       Costs and expenses incurred by Landlord for which Landlord is actually
         reimbursed by parties other than tenants of the Project, including,
         without limitation, insurance proceeds.

7.       Costs and expenses attributable to the initial construction of the
         Project (including correcting structural construction defects).


EXHIBIT C -- PAGE 1

<PAGE>   46


8.       Except for the management fee, any overhead or profit increment to any
         subsidiary or affiliate of Landlord for services on or to the building,
         parking garage or related facilities and/or the land on which the
         building is situated, to the extent that the cost of such services
         exceeds the competitive costs for such services rendered by persons or
         entities of similar skill, competence and experience other than a
         subsidiary of affiliate of Landlord.

9.       Finance and debt service fees; principal and/or interest on debt or
         amortization payments on any mortgage or mortgages executed by Landlord
         covering Landlord's Property; and rental under any ground or underlying
         lease or leases for the Project.

10.      Landlord's general overhead except as it directly relates to the
         operation, management, maintenance, repair and security of the Project.

11.      Any compensation paid to clerks, attendants or other persons in
         commercial concessions operated by Landlord.

12.      Costs and expenses for items and services for which Tenant reimburses
         Landlord or pays third persons, to the extent of such reimbursement or
         payment.

13.      Costs including fines, penalties, and legal fees incurred due to
         violations by Landlord, its employees, agents, contractors or assigns,
         or any other tenant or occupant of the Project, of building codes, any
         other governmental rule or requirement or the terms and conditions of
         any lease pertaining to the Project.

14.      Costs of management fees to the extent they exceed comparable fees
         incurred in comparable Class A office buildings in the Dallas-Fort
         Worth metropolitan area.

15.      Costs of sculptures, paintings, wall hangings or other objects of art,
         including, without limitation, costs incurred with respect to the
         purchase, ownership, leasing, repair and/or maintenance of same.

16.      Costs of wages, salaries, or other compensation paid to any executive
         employees of Landlord above the grade of project manager or paid to
         employees of Landlord who are not employed full time, on site at the
         office project; provided, further, if any employee of Landlord works on
         several buildings within the area, including the Project, the costs and
         expenses connected with such employee shall be allocated among such
         buildings by Landlord in accordance with reasonable and consistent
         criteria.

17.      Costs and expenses incurred in leasing air-conditioning systems,
         elevators, or other equipment ordinarily considered to be of a capital
         nature.

18.      Costs and expenses associated with the removal or encapsulation of
         asbestos or other hazardous or toxic substances.

19.      Any costs or expenses incurred in compliance with new or revised
         federal or state laws or


EXHIBIT C -- PAGE 2


<PAGE>   47


         municipal ordinances, or codes or regulations promulgated under any of
         the same, requiring modification only to any areas of the Project
         leased to any tenant, including Tenant.

20.      Any expenses for repairs or maintenance which are covered by warranties
         and service contracts, to the extent such maintenance and repairs are
         made at no cost to Landlord.

21.      Any costs representing any amount paid for services and materials to a
         related person, firm, or entity to the extent such amount exceeds the
         amount that would be paid for such services or materials at the then
         existing market rates to an unrelated person, firm or corporation.

22.      If any taxes paid by Landlord and previously included in Operating
         Costs are refunded, Landlord shall promptly pay Tenant an amount equal
         to the amount of such refund (less the out-of-pocket expenses incurred
         by Landlord in obtaining such refund) multiplied by Tenant's
         Proportionate Share in effect for the period to which such refund
         relates.

23.      The cost of curing any of Landlord's Events of Defaults.

24.      Any amounts payable by Landlord by way of indemnity or for damages or
         which constitutes a fine or penalty, including interest or penalties
         for any late payment.

25.      Repairs necessitated by violations of law in effect as of the date of
         the Lease.

26.      Repairs and alterations necessitated by the negligence or willful
         misconduct or Landlord or its agents, employees, or contractors or
         repairs and alterations necessitated by the negligence or willful
         misconduct of any tenant or occupant of the Project, including Tenant,
         or of any of their respective agents, employees, contractors, invitees,
         or licensees.

