<PAGE>

                                                                   Exhibit 10.32

                                   GROSS LEASE
                                (w/Base Amounts)

THIS LEASE (this "Lease") is made as of December ___, 2003, by and between

"Landlord"     Corporate Drive Corporation, as Trustee of Corporate Drive
               Nominee Realty Trust, a Massachusetts nominee trust

               and

"Tenant"       Lightbridge, Inc, a Delaware corporation.

                                TABLE OF CONTENTS

<TABLE>
<S>                                                                                              <C>
SECTION 1: DEFINITIONS..................................................................         1
   Access Laws..........................................................................         1
   Additional Rent......................................................................         1
   Base Amount Allocable to the Premises................................................         1
   Base Rent............................................................................         1
   Brokers..............................................................................         1
   Building.............................................................................         1
   Business Day.........................................................................         1
   Claims...............................................................................         1
   Commencement Date....................................................................         1
   Construction Period Commencement Date................................................         1
   ERISA................................................................................         1
   Estimated Operating Costs Allocable to the Premises..................................         1
   Events of Default....................................................................         1
   Fair Market Rent.....................................................................         1
   Governmental Agency..................................................................         2
   Governmental Requirements............................................................         2
   Hazardous Substance(s):..............................................................         2
   Land.................................................................................         2
   Landlord.............................................................................         2
   Landlord's Agents....................................................................         2
   Lease Security Deposit...............................................................         2
   Lease Term...........................................................................         2
   Lender...............................................................................         2
   Manager..............................................................................         2
   Manager's Address....................................................................         2
   Operating Costs......................................................................         2
   Operating Costs Allocable to the Premises............................................         2
   Park.................................................................................         2
   Parking Ratio........................................................................         2
   Permitted Use........................................................................         2
   Plans and Specifications.............................................................         2
   Prepaid Rent.........................................................................         2
   Premises.............................................................................         2
   Prime Rate...........................................................................         3
   Property Taxes.......................................................................         3
   Restrictions.........................................................................         3
   Telecommunication Facilities.........................................................         3
   Telecommunication Services...........................................................         3
   Tenant...............................................................................         3
   Tenant Alterations...................................................................         3
   Tenant Improvement Allowance.........................................................         3
</TABLE>

<PAGE>

<TABLE>
<S>                                                                                             <C>
   Tenant Improvements..................................................................         3
   Tenant's Agents......................................................................         3
   Tenant's  Pro Rata Share.............................................................         4
   Year.................................................................................         4
SECTION 2:  PREMISES AND TERM...........................................................         4
   2.1   Lease of Premises..............................................................         4
   2.2   Lease Term.....................................................................         5
   2.3   Plans and Specifications.......................................................         6
   2.4   Commencement Date..............................................................         7
   2.5   Tenant's Contribution to Tenant Improvement Costs..............................         7
   2.6   Intentionally Omitted..........................................................         9
   2.7   Use and Conduct of Business....................................................         9
   2.8   Compliance with Governmental Requirements and Rules and Regulations............        10
SECTION 3:  BASE RENT, ADDITIONAL RENT AND OTHER SUMS PAYABLE UNDER LEASE...............        10
   3.1   Payment of Rental..............................................................        10
   3.2   Base Rent......................................................................        10
   3.3   Lease Security Provisions......................................................        10
   3.4   Additional Rent................................................................        12
   3.5   Utilities......................................................................        16
   3.6   Holdover.......................................................................        17
   3.7   Late Charge....................................................................        17
   3.8   Default Rate...................................................................        17
SECTION 4:  MANAGEMENT AND LEASING PROVISIONS...........................................        17
   4.1   Maintenance and Repair by Landlord.............................................        17
   4.2   Maintenance and Repair by Tenant...............................................        19
   4.3   Common Areas/Security..........................................................        19
   4.4   Tenant Alterations.............................................................        20
   4.5   Tenant's Work Performance......................................................        20
   4.6   Surrender of Possession........................................................        20
   4.7   Removal of Property............................................................        21
   4.8   Access.........................................................................        21
   4.9   Damage or Destruction..........................................................        22
   4.10  Condemnation...................................................................        23
   4.11  Parking........................................................................        23
   4.12  Indemnification................................................................        23
   4.13  Tenant Insurance...............................................................        24
   4.14  Landlord's Insurance...........................................................        25
   4.15  Waiver of Subrogation..........................................................        25
   4.16  Assignment and Subletting by Tenant............................................        25
   4.17  Assignment by Landlord.........................................................        27
   4.18  Estoppel Certificates and Financial Statements.................................        27
   4.19  Modification for Lender........................................................        28
   4.20  Hazardous Substances...........................................................        28
   4.21  Access Laws....................................................................        28
   4.22  Quiet Enjoyment................................................................        29
   4.23  Signs..........................................................................        29
   4.24  Subordination..................................................................        30
   4.25  Workers Compensation Immunity..................................................        31
   4.26  Brokers........................................................................        31
   4.27  Limitation on Recourse.........................................................        31
   4.28  Mechanic's Liens and Tenant's Personal Property Taxes..........................        32
   4.29  Rooftop Equipment..............................................................        32
   4.30  Generator......................................................................        34
   4.31  No Offset; Independent Covenants; Waiver.......................................        35
SECTION 5:  DEFAULT AND REMEDIES........................................................        36
   5.1   Events of Default..............................................................        36
</TABLE>

                                       ii

<PAGE>

<TABLE>
<S>                                                                                             <C>
   5.2   Remedies.......................................................................        36
   5.3   Right to Perform...............................................................        38
   5.4   Landlord's Default.............................................................        38
SECTION 6:  MISCELLANEOUS  PROVISIONS...................................................        39
   6.1   Notices........................................................................        39
   6.2   Attorney's Fees and Expenses...................................................        39
   6.3   No Accord and Satisfaction.....................................................        39
   6.4   Successors; Joint and Several Liability........................................        39
   6.5   Choice of Law..................................................................        39
   6.6   No Waiver of Remedies..........................................................        39
   6.7   Offer to Lease.................................................................        40
   6.8   Force Majeure..................................................................        40
   6.9   Landlord's Consent.............................................................        40
   6.10  Severability; Captions.........................................................        40
   6.11  Interpretation.................................................................        40
   6.12  Incorporation of Prior Agreement; Amendments...................................        40
   6.13  Authority......................................................................        40
   6.14  Time of Essence................................................................        41
   6.15  Survival of Obligations........................................................        41
   6.16  Consent to Service.............................................................        41
   6.17  Landlord's Authorized Agents...................................................        41
   6.18  Waiver of Jury Trial...........................................................        41
   6.19  Building Deliveries............................................................        41
</TABLE>

                               LISTING OF EXHIBITS

<TABLE>
<S>               <C>
Exhibit A         Intentionally Omitted
Exhibit B         Drawing Showing Location and Configuration of the Premises
Exhibit C         Listing of Plans and Specifications for Tenant Improvements
Exhibit D         Intentionally Omitted
Exhibit E         Rules and Regulations
Exhibit F         Letter of Credit Criteria
Exhibit G         Exterior Signs
Exhibit H         Form of Requisition for Tenant Improvement Allowance
Exhibit I         Cleaning Specifications
Exhibit J         Tenant's Generator Area
Exhibit K         Prior Rights of First Offer and/or First Refusal
</TABLE>

                                      iii

<PAGE>

                             SECTION 1: DEFINITIONS

ACCESS   LAWS: The Americans With Disabilities Act of 1990 (including the
         Americans with Disabilities Act Accessibility Guidelines for Building
         and Facilities) and all other Governmental Requirements relating to the
         foregoing.

ADDITIONAL RENT:  Defined in paragraph captioned "Additional Rent".

BASE AMOUNT ALLOCABLE TO THE PREMISES: Defined in paragraph captioned
         "Additional Rent".

BASE RENT: The monthly amount of Base Rent and the portion of the Lease Term
         during which such monthly amount of Base Rent is payable shall be
         determined from the following table. For convenience and ease of
         reference, the annual rental rate for the computation of Base Rent and
         the annual Base Rent are also set forth in tabular form with the annual
         Base Rent equaling the monthly Base Rent installment multiplied by
         twelve. In the case of any conflict or inconsistency between the
         Monthly Base Rent installment and the other illustrative figures set
         forth in tabular form or in any computations utilizing such figures,
         the monthly Base Rent installment so specified shall be controlling and
         conclusive.

<TABLE>
<CAPTION>
        Applicable Portion of Lease Term
-----------------------------------------------
                                                                                                      Monthly Base
                                                             Rate Per/Rentable  Annual Base Rent    Rent Installment
Beginning                     Ending                         Sq. Ft./ Annum                          (Annual / 12)
--------------------------------------------------------------------------------------------------------------------
<S>                           <C>                            <C>                <C>                 <C>
Construction  Period          May 31, 2004                        $ 0.00          $        0.00        $      0.00
Commencement Date

June 1, 2004                  May 31, 2006                        $19.50          $1,569,496.50        $130,791.38

June 1, 2006                  May 31, 2007                        $20.50          $1,649,983.50        $137,498.63

June 1, 2007                  May 31, 2009                        $21.50          $1,730,470.50        $144,205.88

June 1, 2009                  November 30, 2011                   $22.85          $1,839,127.95        $153,260.66
</TABLE>

Notwithstanding the foregoing, Landlord shall abate all Base Rent applicable to
the Premises for the six (6) month period beginning on the Commencement Date
(i.e. June 1, 2004) and ending on December 1, 2004. Tenant acknowledges and
agrees that Tenant shall be liable for all Additional Rent payable during such
period.

BROKERS: Tenant was represented in this transaction by Meredith & Grew, Inc., a
         licensed real estate broker. Landlord was represented in this
         transaction by Trammell Crow Company, a licensed real estate broker.

BUILDING:The building located on the Land at 30 Corporate Drive, Burlington,
         Massachusetts, commonly known as 300 Burlington Centre and containing
         approximately 135,276 rentable square feet.

BUSINESS DAY: Calendar days, except for Saturdays and Sundays and holidays when
         banks are closed in Boston, Massachusetts.

CLAIMS: An individual and collective reference to any and all claims, demands,
         damages, injuries, losses, liens, liabilities, penalties, fines,
         lawsuits, actions, other proceedings and expenses (including reasonable
         attorneys' fees and expenses incurred in connection with the proceeding
         whether at trial or on appeal).

COMMENCEMENT DATE: June 1, 2004.

CONSTRUCTION PERIOD COMMENCEMENT DATE: The date that this Lease has been fully
         executed and delivered by both parties.

ERISA: The Employee Retirement Income Security Act of 1974, as now or hereafter
         amended, and the regulations promulgated under it.

ESTIMATED OPERATING COSTS ALLOCABLE TO THE PREMISES: Defined in paragraph
         captioned "Additional Rent".

EVENTS OF DEFAULT: One or more of those events or states of facts defined in the
         paragraph captioned "Events of Default".

FAIR MARKET RENT: The prevailing base rent and additional rent (including
         provisions for escalations, subsequent increases, market incentives
         such as tenant improvements and free rent periods, and other
         adjustments) for new leases or lease renewals (as applicable) of a
         comparable term then

                                       1

<PAGE>

         currently being negotiated or executed for comparable space located in
         similar first class office buildings in Burlington, Massachusetts (the
         "Comparable Properties"), considering the relative age, condition and
         location of the Building and the Comparable Properties, the relative
         condition of the Building's and Comparable Properties' systems; the
         relative condition of the Premises and such comparable space; the
         absence of rent concessions and work to be performed by Landlord for
         Tenant's benefit; and the absence of any contribution by Landlord for
         any work to be performed by Tenant or on Tenant's behalf..

GOVERNMENTAL AGENCY: The United States of America, the state in which the Land
         is located, any county, city, district, municipality or other
         governmental subdivision, court or agency or quasi-governmental agency
         having jurisdiction over the Land and any board, agency or authority
         associated with any such governmental entity, including the fire
         department having jurisdiction over the Land.

GOVERNMENTAL REQUIREMENTS: Any and all statutes, ordinances, codes, laws, rules,
         regulations, orders and directives of any Governmental Agency as now or
         later amended.

HAZARDOUS SUBSTANCE(S): Asbestos, PCBs, petroleum or petroleum-based chemicals
         or substances, urea formaldehyde or any chemical, material, element,
         compound, solution, mixture, sub-stance or other matter of any kind
         whatsoever which is now or later defined, classified, listed,
         designated or regulated as hazardous, toxic or radioactive by any
         Governmental Agency.

LAND: The land upon which the Building is located in Burlington, Middlesex
         County, Commonwealth of Massachusetts.

LANDLORD: The trust named on the first page of this Lease, or its successors and
         assigns as provided in paragraph captioned "Assignment by Landlord".

LANDLORD'S AGENTS: The trustee of and consultants and advisors to the Landlord
         and employees of the foregoing.

LEASE SECURITY DEPOSIT: The letter of credit delivered by Tenant to Landlord as
         described in the paragraph entitled "Security Provisions."

LEASE TERM: Commencing on the Construction Period Commencement Date and ending
         on November 30, 2011.

LENDER: Defined in paragraph entitled "Landlord's Default".

MANAGER: Trammell Crow Services, Inc., or its replacement as specified by
         written notice from Landlord to Tenant.

MANAGER'S ADDRESS: 25 Corporate Drive, Burlington, Massachusetts 01803, which
         address may be changed by written notice from Landlord to Tenant.

OPERATING COSTS: Defined in paragraph captioned "Additional Rent".

OPERATING COSTS ALLOCABLE TO THE PREMISES: Defined in paragraph captioned
         "Additional Rent".

PARK: The office park in which the Building is located, known as Burlington
         Centre Office Park.

PARKING RATIO: 3.1 stalls per 1,000 rentable square feet of the Premises.

PERMITTED USE: Office uses for general business, sales, and technical
         assistance; the operation of a data center with computers and related
         equipment; an emergency call center and training facilities, so long as
         any such use is consistent with Governmental Requirements.

PLANS AND SPECIFICATIONS: (a) Those certain plans and specifications for the
         Tenant Improvements, if any, as listed in Exhibit C and any
         modifications to them approved in writing by Landlord and Tenant; or
         (b) if Exhibit C does not include a listing of such plans and
         specifications, then such plans and specifications shall be prepared by
         Tenant (the "Preparing Party") and delivered to Landlord (the
         "Receiving Party") and approved by Landlord and Tenant as set forth in
         the paragraph entitled "Plans and Specifications".

PREPAID RENT: One Hundred Thirty Thousand and 00/100 Dollars ($130,000.00) to be
         applied toward Base Rent for the first full calendar month of the Lease
         Term or to the first month in which full Base Rent is due.

PREMISES:The portion of the Building consisting of approximately ten thousand
         six hundred twenty-one (10,621) rentable square feet on the first floor
         of the Building, the entire second floor of the Building containing
         approximately thirty-four thousand nine hundred thirty-three (34,933)
         rentable square feet, and the entire third floor of the Building
         containing approximately thirty-four thousand nine hundred thirty-three
         (34,933) rentable square feet, each of the foregoing as depicted on the
         plans attached as Exhibit B and agreed by Landlord and Tenant for all
         purposes under this Lease to consist of an aggregate of approximately
         eighty- thousand four hundred eighty-seven (80,487)

                                       2

<PAGE>

         rentable square feet. The number of rentable square feet recited herein
         shall be final, conclusive and controlling.

PRIME RATE: Defined in paragraph captioned "Default Rate".

PROPERTY TAXES: (a) Any form of ad valorem real or personal property tax or
         assessment imposed by any Governmental Agency on the Land, Building,
         related improvements located on the Land or any personal property owned
         by Landlord associated with such Land, Building or improvements; (b)
         any other form of tax or assessment, license fee, license tax, tax or
         excise on rent or any other levy, charge, expense or imposition made or
         required by any Governmental Agency on any interest of Landlord in such
         Land, Building, related improvements or personal property; (c) any fee
         for services charged by any Governmental Agency for any services such
         as fire protection, street, sidewalk and road maintenance, refuse
         collection, school systems or other services provided or formerly
         provided to property owners and residents within the general area of
         the Land; (d) any governmental impositions allocable to or measured by
         the area of any or all of such Land, Building, related improvements or
         personal property or the amount of any base rent, additional rent or
         other sums payable under any lease for any or all of such Land,
         Building, related improvements or personal property; (e) any gross
         receipts or other excise tax allocable to, measured by or a function of
         any one or more of the matters referred to in clause (d); (f) any
         impositions by any Governmental Agency on any transaction evidenced by
         a lease of any or all of such Land, Building, related improvements or
         personal property; (g) any increase in any of the foregoing based upon
         construction of improvements or change of ownership of any or all of
         such Land, Building, related improvements or personal property, (h) tax
         consultant fees and expenses, and (i) costs of appeals of any Property
         Taxes, provided that Landlord in good faith believes that there is a
         reasonable likelihood that a contest by Landlord will be successful in
         obtaining an abatement or reduction that will exceed the cost of any
         such contest. Notwithstanding the foregoing, Property Taxes shall not
         include taxes on Landlord's net income, franchise tax, capital levy
         tax, excise tax, transfer tax, or estate, gift, succession or
         inheritance taxes. Tenant shall not be required to share in any
         penalties, interest, late payments or the like resulting from
         Landlord's late payment of Property Taxes, provided Tenant has paid its
         share of the Property Taxes and all other amounts when and as required
         hereunder. In the event any special assessments are assessed and
         payable, Tenant's share thereof shall be calculated as if such
         assessments were being paid by Landlord over the longest period of time
         permitted by applicable law (including any interest charge associated
         therewith). If Property Taxes on the Building are increased as a result
         of alterations made by another tenant or occupant on its own premises,
         and if such alterations are separately listed and assessed on the tax
         bill and if such tenant's or occupant's lease or agreements with
         Landlord require such tenant or occupant to pay one hundred percent
         (100%) of such increase, then Tenant shall not be required to pay any
         share of such separately listed Property Tax amount.

RESTRICTIONS: Any covenants, conditions and restrictions applicable to the Land
         which are recorded with the Middlesex County (Southern District)
         Registry of Deeds.

TELECOMMUNICATION FACILITIES: Equipment, facilities, apparatus and other
         materials utilized for the purpose of electronic telecommunication,
         including cable, switches, wires, conduit and sleeves.

TELECOMMUNICATION SERVICES: Services associated with electronic
         telecommunications, whether in a wired or wireless mode. Basic voice
         telephone services are included within this definition.

TENANT: The person or entity(ies) named on the first page of this Lease.

TENANT ALTERATIONS: Defined in paragraph captioned "Tenant Alterations".

TENANT IMPROVEMENT ALLOWANCE: The maximum amount, if any, to be contributed by
         Landlord to reimburse Tenant for Tenant Improvement Costs and the
         Construction Monitoring Fee (each as defined in paragraph 2.5.1
         hereof), which maximum shall not exceed Three Million Two Hundred
         Ninety-Nine Thousand Nine Hundred Sixty-Seven and 00/100 Dollars
         ($3,299,967.00) or Forty-One and 00/100 Dollars ($41.00) per rentable
         square foot of the Premises.

TENANT IMPROVEMENTS: Those alterations or improvements to the Premises as appear
         and are depicted in the Plans and Specifications.

TENANT'S AGENTS: Any and all officers, partners, contractors, subcontractors,
         consultants, licensees, agents, concessionaires, subtenants, servants,
         employees, customers, guests, invitees or visitors of Tenant.

                                       3

<PAGE>

TENANT'S PRO RATA SHARE : is 80,487/135,276 = fifty-nine and fifty
         one-hundredths percent (59.50%), which shall be final, conclusive and
         controlling during the Lease Term for all purposes, except as the same
         may be adjusted to reflect any expansion of the Premises or the
         recapture of any portion thereof.

YEAR: A calendar year commencing January 1 and ending December 31 or that
         portion of the calendar year within the Lease Term.

                          SECTION 2: PREMISES AND TERM

2.1      LEASE OF PREMISES.

         2.1.1    INITIAL PREMISES. Landlord leases the Premises to Tenant, and
Tenant leases the Premises from Landlord, upon the terms and conditions set
forth in this Lease. In addition to the Premises, Tenant shall have the
nonexclusive right, in common with Landlord and all others to whom Landlord has
granted or may hereafter grant rights, to use the common lobbies, corridors,
stairways, elevators and loading platforms of the Building and the common
walkways and driveways necessary for access to the Building, and if the Premises
include less than an entire floor, the common toilets, corridors and elevator
lobby for such floor. Tenant's use of such common areas shall be subject to such
reasonable regulations as Landlord may from time to time impose and the rights
of Landlord set forth herein.

         2.1.2    EXPANSION SPACE - RIGHT OF FIRST OPPORTUNITY. During the
initial Lease Term (but not during any extension of this Lease pursuant to
paragraph 2.2.2 hereof), provided the Tenant is not in default of any of the
terms, covenants and conditions thereof, beyond any applicable notice and cure
periods, and further provided that Lightbridge, Inc. is itself occupying at
least sixty (60%) percent of the initial Premises demised to Tenant as of the
date of this Lease (the "Initial Premises"), in the event that any other space
in the Building (in each case referred to herein as "Expansion Space") shall
become available for lease in the Building after the date hereof as a result of
the expiration or termination of any lease now existing or hereafter entered
into, Landlord shall first offer such Expansion Space to Tenant on an "AS IS"
basis for the balance of the Lease Term, subject to any prior rights of first
offer and/or first refusal held by third parties as of the date of this Lease as
set forth on Exhibit K attached hereto and subject to the renewal rights of any
then existing tenants. Notwithstanding the foregoing, if less than two (2) years
were to remain on the initial Lease Term as of the effective commencement date
for such Expansion Space, Tenant may not exercise such right of first offer
unless Tenant exercises the Extension Option. The Base Rent and Additional Rent
payable for the affected Expansion Space shall be the then Fair Market Rent for
new leases of such space as determined in the same manner as Fair Market Rent is
determined for the Extension Option as provided in paragraph 2.2.3 hereof.
Notwithstanding the foregoing or anything to the contrary contained in paragraph
2.1.3 hereof, (a) if the effective commencement date for such Expansion Space
occurs on or before June 1, 2006, in no event shall the Base Rent plus
escalations for any Expansion Space be less than the annual Base Rent per
rentable square foot plus escalations payable for the Premises from time to
time, and (b) Landlord shall have no obligation to prepare, refurbish or
construct the Expansion Space or any part thereof or to otherwise provide any
amount of improvement allowance in respect of the Expansion Space. Tenant shall
have ten (10) Business Days from notification of Landlord (the "ROFO Notice")
within which to accept Landlord's offer in writing to lease all or any portion
of such Expansion Space, provided that if Tenant elects to lease less than all
of such Expansion Space, the remainder of such Expansion Space to be retained by
Landlord shall consist of a single leasable space of not less than five thousand
(5,000) rentable square feet. Although the Fair Market Rent shall be determined
in accordance with paragraph 2.2.3 hereof, the ROFO Notice shall state
Landlord's proposed Fair Market Rent for such Expansion Space. If Tenant has not
accepted Landlord's offer in writing within said ten (10) Business Day time
period and/or has not executed an amendment to this Lease in form and substance
satisfactory to Landlord in its reasonable discretion within five (5) Business
Days after Landlord's delivery of same to the Tenant (in each case time being of
the essence), this right of first opportunity shall expire as to such Expansion
Space, and the Landlord shall be free to lease all or any portion of such
Expansion Space to any third party at any time thereafter on the same terms and
conditions as offered to Tenant or on such other terms and conditions as
Landlord shall determine provided such terms and conditions are not more
favorable than those offered to Tenant. If Landlord thereafter decides to offer
such Expansion Space to a third party on terms more favorable than those
previously offered to Tenant as provided above, then, subject to the terms and
conditions provided above, Landlord shall again first offer such Expansion Space
to Tenant by ROFO Notice, except that Tenant

                                       4

<PAGE>

shall only have three (3) Business Days from receipt of such ROFO Notice within
which to accept Landlord's offer in writing. If Tenant has not accepted
Landlord's offer in writing within said three (3) Business Day time period
and/or has not executed an amendment to this Lease in form and substance
satisfactory to Landlord in its reasonable discretion within five (5) Business
Days after Landlord's delivery of same to the Tenant (in each case time being of
the essence), this right of first opportunity shall expire as to such Expansion
Space, and the Landlord again shall be free to lease all or any portion of such
Expansion Space to any third party at any time thereafter on the same terms and
conditions as offered to Tenant or on such other terms and conditions as
Landlord shall determine provided such terms and conditions are not more
favorable than those offered to Tenant. Any exercise of a right of first offer
by Tenant as provided herein shall be irrevocable, whether or not Fair Market
Rent has been determined as of such date. If the Fair Market Rent has not been
determined as of the effective date of any such expansion, Tenant initially
shall pay Base Rent plus escalations for the Expansion Space at the same rate
payable for the Premises, with a retroactive adjustment to be made within ten
(10) Business Days after the determination of Fair Market Rent. In the event
that Tenant does not elect to exercise its right of first offer with respect to
any Expansion Space and such Expansion Space shall become available again during
the Lease Term as a result of the termination or expiration of any lease
subsequently entered into by Landlord with respect to such space, Landlord shall
again offer such Expansion Space to Tenant pursuant to the procedures set forth
above. Since approximately twelve thousand eight hundred eighty-six (12,886)
rentable square feet of space on the first floor of the Building which are
described as "Vacant 12,886 SF" on the plans attached hereto as Exhibit B are
available as of the Commencement Date, Tenant shall be deemed not to have
exercised its right of first offer with respect to such space and Landlord shall
have no obligation to offer such space to Tenant again until after the
expiration or termination of any lease of such space hereafter entered into by
Landlord.

2.2      LEASE TERM.

         2.2.1    INITIAL LEASE TERM. The Lease Term shall be for the period
stated in the definition of that term, unless earlier
terminated as provided in this Lease.