27.      Property taxes and assessments which are not properly allocable to the
         Project. Without limiting the generality of the foregoing, property
         taxes and assessments which are properly allocable to undeveloped land
         shall be excluded from Operating Costs.

28.      Any costs incurred in installment, operating, maintaining and owning
         any specialty not used by Tenant and not normally installed, operated
         and maintained in Class A office buildings comparable to the Project
         and not necessary for Landlord's operation, repair, maintenance, and
         providing of required services for the Project and/or any associated
         parking facilities, including, but not limited to, an observatory,
         antenna or antennae, beacon(s), broadcasting facilities (other than the
         Project's music system and life support and security systems), luncheon
         club, cafeteria, athletic or recreational club, helicopter pad, etc.

29.      The costs of any additional casualty insurance premium for the Project
         in excess of the standard rate payable by Landlord.

30.      Interest and penalties due to the late payment of taxes, utility bills
         or other such costs


EXHIBIT C -- PAGE 3


<PAGE>   48


         except any interest or penalties arising from late payments beyond
         Landlord's control.

31.      Any other expenses which, under generally accepted accounting
         principles, consistently applied, would not be considered to be a
         normal maintenance or operating expenses of the Project including,
         without limitation, bad debt expenses and charitable contributions and
         donations.


EXHIBIT C -- PAGE 4


<PAGE>   49


                                    EXHIBIT D

                         SCHEDULE OF JANITORIAL SERVICES


A.       OFFICE AREAS

         1.       Empty, clean and damp dust all waste receptacles and remove
                  waste paper and rubbish from the Leased Premises nightly; wash
                  receptacles as necessary.

         2.       Empty and clean all ash trays, screen all sand urns nightly,
                  and supply and replace as necessary.

         3.       Vacuum all rugs and carpeted areas in offices, lobbies and
                  corridors nightly.

         4.       Hand dust and wipe clean with damp or treated cloth all office
                  furniture, files, fixtures, paneling, window sills and all
                  other horizontal surfaces nightly; wash window sills when
                  necessary.

         5.       Damp wipe and polish all glass furniture tops nightly.

         6.       Remove all finger marks and smudges from vertical surfaces,
                  including doors, door frames, around light switches, private
                  entrance glass and partitions nightly.

         7.       Wash clean all water coolers nightly.

         8.       Sweep all stairways nightly; vacuum if carpeted.

         9.       Police all stairwells throughout the entire Buildings daily
                  and keep in clean condition.

         10.      Damp mop spillage in office and public areas as required.

         11.      Damp dust all telephones as necessary.

B.       WASH ROOMS

         1.       Mop, rinse and dry floors nightly.

         2.       Scrub floors as necessary.

         3.       Clean all mirrors, bright work and enameled surfaces nightly.

         4.       Wash and disinfect all basins, urinals and bowls nightly,
                  using non-abrasive cleaners to remove stains and clean
                  undersides of rim of urinals and bowls.


EXHIBIT D -- PAGE 1


<PAGE>   50


         5.       Wash both sides of all toilet seats with soap and water and
                  disinfect nightly.

         6.       Damp wipe nightly, wash all partitions, tile walls and outside
                  surface of all dispensers and receptacles.

         7.       Empty and sanitize all receptacles and sanitary disposals
                  nightly; thoroughly clean and wash at least once per week.

         8.       Fill toilet tissue, soap, towel and sanitary napkins
                  dispensers nightly.

         9.       Clean flushmeters, piping, toilet seat hinges and other metal
                  work nightly.

         10.      Wash and polish all walls, partitions, tile walls and enamel
                  surfaces from trim to floor monthly.

         11.      Apply finish to tile floor when necessary as instructed by the
                  Buildings management.

         12.      Vacuum all louvers, ventilating grills, and dust light
                  fixtures monthly.

NOTE: It is the intention to keep the washrooms thoroughly cleaned and not use a
disinfectant or deodorant to kill odor. If a disinfectant is necessary, an
odorless product will be used with the Tenant's permission.

C.       FLOORS

         1.       Ceramic tile, marble and terrazzo floors to be swept and
                  buffed nightly and washed or scrubbed as necessary.

         2.       Asphalt, vinyl, rubber or other composition floors and bases
                  to be swept nightly; such floors in public areas on multiple
                  tenancy floors to be waxed and buffed as needed.