         2.2.2    OPTION TO EXTEND. While the Lease is in full force and effect,
provided the Tenant is not in default of any of the terms, covenants and
conditions thereof, beyond any applicable notice and cure periods, and further
provided that Lightbridge, Inc. is itself occupying at least sixty percent (60%)
of the Initial Premises, in each case both as of the time of option exercise and
as of the commencement of the herein additional term, Tenant shall have the
right or option (the "Extension Option") to extend the original term of this
Lease for one (1) period of five (5) years. Such extension of the original term
shall be on the same terms, covenants and conditions as provided for in the
original term except (a) Tenant shall have no further option to extend the term,
(b) the base year for Property Taxes and Operating Expenses (net of Property
Taxes) shall be updated to then current calendar year and fiscal tax year as of
the date of exercise of the Extension Option, (c) the Base Rent shall be the
Fair Market Rent as determined in accordance with paragraph 2.2.3 hereof (taking
into account such new base years), and (d) Landlord shall have no obligation to
prepare, refurbish or construct the Premises or any part thereof prior to the
commencement of the herein additional term or otherwise provide any amount of
improvement allowance in respect of the Premises. Any exercise of such Extension
Option by Tenant as provided herein shall be irrevocable, whether or not Fair
Market Rent has been determined as of such date. If the Fair Market Rent has not
been determined as of the commencement date of such additional term, Tenant
initially shall pay Base Rent plus escalations for the extended term at the same
rates payable for the Premises as of the date immediately preceding the
commencement of such additional term, with a retroactive adjustment to be made
within ten (10) Business Days after the determination of Fair Market Rent.
Notice (the "Option Notice") of Tenant's intention to exercise the Extension
Option must be given to Landlord, in writing, at least twelve (12) months prior
to the expiration of the initial term of the Lease.

         2.2.3    DETERMINATION OF FAIR MARKET RENT FOR EXTENSION OPTION. If
Tenant exercises the Extension Option as provided above, Landlord and Tenant
shall have a period of twenty (20) days after Landlord's receipt of the Option
Notice to agree upon the Fair Market Rent for the Premises. If Landlord and
Tenant fail to reach agreement on the Fair Market Rent for the Premises, then
the Fair Market Rent for the Premises shall be determined by three (3) licensed
commercial real estate brokers, one of whom shall be named by Landlord, one of
whom shall be named by Tenant, and the third of whom shall be selected by the
brokers chosen by Landlord and by Tenant. All such brokers shall be independent
and none of the brokers nor their firms shall have been employed by Landlord
(with respect to the Building), Tenant (with respect to the Building) or their
affiliates for the immediately preceding five (5) years. A broker shall not be

                                       5

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disqualified if he/she or their firm have been employed by Landlord or Tenant
within the preceding five (5) years with respect to any property other than the
Building. Furthermore, each such broker shall be a commercial real estate broker
licensed in Massachusetts, specializing in commercial office leasing in the so
called "Route 128 corridor" in Massachusetts, with not less than ten (10) years
experience in appraising comparable commercial properties in the Route 128
corridor and recognized as reputable within the local real estate industry (each
such broker being defined herein for purposes of this paragraph as a "Qualified
Broker"). The parties each agree to select their Qualified Broker within ten
(10) days after the expiration of the aforesaid twenty (20) day period. The
third Qualified Broker shall be selected within ten (10) days after the first
two (2) Qualified Brokers have been selected. If a party fails to timely select
a Qualified Broker, the determination of the Fair Market Rent for the Premises
shall be made by the Qualified Broker selected by the other party. Within
fifteen (15) days after the third Qualified Broker has been selected, all of the
Qualified Brokers shall meet to attempt to agree upon the Fair Market Rent for
the Premises. If the Qualified Brokers are unable to reach agreement, each
Qualified Broker shall, within fifteen (15) days after the expiration of the
preceding fifteen (15) day period, submit to Landlord and Tenant in writing the
Fair Market Rent for the Premises he or she deems appropriate (each such
Qualified Broker's determination of Fair Market Rent for purposes of this
paragraph being referred to herein as an "Appraisal"). The Fair Market Rent for
the Premises shall be the respective amounts which are the mean between the
closest two (2) Appraisals for each such space determined by the Qualified
Brokers, provided that the higher of such Appraisals does not exceed the lower
of such Appraisals by more than ten percent (10%). If such Appraisal exceeds the
other by more than ten percent (10%), the two (2) remaining brokers (as used in
this paragraph, the "Remaining Qualified Brokers") shall select another
Qualified Broker (as used in this paragraph, the "Fourth Qualified Broker").
Within fifteen (15) days after the Fourth Qualified Broker has been selected,
the Remaining Qualified Brokers and the Fourth Qualified Broker shall meet to
attempt to agree upon the Fair Market Rent for the Premises. If the Remaining
Qualified Brokers and the Fourth Qualified Broker are unable to reach agreement,
each such Qualified Broker shall, within fifteen (15) days after the expiration
of the preceding fifteen (15) day period, submit to Landlord and Tenant in
writing the Fair Market Rent for the Premises he or she deems appropriate. The
Fair Market Rent for the Premises shall be the respective amounts which are the
mean between the three (3) Appraisals for each such space determined by the
Remaining Qualified Brokers and the Fourth Qualified Broker. The Fair Market
Rent for the Premises determined in accordance with this paragraph 2.2.3 shall
be final and binding on Landlord and Tenant. Each of the parties to this Lease
shall pay the costs of the services of the Qualified Broker selected by that
party, and the cost of the services of the third Qualified Broker and the Fourth
Qualified Broker shall be divided equally between Landlord and Tenant. After the
Fair Market Rent for the Premises has been determined as herein provided, the
parties shall execute an amendment to this Lease setting forth the terms
resulting from the exercise of the Extension Option.

2.3      PLANS AND SPECIFICATIONS.

         2.3.1    If there are no Plans and Specifications attached as Exhibit
C, then Tenant shall retain a licensed architect of its choice, subject to
Landlord's prior written approval (which approval shall not be unreasonably
withheld, conditioned or delayed), to prepare the Plans and Specifications for
the Tenant Improvements. The plans and specifications shall be subject to
Landlord's approval, which approval shall not be unreasonably withheld,
conditioned or delayed, provided that such Plans and Specifications comply with
the requirements of this paragraph 2.3.

         2.3.2    Within ninety (90) days following the date of execution of the
Lease by Tenant, Tenant shall cause its architect to furnish to Landlord for
Landlord's approval space plans sufficient to convey the architectural design of
the Premises, including, without limitation, the location of doors, partitions,
electrical and telephone outlets, plumbing fixtures, heavy floor loads and other
special requirements (collectively, the "Space Plan"). If required by Landlord,
Tenant's architect shall consult with Landlord's engineer in preparing the Space
Plan, and incorporate such engineer's reasonable requirements into the Space
Plan. The reasonable fees of such engineer shall be a Tenant Improvement Cost
(as hereafter defined). If Landlord shall disapprove of any portion of the Space
Plan, Landlord shall advise Tenant of the reasons therefor within seven (7)
Business Days of receipt of the Space Plan from Tenant and shall notify Tenant
within such seven (7) Business Day period of the revisions to the Space Plan
that are reasonably required by Landlord together with an explanation why such
revisions are required for the purpose of obtaining approval. Tenant shall
within seven (7) days submit to Landlord, for Landlord's approval, a redesign of
the Space Plan, incorporating the revisions reasonable required by Landlord.

                                       6

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         2.3.3    Tenant shall cause its architect to prepare from Tenant's
approved Space Plan, complete Plans and Specifications within thirty (30) days
after Landlord approves the Space Plan. The Plans and Specifications shall (a)
be compatible with the Building shell and with the design, construction and
equipment of the Building; (b) comply with all Governmental Requirements; (c)
comply with all applicable insurance regulations; (d) be consistent with the
approved Space Plan, and (e) in a form sufficient for the permitting and
construction of the Tenant Improvements shown thereon. If Landlord shall
disapprove of any portion of the Plans and Specifications, Landlord shall advise
Tenant of the reasons therefor within seven (7) Business Days of receipt thereof
and shall notify Tenant within such seven (7) Business Day period of the
revisions to the Plans and Specifications that are reasonably required by
Landlord for the purpose of obtaining approval. Tenant shall within seven (7)
days submit to Landlord, for Landlord's approval, a redesign of the Plans and
Specifications, incorporating the revisions reasonably required by Landlord.

         2.3.4    In the event that Landlord approves any changes in the Plans
and Specifications, Tenant shall cause its architect to provide documentation
for such changes at the time each such change is authorized for construction
pursuant to Paragraph 2.5.1. At the conclusion of construction of the Tenant
Improvements, Tenant shall cause its architect to update Tenant's plans and
specifications as necessary to reflect all changes to the Plans and
Specifications during the course of construction of the Tenant Improvements and
to issue a set of sepias to the contractor for its review and mark up. Tenant
shall cause its architect to review and certify the contractor's marked up plans
and provide to Landlord a "record set" of as-built sepias within thirty (30)
days following completion of the Tenant Improvements.

2.4      COMMENCEMENT DATE. Following the execution and delivery of this Lease
by all parties hereto, Landlord shall deliver possession of the Premises to the
Tenant. Prior to such delivery, Landlord shall fill and level all cracks in the
second and third floors which are over one-half inch in depth. Tenant
acknowledges that, except as provided in the immediately preceding sentence, the
Premises shall be delivered AS IS and that no representations as to the
condition of the Premises have been made by Landlord. The taking of possession
by Tenant shall establish that the Premises are in good and satisfactory
condition when possession was so taken and the Commencement Date shall occur as
provided in the definition of that term. In no event shall Tenant's refusal or
failure to take possession of the Premises delay or postpone the occurrence of
the Construction Period Commencement Date or the Commencement Date.

2.5      TENANT'S CONTRIBUTION TO TENANT IMPROVEMENT COSTS.

         2.5.1    Upon receipt of possession of the Premises, the Tenant shall
prepare the Premises for Tenant's occupancy and complete the Tenant Improvements
in accordance with the Plans and Specifications and at the Tenant's sole cost
and expense (all such costs and expenses, including all hard and soft costs such
as and without limitation, all labor and materials, architectural, engineering,
permitting, and space planning fees are hereinafter collectively referred to as
the "Tenant Improvement Costs"). Except as expressly permitted under the
immediately following sentence, Tenant shall make no changes to the Plans and
Specifications or the work reflected in the Plans and Specifications without the
prior written consent of the Landlord, which consent shall not be unreasonably
withheld, conditioned or delayed. Tenant may make changes to the Plans and
Specifications without the Landlord's consent provided that (a) such changes
relate solely to the interior of the Premises, are non-structural, and do not
affect any of the Building's mechanical, HVAC, electrical, plumbing or other
systems, and (b) the cost of the Tenant Improvements shall not increase or
decrease by more than Fifty Thousand Dollars ($50,000.00) as a result of any
individual change or by more than One Hundred Thousand Dollars ($100,000.00) in
the aggregate as a result of all such changes (and for purposes of measuring
such aggregate changes, increases and decreases shall both be deemed positive
numbers and shall not offset each other). Tenant's completion of the Tenant
Improvements shall be performed by Tenant's contractors, who shall work under
the direction of Tenant or Tenant's qualified representative. Landlord shall
have the right to have its representative at the Premises at all times during
the construction of the Tenant Improvements to review and monitor the
performance of same, and Tenant shall pay Landlord a construction monitoring fee
equal to three percent (3%) of the Tenant Improvement Costs (the "Construction
Monitoring Fee"). The Tenant Improvements shall be performed by contractors
selected by Tenant and approved by Landlord, which approval shall not be
unreasonably withheld, conditioned or delayed. Such contractors shall be
employed by Tenant under one or more construction contracts, in form and content
approved in advance in writing by Landlord (which approval shall be subject to
Landlord's reasonable discretion and may include a requirement that the prime
contractor and the respective

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<PAGE>

subcontractors of any tier: (a) be parties to, and bound by, a collective
bargaining agreement with a labor organization affiliated with the Building and
Construction Trades Council of the AFL-CIO and (b) employ only members of such
organization to perform work within their respective jurisdictions). Such
contractors also shall comply with all requirements in Paragraph 4.5 of this
Lease. In all events, Tenant shall furnish Landlord with a complete set of
as-built plans upon completion of the Tenant Improvements.

         2.5.2    All Tenant Improvements, regardless of which party constructed
or paid for them, shall become the property of Landlord and shall remain upon
and be surrendered with the Premises upon the expiration or earlier termination
of this Lease; provided that, at Landlord's election and upon notice to Tenant,
Tenant shall be required to remove all or any portion of the Tenant Improvements
(including Telecommunication Facilities) upon the expiration or earlier
termination of this Lease. Notwithstanding the foregoing, if Tenant's submission
of its Plans and Specifications to the Landlord for approval is accompanied by a
written request that Landlord identify any Tenant Improvements that Landlord may
require Tenant to remove upon the expiration or earlier termination of the
Lease, Landlord shall identify such Tenant Improvements (if any) by notice to
Tenant given at the time of Landlord's approval of the Plans and Specifications.