         4.       All floors stripped and rewaxed as necessary.

         5.       All carpeted areas and rugs to be vacuumed clean nightly.

         6.       Carpet shampooing will be performed at Tenant's request and
                  billed by Landlord.

D.       GLASS

         1.       Clean glass entrance doors and adjacent glass panels nightly.

E.       HIGH DUSTING (Quarterly)

         1.       Dust and wipe clean all closet shelving when empty and carpet
                  sweep or dry mop all floors in closets if such are empty.


EXHIBIT D -- PAGE 2


<PAGE>   51



         2.       Dust all picture frames, charts, graphs and similar wall
                  hangings.

         3.       Dust clean all vertical surfaces such as walls, partitions,
                  doors, door backs and other surfaces above shoulder height.

         4.       Damp dust all ceiling air conditioning diffusers, wall
                  grilles, registers and other ventilating louvers.

         5.       Dust the exterior surfaces of lighting fixtures, including
                  glass and plastic enclosures.

F.       DAY SERVICE

         1.       At least once, and more as deemed necessary during the day,
                  check men's washrooms for toilet tissue replacement.

         2.       At least once, and more as deemed necessary during the day,
                  check ladies' washrooms and toilet tissue and sanitary napkin
                  replacement.

         3.       Supply toilet tissue, soap and towels in men's and ladies'
                  washrooms and sanitary napkins in ladies' washrooms.

         4.       As needed, vacuuming of elevator cabs will be performed.

         5.       There will be a constant surveillance of public areas to
                  ensure cleanliness.

         6.       Clean ash urns as necessary in elevator lobbies.

         7.       Clean Buildings glass entrance doors and panels as needed.

G.       GENERAL

         1.       At intervals of no more than one (1) year and more often if
                  required by the Buildings' management, thoroughly wash and dry
                  the interior of all windows, including wiping all interior
                  metal window frames, mullions, and other unpainted interior
                  metal surfaces of the perimeter walls of the Buildings each
                  time the interior of the windows is washed.

         2.       Keep janitorial closets in a clean, neat and orderly condition
                  at all times.

         3.       Wipe clean and polish all metal hardware fixtures and other
                  bright work nightly.

         4.       Dust and/or wash all directory boards as required, remove
                  fingerprint and smudges nightly.

         5.       Maintain Buildings lobby, corridors, elevators and other
                  public areas in a clean condition.


EXHIBIT D -- PAGE 3


<PAGE>   52


         6.       Dust fire extinguisher and cabinets nightly (interior and
                  exterior); wash as necessary.

         7.       All baseboards (resilient flooring and carpeting areas) will
                  be washed and wiped clean as necessary.

         8.       Vacuum entrance mats nightly.

         9.       Hose and scrub plaza area and sidewalks as necessary.

         10.      Perform special cleaning needs of individual tenants as
                  authorized and directed by the Buildings management.

         11.      Properly maintain exterior of Buildings at ground level by
                  ensuring that curtain wall, glass, marble, etc., is kept in a
                  clean condition. Exterior stainless steel is to be cleaned and
                  polished weekly.

         12.      Polish standpipes and sprinkler Siamese connections as
                  necessary.

NOTE: Upon completion of nightly duties, floor supervisors will ensure that all
offices have been cleaned and left in a neat and orderly condition and that all
lights have been turned off and all doors locked.


EXHIBIT D -- PAGE 4


<PAGE>   53


                                    EXHIBIT E

                         BUILDING RULES AND REGULATIONS




                  to office Lease by and between T-Las Colinas Towers Corp. and
Transamerica Insurance Company, a California corporation.

                         BUILDINGS RULES AND REGULATIONS

                  1. Except for guide dogs and other animals trained to assist
persons who are physically disabled, no birds, animals, reptiles, or any other
creatures, $hall be brought into or about the Buildings.

                  2. Nothing shall be swept or thrown into the corridors, halls,
elevator shafts or stairways.

                  3. Tenant shall not create a nuisance in the Project.

                  4. No equipment of any kind shall be operated an the Leased
Premises that could in any way annoy any other tenant in the Project without the
prior written consent of Landlord.