         2.5.3    Tenant shall be solely responsible for the design and
construction of the Tenant Improvements. Notwithstanding Landlord's review and
approval of the Plans and Specifications, Landlord shall have no liability to
Tenant or to any other person for errors or omissions in the Plans and
Specifications or in the construction of the Tenant Improvements (Landlord's
review and approval of the Plans and Specifications being for Landlord's own
purposes). Tenant shall rely solely on the advice and experience of Tenant's
architect in assuring the accuracy and sufficiency of the Plans and
Specifications. Tenant shall indemnify, defend, protect and hold Landlord's
Agents harmless from all Claims which arise in any way, directly or indirectly
from or in connection with the design of the Tenant Improvements, including
without limitation, claims arising from the work of Tenant's architect,
engineer, employees or agents.

         2.5.4    Landlord shall grant an allowance to Tenant in an amount up to
the Tenant Improvement Allowance (as defined in Section 1 hereof) to be used
solely to pay Tenant's contractors directly or to reimburse the Tenant for the
Tenant Improvement Costs and to pay the Construction Monitoring Fee. Subject to
the terms and conditions hereof, the Tenant Improvement Allowance shall be
available for disbursement for Tenant Improvement Costs in up to a maximum of
five (5) draws (each a "Tenant Allowance Advance") in the following manner. At
least twelve (12) Business Days before the date upon which the Tenant desires a
Tenant Allowance Advance, the Tenant shall submit an itemized requisition (a
"Requisition") on the form attached hereto as Exhibit H , stating the amount of
the advance, the items(s) to be paid from the proceeds thereof, and the date
upon which the advance is desired. Landlord's obligation to make any Tenant
Allowance Advance, other than the Final Tenant Allowance Advance (as defined
below), shall be subject to Tenant's satisfaction of all of the following
conditions other than item number (5), and Landlord's obligation to make the
Final Tenant Allowance Advance shall be subject to Tenant's satisfaction of each
and all of the following conditions numbered (1) through (5): (1) Tenant shall
have submitted to Landlord a certification signed by Tenant's architect
certifying that all work on the Tenant Improvements which has been completed
through the date of such certification (which shall be no earlier than the date
of the subject Requisition) has been completed in accordance with Plans and
Specifications approved by the Landlord and attaching thereto executed waivers
or releases of liens from each of Tenant's contractors, subcontractors and
suppliers for all work performed and materials delivered through the date of
such Requisition, which waivers and releases shall be in such form as Landlord
may reasonably require, (2) Tenant shall have submitted to Landlord a
certification of Tenant's general contractor identifying each contractor,
subcontractor and supplier who performed labor and/or supplied materials for the
Tenant Improvements through the date of such Requisition, (3) Tenant shall have
furnished Landlord with copies of third party invoices and, in the case of
Tenant's written request for reimbursement to it of paid construction costs,
evidence of payment of same, for all work performed and materials delivered with
respect to the Tenant Improvements through the date of such Requisition, (4) at
the time of such Tenant Allowance Advance there shall exist no event which is,
or solely with the passage of time and/or giving of notice would be, an Event of
Default, and (5) with respect to the Final Tenant Allowance Advance, Tenant
shall have submitted to Landlord an issued and effective certificate of
occupancy for the Premises for the Permitted Use, and a certification signed by
Tenant's architect certifying that the Tenant Improvements have been completed
in accordance with Plans and Specifications approved by the Landlord and
attaching thereto executed final waivers or releases of liens from each of
Tenant's contractors, subcontractors and suppliers in connection with the Tenant
Improvements in such form as Landlord may reasonably require, plus a

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<PAGE>

certificate of Tenant's general contractor identifying each contractor,
subcontractor and supplier who performed labor and/or supplied materials for the
Tenant Improvements. The foregoing items (1) through (5) above are herein
collectively referred to as the "Tenant Allowance Conditions". Subject to
satisfaction of all of the Tenant Allowance Conditions applicable to a
particular Tenant Allowance Advance, Landlord shall pay to Tenant or directly to
Tenant's contractors, within twelve (12) Business Days after receipt by Landlord
of a written request from Tenant for a Tenant Allowance Advance in accordance
with the foregoing and specifying the recipient of payment, the lesser of (a)
the full amount of the remaining undisbursed Tenant Improvement Allowance, if
the aggregate sum of the invoices from contractors (or paid invoices in the case
of a request for reimbursement to Tenant) submitted pursuant to (3) above equals
or exceeds the full amount of the Tenant Improvement Allowance (less the
Construction Monitoring Fee), or (b) the aggregate sum of the invoices from
contractors (or paid invoices in the case of a request for reimbursement to
Tenant) submitted pursuant to (3) above, if said aggregate sum is less than the
full amount of the Tenant Improvement Allowance (and the Construction Monitoring
Fee). Except as provided in the last sentence of this paragraph, Tenant shall
not be entitled to any credit, trade off or cash payment for any unused portion
of the Tenant Improvement Allowance, and the Landlord shall have no obligation
to Tenant with respect to any such unused portion of the Tenant Improvement
Allowance. Upon completion of the Tenant Improvements and application of the
Tenant Improvement Allowance against the Tenant Improvement Costs and the
Construction Monitoring Fee, if the aggregate cost of the Tenant Improvements
and the Construction Monitoring Fee is less than the Tenant Improvement
Allowance, Tenant may elect to apply any unexpended balance of the Tenant
Improvement Allowance up to a maximum aggregate amount of Four Hundred Two
Thousand Four Hundred Thirty-Five and 00/100 Dollars ($402,435.00) against (x)
the monthly installments of Base Rent next becoming due hereunder until such
amount has been fully applied and/or (y) Tenant's remaining rent obligations
under its existing Lease of premises located at 67 South Bedford Street,
Burlington, Massachusetts.

2.6      INTENTIONALLY OMITTED.

2.7      USE AND CONDUCT OF BUSINESS.

         2.7.1    The Premises are to be used only for the Permitted Uses, and
for no other business or purpose without the prior consent of Landlord. Landlord
makes no representation or warranty as to the suitability of the Premises for
Tenant's intended use. Tenant shall, at its own cost and expense, obtain and
maintain any and all licenses, permits, and approvals necessary or appropriate
for its use, occupation and operation of the Premises for the Permitted Uses.
Tenant's inability to obtain or maintain any such license, permit or approval
necessary or appropriate for its use, occupation or operation of the Premises
shall not relieve it of its obligations under this Lease, including the
obligation to pay Base Rent and Additional Rent.

         2.7.2    No act shall be done in or about the Premises that is unlawful
or that will increase the existing rate of insurance on any or all of the Land
or Building, unless Tenant agrees to pay the entire cost of such increase. In
any event, any such act must comply with all terms and conditions of this Lease,
including without limitation, the Permitted Use. Tenant shall not commit or
allow to be committed or exist: (a) any waste upon the Premises, (b) any public
or private nuisance, or (c) any act or condition which disturbs the quiet
enjoyment of any other tenant in the Building, violates any of Landlord's
contracts affecting any or all of the Land or Building (provided Tenant has
knowledge of such contracts), creates or contributes to any work stoppage,
strike, picketing, labor disruption or dispute, interferes in any material way
with the business of Landlord or any other tenant in the Building or with the
rights or privileges of any contractors, subcontractors, licensees, agents,
concessionaires, subtenants, servants, employees, customers, guests, invitees or
visitors or any other persons lawfully in and upon the Land or Building, or
causes any impairment or reduction of the good will or reputation of the Land or
Building.

         2.7.3    Tenant shall not, without the prior consent of Landlord (which
consent shall not be unreasonably withheld, conditioned or delayed), use any
apparatus, machinery, device or equipment in or about the Premises which will
cause any substantial noise or vibration. Landlord acknowledges that Tenant uses
computers and related systems which may increase the normal consumption level of
electric power (which increased consumption of electrical power shall be paid by
Tenant as provided in Paragraph 3.4.9 hereof). If any of Tenant's apparatus,
machinery, devices or equipment should disturb the quiet enjoyment of any other
tenant in the Building, then Tenant shall provide, at its sole cost and expense,
adequate insulation or take other such action, including removing such
apparatus, machinery, devices or equipment, as may be necessary to eliminate the
disturbance. No food or beverage dispensing machines which require the deposit
of money shall be installed by Tenant in the Premises

                                       9

<PAGE>

without the prior written consent of Landlord, which consent shall not be
unreasonably withheld, conditioned or delayed provided such machines are solely
for the use of Tenant.

2.8      COMPLIANCE WITH GOVERNMENTAL REQUIREMENTS AND RULES AND REGULATIONS.
Tenant shall comply with all Governmental Requirements and Restrictions relating
to its use, occupancy and operation of the Premises and shall observe such
reasonable rules and regulations as may be adopted and published by Landlord
from time to time for the safety, care and cleanliness of the Premises and the
Building, and for the preservation of good order in the Building and for the
administration and management of the Building. Current Rules and Regulations are
attached to this Lease as Exhibit E. Notwithstanding the foregoing, Tenant shall
not be responsible for compliance with any Governmental Requirements and
Restrictions (except for Tenant's Pro Rata Share of Operating Expenses)
requiring (i) structural repairs or modifications to the Building (ii) repairs
or modifications to the utility or Building service equipment located outside of
and not exclusively serving the Premises or (iii) installation of new Building
service equipment, such as fire detection or suppression equipment, unless any
of such repairs, modifications, or installations referred to in the foregoing
clauses (i), (ii) and/or (iii) are required (a) due to Tenant's work,
alterations, or repairs in the Premises or Tenant's particular manner of use of
the Premises (as opposed to office use, generally), or (b) due to the act or
negligence of any of the Tenant or Tenant's Agents.

    SECTION 3: BASE RENT, ADDITIONAL RENT AND OTHER SUMS PAYABLE UNDER LEASE

3.1      PAYMENT OF RENTAL. Tenant agrees to pay Base Rent, Additional Rent and
any other sum due under this Lease to Landlord without demand, deduction,
credit, adjustment or offset of any kind or nature, in lawful money of the
United States when due under this Lease, at the offices of Manager at Manager's
Address, or to such other party or at such other place as Landlord may from time
to time designate in writing.

3.2      BASE RENT. On execution of this Lease, Tenant shall pay to Landlord the
amount specified in the definition of Prepaid Rent for the months specified in
the definition of that term. Tenant agrees to pay the monthly installments of
Base Rent to Landlord, without demand and in advance, on or before the first day
of each calendar month of the Lease Term. The monthly Base Rent installment for
any partial month at the beginning or end of the Lease Term shall be prorated.
Base Rent for any partial month at the beginning of the Lease Term shall be paid
by Tenant on the Commencement Date.

3.3      LEASE SECURITY PROVISIONS.

         3.3.1    On execution of this Lease, as security for the full and
faithful payment of all sums due under this Lease and the full and faithful
performance of every covenant and condition of this Lease to be performed by
Tenant, Tenant shall deliver a letter of credit in the amount of One Million Six
Hundred Thousand Dollars ($1,600,000.00) in favor of Landlord. The letter of
credit initially delivered pursuant to this paragraph and all substitutions,
replacements and renewals of it, must be consistent with and shall satisfy all
the requirements in the letter of credit criteria set forth on Exhibit F hereto.
The term "Letter of Credit" shall mean and refer to a letter of credit
conforming to this subparagraph. Tenant shall deliver the Letter of Credit to
Landlord simultaneously with Tenant's execution of this Lease. Landlord's
execution and delivery of this Lease to the Tenant shall be conclusive evidence
that Landlord has approved the form of the Letter of Credit.

         3.3.2    Landlord may draw on the Letter of Credit, in whole or in part
at Landlord's election, without advance notice to Tenant at any time or from
time to time on or after (a) the occurrence of any Event of Default, (b) if
Tenant, or anyone in possession of the Leased Premises through Tenant, holds
over after the expiration or earlier termination of this Lease, (c) Landlord is
given notice by the issuer of the Letter of Credit that it is terminating the
Letter of Credit, (d) a confirming bank gives notice to Landlord that it will
cease to act in that capacity, (e) the Letter of Credit expires on a specified
date by its terms and is not renewed or replaced at least forty-five (45) days
in advance of its expiration date or (f) to the extent permitted by law, in the
event any bankruptcy, insolvency, reorganization or any other debtor creditor
proceeding is instituted by or against Tenant.

         3.3.3    Landlord may apply any sum drawn on the Letter of Credit to
amounts owing to Landlord under this Lease in such order and priority as
Landlord elects in its absolute discretion. If any of the proceeds drawn on the
Letter of Credit are not applied immediately to sums owing to Landlord under
this Lease, Landlord may retain any such excess proceeds as a cash Lease
Security Deposit for application, at Lender's election, to future sums owing to
Landlord under this Lease, in such order and priority as

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<PAGE>

Landlord elects in its absolute discretion. Tenant shall, within fifteen (15)
days after Landlord's demand, restore the amount of the Letter of Credit drawn
so that the Letter of Credit is restored to the original amount of the Letter of
Credit. Within fifteen (15) days after Tenant has restored the Letter of Credit
to its original amount, Landlord shall return to Tenant the cash portion of the
Lease Security Deposit which Landlord has not applied against amounts due
hereunder. If Tenant does not restore the Letter of Credit to its original
amount within the required time period, such non-restoration shall be considered
an Event of Default.