                  5. Tenant shall cooperate with the Project employees in
keeping the Leased Premises neat and clean.

                  6. Corridor doors on multi-tenant floors, when not in use,
shall be kept closed.

                  7. No bicycles or similar vehicles will be allowed in the
Buildings.

                  8. Tenant will refer all contractors, contractor's
representatives, and installation technicians rendering any service on or to the
Leased Premises or elsewhere in the Project for Tenant to Landlord, for
Landlord's approval and supervision for performance of any contractual service.
This provision shall apply to all work performed in the Project, including
installation of telephones, telegraph equipment, electrical devices, and
attachments and installations of any nature affecting floors, walls, woodwork,
trim, windows, ceiling, equipment, or any other physical portion of the Project.

                  9. Except for use in hanging artwork, diplomas, certificates,
and similar standard office furnishings, no nails, hooks, or screws shall be
driven into or inserted in any part of the project except by Project maintenance
personnel.

                  10. Sidewalks, doorways, vestibules, halls, stairways, and
similar areas shall not be obstructed by Tenant or its agents, employees or
contractors or used for any purpose other


EXHIBIT E -- PAGE 1


<PAGE>   54


than ingress and egress to and from the Leased Premises, or for going from one
part of the Buildings to another part of the Buildings. No furniture shall be
placed in front of the Buildings, or in any lobby or corridor without written
consent of Landlord.

                  11. Tenant, its employees, or agents, or anyone else who
desires to enter the Buildings after Normal Business Hours, will be required to
sign in upon entry and sign out upon leaving, giving the location during their
stay and their time of arrival and departure.

                  12. All deliveries must be made via the service entrance and
service elevator, when provided during normal working hours or at such times as
Landlord may determine. Prior approval must be obtained from the Landlord for
all deliveries that must be received after normal working hours.

                  13. Landlord or its agents or employees shall have the right
to enter the Leased Premises to examine the same or to make such repairs,
alterations, or additions as Landlord shall deem necessary for the safety,
preservation, or improvement of the Buildings.

                  14. Landlord has the right to evacuate the Buildings in the
event of an emergency or catastrophe.

                  15. Tenant shall not do anything, or permit anything to-be
done, in or about the Project, or bring to keep anything therein, that will in
any way increase the possibility of fire or other casualty, or do anything in
conflict with the valid laws, rules, or regulations of any governmental
authority.

                  16. Tenant shall notify the Building Manager when safes or
other equipment are to be taken into or out of the Project. Moving of such items
shall be done under the supervision of the Building Manager, after receiving
written permission from him.

                  17. Landlord shall have the power to prescribe the weight and
position of safes or other heavy equipment, which may overstress any portion of
the floor. All damage done to the Buildings by the improper placing of heavy
items which overstress the floor will be repaired at the sole expense of the
Tenant.

                  18. No food shall be distributed from Tenant's office without
the prior written approval of the Building Manager.

                  19. No additional locks shall be placed upon any doors without
the prior written consent of Landlord. All necessary keys shall be furnished by
Landlord, and the same shall be surrendered upon termination of this lease, and
Tenant shall then give Landlord or his agent an explanation of the combination
of all locks on the doors and vaults.

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

                  21. Plumbing and appliances shall be used only for the
purposes for which


EXHIBIT E -- PAGE 2


<PAGE>   55


constructed, and no sweeping, rubbish, rags, or other unsuitable material shall
be thrown or placed therein. Any stoppage or damage resulting to any such
fixtures or appliances from misuse on the part of Tenant or Tenant's officers,
agents, servants, and employees shall be paid by Tenant.

                  22. No signs, posters, advertisements, or notices shall be
painted or affixed on any of the windows or doors, or other parts of the
Project, except in such color, size, and style, and in such places, as shall be
first approved in writing by Landlord. Building standard suite identification
signs will be prepared by a sign writer, approved by Landlord. The cost of the
Building Standard sign will be paid by Tenant. Landlord shall have the right to
remove all unapproved signs without notice to Tenant, at the expense of Tenant.
Directories will be placed by Landlord at Landlord's own expense, in conspicuous
places in the Buildings. No other directories shall be permitted.