         3.3.4    Additionally, Landlord's draw and application of all or any
portion of the proceeds of the Letter of Credit shall not impair any other
rights or remedies provided under this Lease or under applicable law and shall
not be construed as a payment of liquidated damages. If Tenant shall have fully
complied with all of the covenants and conditions of this Lease, the Letter of
Credit shall be returned to Tenant or, if Landlord has drawn on the Letter of
Credit, the remaining proceeds of the Letter of Credit which are in excess of
sums due the Landlord shall be repaid to Tenant, without interest, within thirty
(30) Business Days after the expiration or termination of the Lease Term and
delivery of possession of the Leased Premises to Landlord in accordance with
this Lease.

         3.3.5    On any request by Landlord made during the Lease Term, Tenant
shall cooperate in accomplishing any reasonable modification of the Letter of
Credit requested by Landlord; provided, however, that no such modification shall
increase Tenant's financial liability under the Letter of Credit. If the Letter
of Credit should be lost, mutilated, stolen or destroyed, Tenant shall cooperate
in obtaining the issuance of a replacement; provided, however, that Tenant shall
not be required to assume any additional financial liability or execute any
indemnity.

         3.3.6    Tenant shall not assign or grant any security interest in the
Letter of Credit and any attempt to do so shall be void and of no effect.

         3.3.7    In the event of a sale or transfer of Landlord's estate or
interest in the Land and Building, Landlord shall have the right to transfer the
Letter of Credit to the vendee or the transferee, Tenant shall pay any transfer
fees charged by the issuing bank and Landlord shall thereafter be considered
released by Tenant from all liability for the return of the Letter of Credit,
provided that such transferee assumes the Landlord's obligations hereunder with
respect to the Lease Security Deposit. Tenant shall cooperate in effecting such
transfer.

         3.3.8    No mortgagee or purchaser of any or all of the Building at any
foreclosure proceeding brought under the provisions of any mortgage shall
(regardless of whether the Lease is at the time in question subordinated to the
lien of any mortgage) be liable to Tenant or any other person for any or all
amounts drawn against the Letter of Credit or any other or additional lease
security deposit or other payment made by Tenant under the provisions of this
Lease), unless Landlord has actually delivered it in cash to such mortgagee or
purchaser, as the case may be.

         3.3.9    Notwithstanding any provision of this Section 3.3 to the
contrary, the amount which Landlord may draw under the Letter of Credit shall be
reduced (each a "Reduction" and collectively `Reductions") by one dollar for
each dollar of Base Rent actually paid under this Lease until the amount which
Landlord may draw has been reduced to Eight Hundred Thousand Dollars
($800,000.00), provided that on each day that such Base Rent is paid (i) the
Lease is in full force and effect, (ii) no Event of Default exists, (iii) No
Event of Default has occurred, and (iv) Tenant has not assigned this Lease nor
sublet more than twenty-five percent (25%) of the Premises (the foregoing items
(i) through (iv) are hereinafter collectively referred to as the "Reduction
Conditions"). If, on any date that Base Rent is due hereunder, the amount which
Landlord may draw under the Letter of Credit shall not be reduced because one or
more of the Reduction Conditions is not satisfied on such date, the amount which
Landlord may draw under the Letter of Credit shall not be reduced on any
subsequent date. In no event shall the amount which Landlord may draw under the
Letter of Credit be reduced to less than Eight Hundred Thousand Dollars
($800,000.00). At any time and from time to time (but not more often than once
every sixty (60) days), following any one or more Reductions as provided above,
Tenant may replace and/or amend the Letter of Credit to reduce the amount
thereof to the amount then required hereunder, provided that in no event may the
amount of the Letter of Credit be reduced below Eight Hundred Thousand Dollars
($800,000.00). Any replacement or amendment to the Letter of Credit shall
satisfy all of the requirements of this Paragraph 3.3.

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3.4      ADDITIONAL RENT. Definitions of certain terms used in this paragraph
are set forth in the last subparagraph of this paragraph entitled "Additional
Rent". Tenant agrees to pay to Landlord additional rent as computed in this
paragraph (individually and collectively the "Additional Rent"):

         3.4.1    ESTIMATED OPERATING COSTS. Tenant shall pay to Landlord as
Additional Rent one-twelfth (1/12) of the amount, if any, by which the Estimated
Operating Costs Allocable to the Premises exceeds the Base Amount Allocable to
the Premises. This sum shall be paid in advance on or before the first day of
each calendar month of the Lease Term. Landlord shall furnish Tenant a written
statement of Estimated Operating Costs Allocable to the Premises in advance of
the commencement of each Year. If such written statement is furnished after the
commencement of the Year (or as to the first Year during the Lease Term, after
the Commencement Date), Tenant shall also make a retroactive lump-sum payment to
Landlord equal to the monthly payment amount multiplied by the number of months
during the Year (or as to the first Year during the Lease Term, after the
Commencement Date) for which no payment was paid. Notwithstanding the foregoing,
Landlord reserves the right, from time to time during each Year, to revise the
Estimated Operating Costs Allocable to the Premises and upon notice to Tenant of
such revision, Tenant shall adjust its payment to Landlord under this
subparagraph 3.4.1 accordingly.

         3.4.2    ACTUAL COSTS. After the close of each Year, Landlord shall
deliver to Tenant a written statement setting forth the Operating Costs
Allocable to the Premises during the preceding Year which includes a line item
for each of the major categories of such expenses. If such Operating Costs
Allocable to the Premises for any Year exceed the Estimated Operating Costs
Allocable to the Premises paid by Tenant to Landlord pursuant to subparagraph
3.4.1 for such Year, Tenant shall pay the amount of such excess to Landlord
within twenty (20) Business Days after receipt of such statement by Tenant. If
such statement shows the Operating Costs Allocable to the Premises to be less
than the Estimated Operating Costs Allocable to the Premises paid by Tenant to
Landlord pursuant to subparagraph 3.4.1, then the amount of such overpayment
shall be paid by Landlord to Tenant within twenty (20) Business Days following
the date of such statement or, at Landlord's option, shall be credited towards
the installment(s) of Additional Rent next coming due from Tenant.

         3.4.3    DETERMINATION. The determination of Operating Costs Allocable
to the Premises shall be made by Landlord in accordance with the terms hereof.

         3.4.4    OPERATING COST AUDIT. Landlord shall maintain records
concerning estimated and actual Operating Costs Allocable to the Premises for no
less than twelve (12) months following the period covered by the statement or
statements furnished Tenant, after which time Landlord may dispose of such
records. Provided that there has not been an Event of Default, Tenant may, at
Tenant's sole cost and expense, cause a Qualified Person (defined below) to
inspect Landlord's records. Such inspection, if any, shall be conducted no more
than once each Year, during Landlord's normal business hours within ninety (90)
calendar days after receipt of Landlord's written statement of Operating Costs
Allocable to the Premises for the previous year, upon first furnishing Landlord
at least twenty (20) calendar days prior written notice. Any errors disclosed by
the review shall be promptly corrected by Landlord; provided, however, that if
Landlord disagrees with any such claimed errors, Landlord shall have the right
to cause another review to be made by an auditor of Landlord's choice. In the
event the results of the review of records (taking into account, if applicable,
the results of any additional review caused by Landlord) reveal that Tenant has
overpaid obligations for a preceding period, the amount of such overpayment
shall be credited against Tenant's subsequent installment of Base Rent,
Additional Rent or other payments due to Landlord under the Lease. In the event
that such results show that Tenant has underpaid its obligations for a preceding
period, the amount of such underpayment shall be paid by Tenant to Landlord with
the next succeeding installment obligation of estimated Operating Costs
Allocable to the Premises. If the actual Operating Costs Allocable to the
Premises for any given Year were improperly computed and if the actual Operating
Costs Allocable to the Premises are overstated by more than five percent (5%),
Landlord shall reimburse Tenant for the cost of its audit.

         3.4.5    END OF TERM. If this Lease shall terminate on a day other than
the last day of a Year, (a) Landlord shall estimate the Operating Costs
Allocable to the Premises and Property Taxes Allocable to the Premises for such
Year predicated on the most recent reliable information available to Landlord;
(b) the amount determined under clause (a) of this sentence shall be prorated by
multiplying such amount by a fraction, the numerator of which is the number of
days within the Lease Term in such Year and the denominator of which is 365; (c)
the Operating Costs Base Amount Allocable to the Premises shall be prorated in
the manner described in clause (b); (d) the clause (c) amount (i.e., the
prorated Operating Costs Base Amount Allocable to the Premises) shall be
deducted from the clause (b) amount (i.e., the

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<PAGE>

prorated Operating Costs Allocable to the Premises); (e) if the clause (d)
amount exceeds the Estimated Operating Costs Allocable to the Premises paid by
Tenant for the last Year in the Lease Term, then Tenant shall pay the excess to
Landlord within ten (10) Business Days after Landlord's delivery to Tenant of a
statement for such excess; and (f) if the Estimated Operating Costs Allocable to
the Premises paid by Tenant for the last Year in the Lease Term exceeds the
clause (d) amount, then Landlord shall refund to Tenant the excess within the
ten (10) Business Day period described in clause (e) if Tenant is not then in
default of any of its obligations under this Lease. Landlord's and Tenant's
obligations under this paragraph shall survive the expiration or other
termination of this Lease.

         3.4.6    DEFINITIONS. Each underlined term in this subparagraph shall
have the meaning set forth next to that underlined term:

         OPERATING COSTS BASE AMOUNT ALLOCABLE TO THE PREMISES: The Operating
         Costs Allocable to the Premises for the year beginning January 1, 2005
         and ending December 31, 2005 (the "Base Year").

         ESTIMATED OPERATING COSTS ALLOCABLE TO THE PREMISES: Landlord's written
         estimate of Operating Costs Allocable to the Premises for a Year to be
         given by Landlord to Tenant pursuant to subparagraph 3.4.1.

         OPERATING COSTS (NET OF PROPERTY TAXES): All expenses paid or incurred
         by Landlord for maintaining, operating, owning and repairing any or all
         of the Land, Building, Premises, related improvements, and the personal
         property used in conjunction with such Land, Building, Premises and
         related improvements, except for Property Taxes. Included are all
         expenses paid or incurred by Landlord for: (a) utilities, including
         electricity, water, gas, sewers, fire sprinkler charges, refuse
         collection, Telecommunication Services, cable television, steam, heat,
         cooling or any other similar service and which are not payable directly
         by tenants in the Building; (b) supplies; (c) cleaning, painting and
         janitorial services (including window washing), landscaping and
         landscaping maintenance (including irrigating, trimming, mowing,
         fertilizing, seeding and replacing plants), snow removal and other
         services; (d) security services, if any; (e) insurance premiums and
         applicable insurance deductible payments by Landlord; (f) management
         fees not exceeding prevailing market rates for comparable first class
         properties in the greater Burlington, Massachusetts area (and, for
         purposes hereof, Tenant shall have the burden of proving the extent (if
         any) to which such fees are in excess of such market rates); (g)
         compensation (including employment taxes and fringe benefits if paid,
         directly or indirectly, by Landlord) of all persons and business
         organizations who perform duties in connection with any service,
         repair, maintenance, replacement or improvement or other work included
         in this subparagraph; (h) license, permit and inspection fees; (i)
         assessments and special assessments due to deed restrictions,
         declarations or owners associations or other means of allocating costs
         of a larger tract of which the Land is a part; (j) rental of any
         machinery or equipment; (k) audit fees and accounting services related
         to the Building, and charges for the computation of the rents and
         charges payable by tenants in the Building (but only to the extent the
         cost of such fees and services are in addition to the cost of the
         management fee); (l) the cost of repairs or replacements; (m) charges
         under maintenance and service contracts; (n) legal fees and other
         expenses of legal or other dispute resolution proceedings; (o)
         maintenance and repair of the roof and roof membranes, (p) costs
         incurred by Landlord to increase the efficiency of any electrical,
         mechanical or other system servicing the Building or the Land; (q)
         costs incurred by Landlord for compliance with any and all Governmental
         Requirements, including Access Laws, but excluding any cost
         attributable to the Building's not being in compliance with such
         Governmental Requirements on the date hereof; (r) elevator service and
         repair, if any; (s) business taxes and license fees; (t) an appropriate
         share of the cost of operating, maintaining, repairing and replacing
         any common areas and facilities made available to Tenant which are not
         located on the Land but are located within the Park, including, without
         limitation, the exercise facility (hereinafter defined as the Building
         500 Fitness Center) presently located at 25 Corporate Drive in Building
         500, which costs shall be allocated to all buildings in the Park on a
         pro rata basis based upon each such building's total rentable square
         footage; (u) an appropriate share of the cost of maintaining and
         repairing the Monument Sign, which costs shall be allocated to all
         buildings in the Park on a pro rata basis based upon each such
         building's total rentable square footage; (v) any other expense or
         charge which in accordance with generally accepted accounting and
         management principles would be considered an expense of maintaining,
         operating, owning or repairing the

                                       13

<PAGE>

         Building; and (w) the amortization of costs of capital improvements in
         accordance with the next sentence. Costs associated with capital
         improvements installed or constructed by Landlord other than in the
         initial construction of the Building, whether such were constructed or
         installed before or after the Commencement Date, shall be amortized
         with interest return at the Prime Rate plus two (2) percentage points
         over the estimated useful life of the capital improvement as determined
         by Landlord in accordance with generally accepted accounting principles
         and the annual amortization of principal and interest attributable to
         the Lease Term shall be an Operating Cost. The capital improvements
         referred to in the previous sentence shall include: replacement of roof
         structure and roof membranes; exterior painting; parking area
         resurfacing, resealing and restriping parking areas and driveways and
         upgrading Building common systems and facilities (including HVAC
         systems, and if owned by Landlord, Telecommunication Facilities), but
         shall not include the initial cost of construction of any addition
         hereafter made to the Building or the initial cost of construction of
         any additional building not currently on the Land.