                  23. No portion of the Buildings shall be used for the purpose
for lodging rooms or any immoral or unlawful purposes.

                  24. Tenant shall not operate, or allow the operation of,
without the prior written consent of Landlord, any coin or token operated
vending machine or similar device for the sale of any goods, wares, merchandise,
food, beverages, or services, including but not limited to pay lockers, pay
toilets, scales, amusement devices and machines for the sale of beverages,
foods, candy, cigarettes or other commodities.

                  25. Prior written approval, which shall be at Landlord's sole
discretion, must be obtained for installation of any solar screen material,
window shades, blinds, drapes, awnings, window ventilators, or other similar
equipment and any window treatment of any kind whatsoever. Landlord will control
all internal lighting that may be visible from the exterior of the Buildings and
shall have the right to change any unapproved lighting, without notice to
Tenant, at Tenant's expense.

                  26. Landlord reserves the right to rescind any of these rules
and make such other future rules and regulations as in the judgment of Landlord
shall from time to time be needed for the safety, protection, care, and
cleanliness of the Project, the operation thereof, the preservation of good
order therein, and the protection and comfort of its tenants, their agents,
employees, and invitees, which rules when made and notice thereof given to a
tenant, shall be binding upon him in like manner as if originally herein
prescribed.

                  27. Tenant shall at all times keep a chair pad under every
chair which has rollers and is located in a carpeted area.

                  28. Tenant shall not permit any of its employees, invitees,
agents, servants, licensees, clients, or visitors to hold, carry, smoke, or
dispose of a lighted cigar, cigarette, pipe, or any other lighted smoking
equipment in any common area of the Project. The common areas shall include, but
not be limited to all rest rooms, common corridors, stairwells, elevator
lobbies, first floor lobbies, and other areas used in common with other tenants
and occupants of the Project.


EXHIBIT E -- PAGE 3
<PAGE>   56

                                    EXHIBIT F



             SUBORDINATION, NON-DISTURBANCE AND ATTORNMENT AGREEMENT



         THIS AGREEMENT is entered into this ___________day of ________, 1999,
by ("Tenant"), and ______________________,a ________________ corporation
("Lender").

                                   BACKGROUND

         A. TIG INSURANCE COMPANY ("Sublandlord") is the lessee under an
Agreement of Lease dated October 4, 1993 (the "Master Lease"), between
Sublandlord and T-Las Colinas Towers Corp. ("Borrower"), as Landlord, covering
the leased premises located in the Williams Square complex in the City of
Irving, Dallas County, Texas, more fully described in Exhibit A attached to this
Agreement (the "Premises").

         B. Sublandlord has subleased a portion of such premises to Tenant under
an Agreement of Lease dated ___________, 1995 (the "Lease").

         C. Borrower has a mortgage loan from Lender secured by a deed of trust
from __________________ to Lender (the "Mortgage") covering, among other
property, the Premises.

         D. Lender and Tenant agree that it is in each party's best interest to
enter into this Agreement and for Tenant to enter into the Lease.

                                    AGREEMENT

         In consideration of the mutual covenants and agreements in this
Agreement, and to induce Tenant to enter into the Lease, Tenant and Lender agree
as follows:

         1. The Lease and the estate conveyed thereby are and shall at all times
continue to be subject and subordinate in all respects to the Mortgage and to
all renewals, modifications and extensions thereof, subject to the terms of this
Agreement.

         2. So long as Tenant is not in default (beyond any period given Tenant
to cure the default) in the payment of rent or additional rent or in the
performance of any of the other terms, covenants, or conditions of the Lease on
Tenant's part to be performed, Tenant's possession under the Lease and Tenant's
rights and privileges thereunder or under any extensions or renewals thereof,
which may be affected in accordance with any option therefor contained in the
Lease, may not be diminished or interfered with by Lender under any
circumstances, and Tenant's occupancy may not be disturbed by Lender during the
term of the Lease or any extensions or renewals thereof. Lender will be bound by
the terms of the Lease and may not join Tenant as a party defendant in any
foreclosure proceedings taken by Lender.