         EXCLUSIONS FROM OPERATING COSTS: Operating Costs shall not include any
         of the following: ground rent; interest and amortization of funds
         borrowed by Landlord for items other than capital improvements provided
         for in the definition of Operating Costs (net of Property Taxes) or
         elsewhere in this Lease; leasing commissions and advertising and space
         planning expenses incurred in procuring tenants; and salaries, wages,
         or other compensation paid to officers or executives of Landlord in
         their capacities as officers and executives, the cost of any additions
         or expansions to the common areas or the Building (excluding the cost
         of furniture, fixtures and equipment for any such additions or
         expansions, which cost shall be included in Operating Costs); any
         reserves for future expenditures not yet incurred; costs incurred by
         Landlord for repair or restoration in the case of a casualty or taking
         to the extent that Landlord is reimbursed by insurance or condemnation
         proceeds (or would have been reimbursed had Landlord carried the
         insurance required to be carried hereunder); repair and related costs,
         including permit, license and inspection costs incurred with respect to
         the installation of improvements made for other tenants or occupants or
         incurred in renovating or otherwise improving, decorating, painting or
         redecorating vacant space for other tenants or occupants; attorneys'
         fees, leasing commissions and other costs and expenses incurred in
         connection with negotiations or disputes with present or prospective
         tenants or other occupants of the Building; expenses in connection with
         services or benefits offered to other tenants which are not offered to
         Tenant; costs incurred by Landlord due to the gross negligence or
         willful misconduct of Landlord or its agents, contractors and
         employees; fees, overhead and profit increment paid to Landlord or to
         subsidiaries or affiliates of Landlord for services to the extent the
         same exceeds the market rate for such services rendered by other
         first-class, unaffiliated third parties on a competitive basis (and,
         for purposes hereof, Tenant shall have the burden of proving the extent
         (if any) by which any such fee is above market based upon comparable
         first class properties in the Burlington, Massachusetts area); electric
         power and any other utility costs for which any tenant or occupant
         directly contracts with the local public service company; costs
         incurred to comply with laws relating to the removal of Hazardous
         Substances which were present in the Building or on the Land prior to
         the date of this Lease (and, for purposes hereof, Tenant shall have the
         burden of proving that such Hazardous Substances were present in the
         Building or on the Land prior to the date of this Lease), and were of
         such a nature that a federal, state or municipal governmental
         authority, if it had then had knowledge of the presence of such
         hazardous material, in the state, and under the conditions that it then
         existed in the Building or on the Land, would have then required the
         removal of such Hazardous Substances or other remedial or containment
         action with respect thereto; and costs incurred to remove, remedy,
         contain, or treat Hazardous Substances, which Hazardous Substances are
         brought into the Building or onto the Land after the date hereof by
         Landlord or Landlord's Agents and are of such a nature, at that time,
         that a federal, state or municipal governmental authority, if it had
         then had knowledge of the presence of such Hazardous Substances, in the
         state, and under the conditions, that it then exists in the Building or
         on the Land, would have then required the removal of such Hazardous
         Substances or other remedial or containment action with respect
         thereto; any charges for depreciation of the Building; and any charge
         for Landlord's income taxes, excess profit taxes, or franchise taxes or
         related to a sale or transfer of the Building or any interest therein.

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<PAGE>

         GROSS-UP PROVISION: If less than ninety-five percent (95%) of the net
         rentable area of the Building is occupied by tenants at all times
         during any Year (including the Base Year), then Operating Costs for
         such Year may include all additional costs and expenses that Landlord
         reasonably determines would have been incurred had ninety-five percent
         (95%) of the Building been occupied at all times during such Year by
         tenants. The extrapolation of Operating Costs provided for herein shall
         be performed by appropriately adjusting the costs of those components
         of Operating Costs that fluctuate as a result of changes in the level
         of occupancy in the Building.

         OPERATING COSTS ALLOCABLE TO THE PREMISES: The product of Tenant's Pro
         Rata Share times Operating Costs (net of Property Taxes).

         QUALIFIED PERSON: This means an accountant or other person experienced
         in accounting for income and expenses of office projects.

         PROPERTY TAX BASE AMOUNT: Tenant's Pro Rata Share of the Property Taxes
         payable for the fiscal tax year 2005 (beginning July 1, 2004 and ending
         June 30, 2005).

         PROPERTY TAXES ALLOCABLE TO THE PREMISES: Tenant's Pro Rata Share of
         Property Taxes.

         3.4.7    PROPERTY TAX ESCALATION. In addition to the payments required
by the previous subparagraphs of this paragraph, Tenant shall pay as Additional
Rent to Landlord one-twelfth (1/12) of the amount, if any, by which (a)
Landlord's estimate of the Property Taxes Allocable to the Premises for the
current tax year exceeds the Property Tax Base Amount. This sum shall be paid in
advance on or before the first day of each calendar month of the Lease Term.
After the close of each tax year during the Lease Term, Landlord shall deliver
to Tenant a written statement setting forth (1) the actual Property Taxes
Allocable to the Premises for the preceding tax year, (2) the difference between
the amount referred to in clause (1) and the Property Tax Base Amount and (3)
the differential between the amount referred to in clause (2) and the sum of the
tentative monthly payments toward such amount made by Tenant. If the
differential referred to in clause (3) of the previous sentence represents an
underpayment by Tenant, such differential shall be paid to Landlord within
twenty (20) Business Days after delivery of Landlord's written statement to
Tenant; if such differential represents an overpayment by Tenant, Landlord
shall, at its option, either credit such overpayment to the installment(s) of
Additional Rent next coming due from Tenant or refund such overpayment to Tenant
within twenty (20) Business Days after Tenant's concurrence in the amount due as
a refund. If the Lease Term begins or ends on a day other than the beginning or
end of a tax year, the amount due as described in clause (2) of this
subparagraph shall be prorated on a per diem basis with reference to the tax
year. The provisions of this subparagraph shall survive the expiration or other
termination of this Lease.

         3.4.8    ABATEMENT. Provided that no Event of Default has theretofore
occurred and further provided that Tenant or a permitted assignee is itself
occupying the entire Initial Premises or at least sixty (60%) of the rentable
area of the Building, Tenant may seek an abatement of Property Taxes if Landlord
shall fail to do so within thirty (30) days after request by Tenant. In such
case, Tenant may do so in the name of the Landlord but at the sole cost and
expense of Tenant. Landlord agrees, at no cost or expense to Landlord, to
cooperate with Tenant in connection therewith. All reasonable costs and expenses
incurred by Tenant (including reasonable attorney's and appraiser's fees) in
obtaining any refund shall be recouped out of the first proceeds of any such
abatement procured and the amount so recouped will be excluded from the
abatement adjustment. In the event that Tenant is successful, the property tax
escalation shall be adjusted retroactively. Notwithstanding the foregoing or
anything herein to the contrary, if Tenant elects to seek an abatement and such
action results in an increase in the Property Taxes, Tenant shall be pay one
hundred percent (100%) of such increase for the first twelve (12) months that
such increase is in effect.

         3.4.9    TENANT'S COSTS. Tenant agrees to reimburse or pay Landlord
within twenty (20) Business Days after invoice from Landlord for (a) any
cleaning expenses incurred by Landlord, including carpet cleaning, garbage and
trash removal expenses, over and above the normal cleaning provided by Landlord,
if any, or due to the presence of a lunchroom or kitchen which serves or
provides prepared foods, (b) any expense incurred by Landlord for usage in the
Premises of heating, ventilating and air conditioning services, elevator
services, electricity, water, janitorial services, or any other services or
utilities over and above the normal usage for the Premises (including the
potential above normal usage of electrical power disclosed by Tenant in
Paragraph 2.7.3 hereof), (c) any expense incurred by Landlord relating to or
arising out of the usage by Tenant or Tenant's Agents of the public or common
areas of the Building or Land, or any of the equipment contained therein, which
usage is over and above the normal usage for such public or common areas or
equipment, and (d) any other direct expense incurred by

                                       15

<PAGE>

Landlord on Tenant's behalf in accordance with the terms hereof and/or after a
default by Tenant hereunder. Landlord reserves the right to install and activate
separate metering (or check metering) of electricity, water or other utilities
to the Premises, and Tenant agrees to reimburse or pay Landlord within twenty
(20) Business Days after invoice from Landlord for all actual out-of-pocket
costs of such separate metering (or check metering), in which case the Operating
Costs Base Amount Allocable to the Premises and Operating Costs shall be
adjusted accordingly.

         3.4.10   PAYMENTS DEEMED ADDITIONAL RENT. Any sums payable under this
Lease pursuant to this paragraph or otherwise shall be Additional Rent and, in
the event of nonpayment of such sums, Landlord shall have the same rights and
remedies with respect to such nonpayment as it has with respect to nonpayment of
the Base Rent due under this Lease.

3.5      UTILITIES

         3.5.1    Subject to paragraph 3.5.4 hereof, Landlord shall have the
right from time to time to select the company or companies providing
electricity, gas, fuel, one or more categories of Telecommunication Services and
any other utility services to the Building. Subject to the terms and conditions
hereof (including, without limitation, paragraphs 3.5.2 and 3.5.3) and the
provision of such services to the Building by local utility companies, Landlord
shall provide water, sewer, electricity and HVAC to the Premises. With the
exception of water, sewer, electricity and HVAC, Tenant shall contract directly
and pay for all utilities used on or from the Premises together with any taxes,
penalties, surcharges or similar charges relating to such utilities. If any such
service is not separately metered to the Premises or is not otherwise separately
accounted for and billed to Tenant, the cost therefor shall be an Operating Cost
under this Lease, provided that the cost of electric current for lights and
convenience outlets shall be billed by Landlord to Tenant separately from, and
in addition to, Operating Costs. Landlord estimates that the present cost of
electric current for lights and convenience outlets (exclusive of any other
purposes) shall be One Dollar ($1.00) per rentable square foot (which estimate
does not include the potential above normal usage of electrical power as
disclosed by Tenant in Paragraph 2,7.3 hereof). Landlord makes no warranty or
representation that such cost will not increase during the Lease Term due to
increases in electric rates and/or electricity consumption, as the case may be.

         3.5.2    Landlord shall in no case be liable or in any way be
responsible for damages or loss to Tenant arising from the failure of,
diminution of or interruption in electrical power, natural gas, fuel,
Telecommunication Services, sewer, water, or garbage collection services, other
utility service or building service of any kind to the Premises, unless such
interruption in, deprivation of or reduction of any such service was caused by
the gross negligence or willful misconduct of Landlord, its agents or
contractors or by a failure in facilities, equipment or systems in the
Landlord's ownership and, in any event, to the extent in Landlord's control,
Landlord agrees to use reasonable efforts to restore any services which have
been interrupted. To the extent that Landlord bears any responsibility for any
such interruption, deprivation or reduction in utility or building services to
the Premises, Landlord's responsibility and Tenant's remedy shall be limited to
an abatement in Base Rent for the period beginning with (a) the day which is
five (5) Business Days after the date on which Tenant delivers notice to
Landlord of such interruption, deprivation or reduction and that Tenant is being
deprived of all reasonable use of the Premises and ending on (b) the date such
interruption, deprivation or reduction which is Landlord's responsibility is not
causing Tenant to be deprived of all reasonable use of the Premises.

         3.5.3    Subject to the terms and conditions hereof (including, without
limitation, Paragraph 3.5.2) and the provision of applicable utility services to
the Building by local utility companies, Landlord shall provide HVAC service to
the Premises Monday through Friday (excluding holidays) from 7:00 a.m. to 7:00
p.m. and Saturdays (excluding holidays) from 7:00 a.m. to 12:00 noon at such
temperatures and in such amounts as customarily and seasonally provided to
tenants occupying comparable space in first class office buildings in the
Burlington, Massachusetts area (but in any event subject to any applicable
Governmental Requirements). If Tenant shall require after-hours HVAC, Tenant may
request such service by notifying Landlord's Manager not later than 11:00 a.m.
of the day prior to the day on which such after-hours service shall be needed,
and not later than 2:00 p.m. on the Thursday preceding any weekend for which
such after-hours service shall be needed reasonably estimating the number of
hours required for such after-hours service; provided, however, that Landlord
shall use reasonable efforts to provide after-hours HVAC service to the Premises
on shorter notice if requested by Tenant but Landlord's failure to provide
after-hours service after such shorter notice shall not be a default hereunder.
Tenant shall pay for such additional HVAC service at Landlord's hourly rate in
effect from time to time and shall pay all charges therefor when and as billed
by Landlord. Landlord's hourly rate for such additional HVAC service shall be
Landlord's actual cost

                                       16

<PAGE>

thereof (including utility costs, labor charges, and depreciation of HVAC
equipment) as reasonably estimated by Landlord. Such charges shall be deemed
Additional Rent under the Lease.