EXHIBIT E -- PAGE 4



<PAGE>   57
         3. If the interests of Borrower are acquired by Lender by reason of
foreclosure of the Mortgage or any other proceedings brought to enforce the
rights of the holder of the Mortgage, by deed in lieu of foreclosure or by any
other method, and Lender succeeds to the interests of Borrower under the Lease,
the Lease and the rights of Tenant thereunder continue in full force and effect
and may not be terminated or disturbed except in accordance with the terms of
the Lease. Tenant is bound to Lender under all the terms, covenants, and
conditions of the Lease for the balance of the term thereof remaining and any
extensions or renewals thereof, which may be effected in accordance with any
option therefor contained in the Lease, with the same force and effect as if
Lender were the lessor under the Lease, and Tenant does hereby attorn to Lender,
as its lessor, the attornment to be effective and self-operative without the
execution of any other instruments on the part of either party hereto,
immediately upon Lender's succeeding to the interest of Borrower under the
Lease; provided, however, that Tenant is under no obligation to pay rent to
Lender until Tenant receives written notice from Lender that Lender has
succeeded to the interests of Borrower under the Lease. The respective rights
and obligations of Tenant and Lender upon the attornment, to the extent of the
then remaining balance of the term of the Lease and any extensions or renewals
are the same as now set forth in the Lease; it being the intention of the
parties hereto for this purpose to incorporate the Lease into this Agreement by
reference, with the same force and effect as if set forth at length herein.

         4. This Agreement may not be modified orally or in any other manner
other than by an agreement in writing signed by the parties hereto or their
respective successors in interest. Tenant shall send to Lender, at the following
address, copies of all notices given to Sublandlord pursuant to the terms of the
aforesaid Lease at the same time the notice is given to Sublandlord:

                TIG INSURANCE COMPANY
                5205 N. O'Connor Boulevard
                Suite N1642
                Irving, Texas 75039

         5. This Agreement inures to the benefit of and is binding upon the
parties hereto, their respective heirs, successors, and assigns; it being
expressly understood that all references herein to Lender are deemed to include
not only Lender, but also its successors and assigns.

                                 TENANT

                                 ----------------------------------------------,
                                 a
                                  ----------------------------------------------

                                 By:
                                     -------------------------------------------

                                 Name:
                                      ------------------------------------------

                                 Title:
                                        ----------------------------------------



EXHIBIT E -- PAGE 5



<PAGE>   58



                                 LENDER:

                                 ----------------------------------------------,
                                 a
                                  ---------------------------------------------

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


EXHIBIT E -- PAGE 6



<PAGE>   59



                               CONSENT TO SUBLEASE

                  This Consent to Sublease (this Consent) is made as of December
         20, 1999, by TIAA Realty, Inc., a Delaware corporation (Landlord), TIG
         INSURANCE COMPANY, a California corporation (Tenant), and ADVANCE
         PARADIGM, INC., a Delaware corporation (Subtenant).

                                   BACKGROUND

A.       By Office Lease (as amended from time to time, the "Master Lease")
         dated October 4, 1993, Landlord's predecessor in interest leased to
         Tenant space on floors 2-12, inclusive in the West Tower, floors 10-14,
         inclusive, in the East Tower, floor 16 in the Central Tower, and Suite
         900 of floor 9 in the East Tower in the Towers At Williams Square, at
         5205, 5215, and 5221 N. O'Connor Blvd., Irving, Dallas County, Texas
         75039 (the Leased Premises), as more particularly described in the
         Master Lease.

B.       The Master Lease was amended on numerous occasions.

C.       Tenant and Subtenant requested that Landlord consent to the sublease of
         a portion of the Leased Premises by Tenant to Subtenant and Landlord is
         willing to consent under the terms of this Consent.

                                     CONSENT

         Landlord, Tenant, and Subtenant agree as follows:

1.       Consent to Sublease

         Landlord consents to Tenant subletting the Sublet Premises (defined
         below) to Subtenant under the terms of the Sublease from Tenant to
         Subtenant dated 12-16-99, 1999 (the Sublease), subject to the terms of
         this Consent. A complete copy of the Sublease is attached to this
         Consent as Schedule 1. This Consent is not assignable. The portion of
         the Leased Premises being sublet to Subtenant is the 16th floor of the
         Central Tower and is referred to in this consent as the Sublet
         Premises.