         3.5.4    Tenant shall have the right to select the provider(s) of
Telecommunication Services to the Premises, provided, however, if such
provider(s) need to locate or install Telecommunication Facilities in, on or
about the Land or the Building, such location and installation shall be subject
to the following terms and conditions: (a) Tenant shall deliver to Landlord full
and complete plans and specifications for such Telecommunication Facilities,
which plans and specifications shall be subject to approval by Landlord which
approval shall not be unreasonably withheld or delayed; (b) none of the
installation, maintenance or use of such Telecommunication Facilities shall
interfere with (i) the operation of the Building or the remainder of the Park or
the rights of any tenant or occupant thereof or (ii) the Telecommunication
Services or Telecommunication Facilities of any other provider; (c) the
installation of such Telecommunication Facilities shall be subject to Landlord's
oversight and such reasonable procedures, regulations, controls and directions
as the Landlord may specify; (d) Tenant shall pay to Landlord all costs incurred
by Landlord for any architectural, engineering, supervisory and/or legal
services in connection with the location and installation of such
Telecommunication Facilities, including, without limitation, Landlord's review
of the plans and specifications for same; and (e) the contractors and/or
telecommunication companies location and installation of such Telecommunication
Facilities shall be subject to the same requirements as are applicable to Tenant
under Paragraph 4.5 with respect to Tenant Alterations.

3.6      HOLDOVER. Tenant is not authorized to hold over beyond the expiration
or earlier termination of the Lease Term. If Landlord consents to a holdover and
no other agreement is reached between Tenant and Landlord concerning the
duration and terms of the Holdover, Tenant's holdover shall be a month-to-month
tenancy. During such tenancy, Tenant shall pay to Landlord one hundred fifty
percent (150%) of the rate of Base Rent in effect on the expiration or
termination of the Lease Term plus all Additional Rent and other sums payable
under this Lease, and shall be bound by all of the other covenants and
conditions specified in this Lease, so far as applicable. If the Landlord does
not consent to the Tenant's remaining in possession, Landlord shall have all the
rights and remedies provided for by law and this Lease. The Base Rent applicable
for the period that Tenant wrongfully remains in possession shall in be
increased to twice the rate of Base Rent in effect on the expiration or
termination of the Lease Term.

3.7      LATE CHARGE: If Tenant fails to make any payment of Base Rent,
Additional Rent or other amount when due under this Lease, a late charge is
immediately due and payable by Tenant equal to five percent (5%) of the amount
of any such payment. Landlord and Tenant agree that this charge compensates
Landlord for the administrative costs caused by the delinquency. The parties
agree that Landlord's damage would be difficult to compute and the amount stated
in this paragraph represents a reasonable estimate of such damage. Assessment or
payment of the late charge contemplated in this paragraph shall not excuse or
cure any Event of Default or breach by Tenant under this Lease or impair any
other right or remedy provided under this Lease or under law.

3.8      DEFAULT RATE. Any Base Rent, Additional Rent or other sum payable under
this Lease which is not paid when due shall bear interest at a rate equal to the
lesser of: (a) the published prime or reference rate of Riggs Bank N.A., or such
other national banking institution designated by Landlord if such bank ceases to
publish such rate (the "Prime Rate"), then in effect, plus four (4) percentage
points, or (b) the maximum rate of interest per annum permitted by applicable
law (the "Default Rate"), but the payment of such interest shall not excuse or
cure any Event of Default or breach by Tenant under this Lease or impair any
other right or remedy provided under this Lease or under law.

                  SECTION 4: MANAGEMENT AND LEASING PROVISIONS

4.1      MAINTENANCE AND REPAIR BY LANDLORD.

         4.1.1    Subject to the paragraphs captioned "Damage or Destruction"
and "Condemnation", Landlord shall endeavor to maintain the public and common
areas of the Building, the roof, the floor slab, the structural elements of the
Building and the Building systems in good order, repair and condition subject to
reasonable wear and tear. Landlord shall make such repairs thereto as become
necessary after obtaining actual knowledge of the need for such repairs. Upon
request by Tenant, Landlord also shall be responsible for light bulb replacement
in the Premises. All repair costs shall be included in Operating Costs, except
for (a) damage occasioned by the act or omission of Tenant or Tenant's Agents,
which shall be paid for entirely by Tenant upon demand by Landlord, (b) damage
occasioned by the act

                                       17

<PAGE>

or omission of Landlord or Landlord's Agents, which shall be paid for entirely
by Landlord, and (c) replacement of bulbs in non-standard building lighting
fixtures, which shall be paid for entirely by Tenant upon demand by Landlord. In
the event any or all of the Building becomes in need of maintenance or repair
which Landlord is required to make under this Lease, Tenant shall immediately
give written notice to Landlord, and Landlord shall not be obligated in any way
to commence such maintenance or repairs until a reasonable time elapses after
Landlord's receipt of such notice.

         4.1.2    Landlord shall not be liable by reason of any injury to or
interference with Tenant/s business arising from the making of any repairs,
alterations, additions or improvements in or to the Premises or the Building or
to any appurtenances or equipment therein; provided however, that Landlord
agrees to use reasonable efforts to minimize any interference with Tenant's
business. The foregoing shall not require Landlord to pay overtime rates to make
any such repairs, alterations, additions or improvements. There shall be no
abatement of rent because of such repairs, alterations, additions or
improvements or because of any delay by Landlord in making the same.

         4.1.3    Subject to the terms and conditions hereof (including, without
limitation, Paragraph 3.5.2) and the provision of applicable utility services to
the Building by local utility companies, Landlord shall also furnish (a)
automatic passenger elevators providing adequate service leading to the floor on
which the Premises are located; (b) janitorial services to the Premises in
accordance with the cleaning specifications attached hereto as Exhibit I; (iii)
hot and cold running water sufficient for drinking, lavatory, toilet and
ordinary cleaning purposes; (iv) electric current in reasonable amounts for the
Permitted Uses; (vi) extermination and pest control when reasonably necessary;
and (vii) maintenance to the common areas of the Building and the Land in a
manner comparable to other first class office buildings in the greater
Burlington, Massachusetts area including, but not limited to, HVAC,
illumination, snow plowing, deicing, repairs, replacements, parking lot striping
and resurfacing and landscaping. The costs of all such services shall be
included in Operating Costs.

         4.1.4    Landlord shall operate, or cause to be operated, a self
bussing, cafeteria with food products and non-alcoholic beverages on the first
floor of the Building (the "Building Cafeteria") during the hours of 7:00 a.m.
to 3:00 p.m. Monday through Friday (excluding holidays). The Building Cafeteria
shall have a minimum of fifty-four (54) seats. Landlord shall be solely
responsible to provide, or cause to be provided, all equipment, supplies, food
and other items required for the operation of the Building Cafeteria. The
Building Cafeteria shall offer breakfast and lunch, and snack service. Menu
offerings shall include, but not be limited to, soups, hot entrees, vegetables,
made to order cold sandwiches, grilled items, pizza, pre-made salads, salad bar,
desserts, hot deli items, and hot and cold beverages. The Building Cafeteria
shall be operated, in all respects, in accordance with standards at least equal
to those of other similar cafeterias located in first class office buildings in
the greater Burlington, Massachusetts area. Tenant acknowledges that (a) there
shall be no on-site cooking in the Building Cafeteria, (b) all hot entrees and
other hot items will be prepared offsite at the cafeteria (the "Building 500
Cafeteria") located in the Park at 25 Corporate Drive and that such items will
be delivered to the Building Cafeteria and maintained therein in warmers.

         4.1.5    In addition to the above-required Building Cafeteria service
operations, Landlord shall cause the operator (the "Cafeteria Operator") of the
Building Cafeteria and/or the Building 500 Cafeteria to provide catering
services on a reservation or as ordered basis in accordance with standards that
are consistent with a first class office building in the greater Burlington,
Massachusetts area. Such catering services shall include (i) simple coffee
services to full service dinners, (ii) coffee, muffins, bagels, and similar
foods for breakfast, and sandwiches and drinks for lunch, (iii) limited
pre-plated hot foods such as egg and breakfast meat sandwiches in the morning
and hot entrees and sandwiches for the luncheon service, (iv) after hours
functions, and (v) delivery and setup to Tenant's conference rooms and offices
and retrieval and cleanup. Tenant shall contract directly with the Cafeteria
Operator to furnish such services. Landlord shall have no liability or
responsibility for the acts or omissions of the Cafeteria Operator.

         4.1.6    During the Lease Term, Landlord shall provide at 25 Corporate
Drive exercise facilities (the "Building 500 Fitness Center") which shall
include separate men's' and women's' locker rooms and showers, and a reasonable
selection of exercise equipment and machines, sufficient to provide services to
the employees of the tenants in the Park, including Tenant. The exercise
facilities provided in the Building 500 Fitness Center shall be equal in quality
to the exercise facilities located in the Building 500 Fitness Center as of the
date of this Lease. The Building 500 Fitness Center shall be open from 7:00 a.m.
to 9:00 p.m. seven (7) days a week. The Building 500 Fitness Center shall not be
staffed, nor shall towel

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<PAGE>

services be provided. During the Lease Term, Tenant and its employees shall have
the nonexclusive right to use the Building 500 Fitness Center in common with
Landlord and all others to whom Landlord has granted or may hereafter grant
rights, provided that any person's use of the Building 500 Fitness Center shall
be at such person's own risk and shall be conditioned on such person signing a
waiver of liability in such form as the Landlord from time to time may require.
Tenant's use of such common areas shall be subject to such reasonable
regulations as Landlord may from time to time impose and the rights of Landlord
set forth herein.

4.2      MAINTENANCE AND REPAIR BY TENANT.

         4.2.1    Except as is expressly set forth as Landlord's responsibility
pursuant to the paragraph captioned "Maintenance and Repair by Landlord" and
subject to the paragraphs captioned "Damage and Destruction" and "Condemnation,"
Tenant shall at Tenant's sole cost and expense keep, clean and maintain the
Premises in good condition and repair, including interior painting, cleaning of
the interior side of all exterior glass, plumbing and utility fixtures and
installations, carpets and floor coverings, all interior wall surfaces and
coverings (including tile and paneling), window replacement, exterior and
interior doors, roof penetrations and membranes in connection with any Tenant
installations on the roof, and interior preventative maintenance. If Tenant
fails to maintain or repair the Premises in accordance with this paragraph, then
Landlord may, but shall not be required to, enter the Premises upon two (2)
Business Days prior written notice to Tenant (or immediately without any notice
in the case of an emergency) to perform such maintenance or repair at Tenant's
sole cost and expense. Tenant shall pay to Landlord the reasonable cost of such
maintenance or repair plus a fifteen percent (15%) administration fee within ten
(10) Business Days of written demand from Landlord.

         4.2.2    Without limiting the generality of paragraph 4.2.1 hereof,
Tenant shall be responsible at Tenant's sole cost and expense for the
maintenance, repair and/or replacement of any special heating, ventilating, air
conditioning, plumbing, electrical or other systems and fixtures installed
solely to service the Premises, whether installed or paid for by Landlord or
Tenant.

4.3      COMMON AREAS/SECURITY.

         4.3.1    The common areas of the Building shall be subject to
Landlord's sole management and control. Without limiting the generality of the
immediately preceding sentence, Landlord reserves the exclusive right as it
deems necessary or desirable to install, construct, remove, maintain and operate
lighting systems, facilities, improvements, equipment, Telecommunication
Facilities and signs on, in or to all parts of the common areas; change the
number, size, height, layout, or locations of walks, driveways and truckways or
parking areas now or later forming a part of the Land or Building; make
alterations or additions to the Building or common area; close temporarily all
or any portion of the common areas to make repairs, changes or to avoid public
dedication; grant easements to which the Land will be subject; replat,
subdivide, or make other changes to the Land; place or relocate or cause to be
placed or located utility lines and Telecommunication Facilities through, over
or under the Land and Building; and use or permit the use of all or any portion
of the roof of the Building. Landlord reserves the right to relocate parking
areas and driveways (if any) and to build additional improvements in the common
areas. Notwithstanding anything to the contrary herein, except in the case of an
emergency, Landlord shall not undertake any action which would materially
adversely affect Tenant's access to the Premises or materially interfere with or
reduce Tenant's parking.