2.       No Waiver or Modification.

         Nothing in this Consent:

         a.       Is an acceptance or ratification by Landlord of the terms of
                  the Sublease, or a representation or warranty of any kind by
                  Landlord relating to the Sublease or the Sublet Premises.

         b.       Except as specified in this Consent, modifies, waives, or
                  affects the Master Lease in any way.

         c.       Waives any present or future breach or default by Tenant under
                  the Master Lease.



CONSENT TO SUBLEASE -- 16TH FLOOR                                              1



<PAGE>   60




         d.       Creates any direct contractual rights between Landlord and
                  Subtenant, except under this consent, or gives Subtenant any
                  rights relating to the Master Lease, including, without
                  limitation, the right to approve any subsequent modification
                  of the Master Lease.

         The Sublease is subject and subordinate to the Master Lease. If there
         is a conflict between the Master Lease and the Sublease the Master
         Lease prevails, unaffected by any conflict with the Sublease. If there
         is a conflict between this Consent and the Sublease, this Consent
         prevails, unaffected by any conflict with the Sublease.

3.       No Release of Tenant.

         a.       Nothing in this Consent or the Sublease releases or discharges
                  Tenant from any obligation or liability payable or performable
                  by Tenant under the Master Lease. Tenant remains primarily
                  liable under the Master Lease.

         b.       Landlord is not bound or estopped in any way by the Sublease
                  or any actions of Tenant or Subtenant related to the Sublease.

         c.       Subtenant is not considered to be a Debtor as defined in
                  Section 9.105 of the Texas business and Commerce Code.

4.       Payment of Rent.

         If an Event of Default by Tenant (as defined in the Master Lease)
         relating to the payment of rent under the Master Lease occurs and is
         continuing, Landlord may, in its sole discretion, give notice (a Tenant
         Default Notice) to Subtenant requiring that Subtenant make all rent
         payments under the Sublease direct to Landlord. If Landlord gives a
         Tenant Default Notice to Subtenant, Subtenant shall pay all rent
         payable under the Sublease after Subtenant's receipt of the Tenant
         Default Notice direct to Landlord until Landlord notifies Subtenant
         that the Event of Default by Tenant has been cured. All rent
         attributable to the Sublease received by Landlord shall be applied
         against amounts owing by Tenant under the Master Lease and any excess
         rent received by Landlord from Subtenant over the aggregate amounts
         owing by Tenant under the Master Lease shall be paid by Landlord to
         Tenant within 20 days after Landlord's receipt thereof. No such direct
         payment of rent by Subtenant to Landlord is a default by Subtenant
         under the Sublease.

5.       No Further Consent.


         This Consent is not, and may not be construed to be, a consent by
         Landlord to other or further assignment or sublease of the Master Lease
         except as provided below. The Master Lease may not be further assigned
         or sublet except in accordance with Paragraph 13 of the Master Lease
         except that Subtenant may assign its rights under the Sublease to its
         subsidiaries or affiliates at its sole discretion without the consent
         of Landlord or Tenant.


CONSENT TO SUBLEASE -- 16th FLOOR                                              2



<PAGE>   61

6.       No Alterations.

         Landlord has no obligation to renovate or alter the Sublet Premises.
         Landlord has no, and Subtenant waives any, liability to Subtenant for
         any existing defects in construction of the Sublet Premises, patent or
         latent. Any alterations to the Sublet Premises may be performed only as
         specified in the Master Lease.

7.       Notices.

         All notices, requests, approvals, and other communications required or
         permitted to be delivered under this Consent must be in writing and are
         effective:

         a.       on the business day sent if sent by telecopier prior to 5:00
                  PM, Dallas, Texas time, and the sending telecopier generates a
                  written confirmation of sending;

         b.       the next business day after delivery on a business day to a
                  nationally-recognized-Overnight-courier service for prepaid
                  overnight delivery;

         c.       if orderly delivery of the mail is not then disrupted or
                  threatened, in which event some method of delivery other than
                  the mail must be used, 3 days after being deposited in the
                  United States mail, certified, return receipt requested,
                  postage prepaid; or

         d.       upon receipt if delivered personally or by any method other
                  than by telecopier (with written confirmation),
                  nationally-recognized-overnight-courier service, or mail;

         in each instance addressed to Landlord, Tenant, or Subtenant, as the
         case may be, at the respective addresses specified below, or to any
         other address any party may designate by 10 days prior notice to the
         other parties.

                  Landlord:          TIAA Realty, Inc.
                                     c/o Cousins Stone, L.P.
                                     5215 N. O'Connor Blvd.
                                     Suite 2602
                                     Irving, TX 75039
                                     Attn:  M. Scott Ozymy
                                     Fax:   972/432-3605

                  Tenant:            TIG Insurance Company
                                     5205 N. O'Connor Blvd.
                                     Suite W559
                                     Irving, TX 75039
                                     Attn: Tom Miller
                                     Fax: 972/831-5833



CONSENT TO SUBLEASE -- 16TH FLOOR                                              3



<PAGE>   62



                        Subtenant:Advance Paradigm, Inc.


         Subtenant is not entitled to receive any notices either Landlord or
         Tenant is required or permitted to give under the Master Lease.

8.       Headings.

         Paragraph headings or captions are used in this Consent for convenience
         only and do not limit or otherwise affect the meaning of any provision
         of this Consent.

9.       Attorneys' Fees.

         The prevailing party in any litigation concerning the interpretation or
         enforcement of this Consent may recover from the losing party(ies)
         reasonable attorneys' fees, court costs and expenses, whether at the
         trial or any appellate level.

10.      Governing Law.

         THE LAWS OF THE STATE OF TEXAS GOVERN THIS CONSENT.

11.      No Recordation.

         Neither Tenant nor Subtenant may record this Consent, the Master Lease,
         or the Sublease in the Real Property Records of Dallas County, Texas,
         or elsewhere.

12.      Severability.

         If any provision in this Consent is unenforceable in any respect, the
         remainder of this Consent is still enforceable.

13.      Rule of Construction.

         Each party and its counsel have reviewed and revised this Consent. Any
         rule of construction to the effect that any ambiguities are to be
         resolved against the drafting party may not be employed in the
         interpretation of this Consent or any amendments, schedules, or
         exhibits hereto.

14.      No Representations or Warranties.

         Neither Landlord nor Landlord's agents made, and Subtenant waives, any
         representations or warranties to Subtenant with respect to the Leased
         Premises, the Sublet Premises, the Building, or the Master Lease.



CONSENT TO SUBLEASE -- 16TH FLOOR                                              4



<PAGE>   63




15.      Entire Agreement.

         This Consent sets forth the entire agreement among the parties with
         respect to the Landlord's consent to the Sublease and no amendment or
         modification of this Consent is binding or valid unless expressed in
         writing executed by Landlord, Tenant, and Subtenant.

16.      Binding Effect.

         This Consent is binding upon Landlord, Tenant, and Subtenant and their
         respective heirs, personal representatives, successors, and permitted
         assigns.

         Executed effective as of the date and year first above written.

                             LANDLORD

                             TIAA Realty, Inc., a Delaware corporation
                             By:  Teachers Insurance and Annuity Association of
                             America, its authorized representative

                             By: /s/ LEONARD BALDUCCI
                                ------------------------------------------------
                             Name:   Leonard Balducci
                                  ----------------------------------------------
                             Title:  Associate Director
                                   ---------------------------------------------




                             TENANT


                             TIG INSURANCE COMPANY

                             By: /s/ L.P. MCCLIMON
                                ------------------------------------------------
                             Name:   L.P. McClimon
                                  ----------------------------------------------
                             Title:  Managing Director
                                   ---------------------------------------------


                             By:   /s/ THOMAS J. MILLER
                                   ---------------------------------------------
                             Name:     Thomas J. Miller
                                   ---------------------------------------------
                             Title:    Director -- Administration
                                   ---------------------------------------------



CONSENT TO SUBLEASE -- 16TH FLOOR                                              5



<PAGE>   64




                             SUBTENANT


                             ADVANCE PARADIGM, INC.

                             By: /s/ JON S. HALBERT
                                ------------------------------------------------
                             Name:   Jon S. Halbert
                                   ---------------------------------------------
                             Title:  EVP & COO
                                   ---------------------------------------------




CONSENT TO SUBLEASE -- 16TH FLOOR                                              6