         4.3.2    Landlord has no duty or obligation to provide any security
services in, on or around the Premises, Land or Building, and Tenant recognizes
that security services, if any, provided by Landlord will be for the sole
benefit of Landlord and the protection of Landlord's property and under no
circumstances shall Landlord be responsible for, and Tenant waives any rights
with respect to, Landlord providing security or other protection for Tenant or
Tenant's Agents or property in, on or about the Premises, Land or Building.
Subject to Landlord's prior approval (which approval shall not be unreasonably
withheld, conditioned or delayed), Tenant may, at its sole cost and expense,
install, establish and maintain security services within the Premises; provided
that, such security services (including any apparatus, facilities, equipment or
people utilized in connection with the provision of such security services)
comply with the Governmental Requirements and shall not cause the Building to be
out of compliance with the Governmental Requirements. Notwithstanding the
foregoing, any such security services installed, established or maintained by
Tenant must not affect or impact any portion of the Building or the Land other
than the Premises and shall not in any way limit or interfere with Landlord's
ability to exercise its rights as provided in the paragraph captioned "Access".
Tenant's rights under this

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<PAGE>

subparagraph are subject to all the obligations, limitations and requirements as
set forth in the paragraphs captioned "Tenant Alterations" and "Tenant's Work
Performance".

4.4      TENANT ALTERATIONS. Tenant shall not make any alterations, additions or
improvements in or to the Premises, or make changes to locks on doors, or add,
disturb or in any way change any floor covering, wall covering, fixtures,
plumbing, wiring or Telecommunication Facilities (individually and collectively
"Tenant Alterations"), without first obtaining the consent of Landlord, which
consent shall not be unreasonably withheld, conditioned or delayed provided such
alterations, additions or improvements are entirely within the Premises and do
not impact any structural components of the Building or any building systems.
Notwithstanding the foregoing, Tenant may make interior non-structural
Alterations which do not affect any of the Building's mechanical, HVAC,
electrical, plumbing or other systems without the consent of the Landlord
provided that the aggregate cost of such Alterations does not exceed Fifty
Thousand Dollars ($50,000.00) ("Permitted Alterations") in any period of twelve
(12) consecutive calendar months. Tenant shall deliver to Landlord full and
complete plans and specifications for any proposed Tenant Alterations (including
Permitted Alterations). If consent by Landlord is required and given, all such
work shall be performed at Tenant's expense by Landlord or by Tenant at
Landlord's election. Tenant shall pay to Landlord all costs incurred by Landlord
for any architecture, engineering, supervisory and/or legal services in
connection with any Tenant Alterations, including, without limitation,
Landlord's review of the plans and specifications. Without limiting the
generality of the foregoing, Landlord may require Tenant (if Landlord has
elected to require Tenant to perform the Tenant Alterations), at Tenant's sole
cost and expense, to obtain and provide Landlord with proof of insurance
coverage and a payment and performance bond, in forms, amounts and by companies
acceptable to Landlord in Landlord's reasonable discretion. Should Tenant make
any alterations without Landlord's prior written consent, or without
satisfaction of any conditions established by Landlord, Landlord shall have the
right, in addition to and without limitation of any right or remedy Landlord may
have under this Lease, at law or in equity, to require Tenant to remove some or
all of Tenant Alterations, or at Landlord's election, Landlord may remove such
Tenant Alterations and restore the Premises at Tenant's expense. Nothing
contained in this paragraph or the paragraph captioned "Tenant's Work
Performance" shall be deemed a waiver of the provisions of the paragraph
captioned "Mechanic's Liens".

4.5      TENANT'S WORK PERFORMANCE. If Landlord elects to permit Tenant to
perform the Tenant Alterations, Landlord may, in its absolute discretion,
require that Tenant provide a payment and performance bond to cover the entire
work to be performed, which bond must be in form, amount and by a company
acceptable to Landlord. Any Tenant Alterations to be performed under this
paragraph shall be performed by contractors employed by Tenant under one or more
construction contracts, in form and content approved in advance in writing by
Landlord, which approval shall not be unreasonably withheld, conditioned or
delayed. In any event, approval shall include a requirement that the prime
contractor and the respective subcontractors of any tier performing the Tenant
Alterations: (a) be parties to, and bound by, a collective bargaining agreement
with a labor organization affiliated with the Building and Construction Trades
Council of the AFL-CIO applicable to the geographic area in which the Building
is located and to the trade or trades in which the work under the contract is to
be performed and (b) employ only members of such labor organizations to perform
work within their respective jurisdictions. Tenant's contractors, workers and
suppliers shall work in harmony with and not interfere with workers or
contractors of Landlord or other tenants of Landlord. If Tenant's contractors,
workers or suppliers do, in the opinion of Landlord, cause such disharmony or
interference, Landlord's consent to the continuation of such work may be
withdrawn upon written notice to Tenant. All Tenant Alterations shall be (1)
completed in accordance with the plans and specifications approved by Landlord;
(2) completed in accordance with all Governmental Requirements; (3) carried out
promptly in a good and workmanlike manner; (4) of all new materials; and (5)
free of defect in materials and workmanship. Tenant shall pay for all damage to
the Premises, Building and Land caused by Tenant or Tenant's Agents. Tenant
shall indemnify, defend and hold harmless Landlord and Landlord's Agents from
any Claims arising as a result of the Tenant Alterations or any defect in
design, material or workmanship of any Tenant Alterations.

4.6      SURRENDER OF POSSESSION. Tenant shall, at the expiration or earlier
termination of this Lease, surrender and deliver the Premises to Landlord in as
good condition as when received by Tenant from Landlord or as later improved,
reasonable use and wear and damage by casualty and taking by eminent domain (but
only to the extent Tenant is not obligated to repair such damage under
Paragraphs 4.9 and/or 4.10 hereof) excepted, and free from all tenancies or
occupancies by any person claiming by through or under Tenant.

                                       20

<PAGE>

4.7      REMOVAL OF PROPERTY. Upon expiration or earlier termination of this
Lease, Tenant may remove its personal property, trade fixtures, office supplies
and office furniture and equipment if (a) such items are readily moveable and
are not attached to the Premises, or if they are attached to the Premises,
Tenant complies with subsection (d) of this Paragraph 4.7; (b) such removal is
completed prior to the expiration or earlier termination of this Lease; (c) no
Event of Default exists at the time of such removal; and (d) Tenant immediately
repairs all damage caused by or resulting from such removal. All other property
in the Premises and any Tenant Alterations (including, wall-to-wall carpeting,
paneling, wall covering, lighting fixtures and apparatus or Telecommunication
Facilities or any other articles affixed to the floor, walls, ceiling or any
other part of the Premises or Building) shall become the property of Landlord
and shall remain upon and be surrendered with the Premises; provided, however,
at Landlord's sole election, Tenant shall be obligated, at its sole cost and
expense, to remove all (or such portion as Landlord shall designate) of the
Tenant Alterations (including Telecommunication Facilities), repair any damages
resulting from such removal and return the Premises to the same condition as
existed prior to such Tenant Alterations. Notwithstanding the foregoing, if
Tenant's submission of its plans and specifications to Landlord for approval of
any Tenant Alterations requiring Landlord's approval is accompanied by a written
request that Landlord identify any Tenant Alterations that Landlord may require
Tenant to remove upon the expiration or earlier termination of this Lease,
Landlord shall identify such Tenant Alterations (if any) by notice to Tenant
given at the time of Landlord's approval of such Tenant Alterations. Tenant
waives all rights to any payment or compensation for such Tenant Alterations
(including Telecommunication Facilities). If Tenant shall fail to remove any of
its property from the Premises, Building or Land at the expiration or earlier
termination of this Lease or when Landlord has the right of re-entry, Landlord
may, at its option, remove and store such property at Tenant's expense without
liability for loss of or damage to such property, such storage to be for the
account and at the expense of Tenant. Tenant shall pay all actual out-of -pocket
costs incurred by Landlord within five (5) Business Days after demand for such
payment. If Tenant fails to pay the cost of storing any such property, Landlord
may, at its option, after it has been stored for a period of twenty (20)
Business Days or more, sell or permit to be sold, any or all such property at
public or private sale (and Landlord may become a purchaser at such sale), in
such manner and at such times and places as Landlord in its sole discretion may
deem proper, without notice to Tenant, and Landlord shall apply the proceeds of
such sale: first, to the cost and expense of such sale, including reasonable
attorney's fees actually incurred; second, to the payment of the costs or
charges for storing any such property; third, to the payment of any other sums
of money which may then be or later become due Landlord from Tenant under this
Lease; and, fourth, the balance, if any, to Tenant.

4.8      ACCESS. Tenant shall permit Landlord and Landlord's Agents to enter
into the Premises at any reasonable times on at least one (1) Business Day's
notice (except in case of emergency in which case no notice shall be required
and entry may be at any time), for the purpose of inspecting the same or for the
purpose of repairing, altering or improving the Premises or the Building,
provided, however, that Landlord shall not have access to the Tenant's data
center in the Premises unless accompanied by an employee of Tenant (except in
case of emergency in which case Landlord may enter such data center without
being accompanied by an employee of Tenant) and Tenant agrees to use reasonable
efforts to make such employee available in response to Landlord's request. Any
repair, alteration or improvement to be performed by Landlord within the
Premises (i) shall be located, to the extent reasonably practicable, within the
ceiling plenum, the walls or floors, or within the chases, risers, ducts,
conduits, lines, shafts or similar concealed areas and, (ii) in all cases, to
the extent reasonably practicable, (1) shall be performed and installed at such
times and by such methods as will not materially interfere with Tenant's use of
the Premises (provided that Landlord shall not be required to pay overtime rates
to make any such repairs, alterations, or improvements), damage the appearance
thereof, or reduce the rentable area thereof (provided that any material
reduction in rentable area shall entitle Tenant to an equitable reduction of
rent), (2) shall be coordinated and scheduled with Tenant in order to
accommodate Tenant's reasonable business needs, and (3) shall be located where
practical and reasonably efficient, taking into account Tenant's use of the area
of the Premises affected thereby, and Tenant shall cooperate with Landlord in
connection therewith. Nothing contained in this paragraph shall be deemed to
impose any obligation upon Landlord not expressly stated elsewhere in this
Lease. When reasonably necessary, Landlord may temporarily close Building or
Land entrances, Building doors or other facilities, without liability to Tenant
by reason of such closure and without such action by Landlord being construed as
an eviction of Tenant or as relieving Tenant from the duty of observing or
performing any of the provisions of this Lease.

                                       21

<PAGE>

Unless such temporary closure is due to an emergency and/or Governmental
Requirements, Tenant shall be provided with reasonable alternative access to the
Land and/or Building (as applicable). Landlord shall have the right to enter the
Premises at any time during the Lease Term that an Event of Default exists and
at any time during the last twelve (12) months of the Lease Term for the purpose
of showing the Premises to prospective tenants and to erect on the Premises a
suitable sign indicating the Premises are available. Tenant shall give written
notice to Landlord at least twenty (20) Business Days prior to vacating the
Premises and shall arrange to meet with Landlord for a joint inspection of the
Premises prior to vacating. In the event of Tenant's failure to give such notice
or arrange such joint inspection, Landlord's inspection at or after Tenant's
vacating the Premises shall be conclusively deemed correct for purposes of
determining Tenant's responsibility for repairs and restoration. Landlord shall
not be liable for the consequences of admitting by passkey, or refusing to admit
to the Premises, Tenant or any of Tenant's Agents, or other persons claiming the
right of admittance.

4.9      DAMAGE OR DESTRUCTION.

         4.9.1    If the Premises are damaged by fire, earthquake or other
casualty, Tenant shall give immediate written notice thereof to Landlord unless
Tenant is aware that the Manager has Actual Knowledge (as hereinafter defined)
of such damage. As used herein, "Actual Knowledge" means and refers to the
actual knowledge of senior management of the Manager. If Landlord estimates that
the damage can be repaired in accordance with the then-existing Governmental
Requirements within one hundred-twenty (120) Business Days after Landlord is
notified by Tenant or the Manager obtains Actual Knowledge of such damage and if
there are sufficient insurance proceeds available to repair such damage, then
Landlord shall proceed with reasonable diligence to restore the Premises to
substantially the condition which existed prior to the damage and this Lease
shall not terminate. If, in Landlord's estimation, the damage cannot be repaired
within such one hundred-twenty (120) Business Day period or if there are
insufficient insurance proceeds available to repair such damage, Landlord,
within forty-five (45) Business Days after Landlord is notified by Tenant or the
Manager obtains Actual Knowledge of such damage, may elect in its absolute
discretion to either: (a) terminate this Lease or (b) restore the Premises to
substantially the condition which existed prior to the damage and this Lease
will continue. If Landlord elects to restore the Premises under this paragraph,
then Landlord shall use commercially reasonable efforts to proceed toward
completion of the restoration and (1) Landlord shall complete such restoration
within twelve (12) months after the earlier of the date Landlord is notified by
Tenant of such damage or the date that the Manager obtains Actual Knowledge of
such damage, (2) Tenant shall pay to Landlord, upon demand, Tenant's Pro Rata
Share of any applicable deductible amount specified under Landlord's insurance
and (3) notwithstanding anything to the contrary contained herein, Landlord
shall not be required to repair or restore Tenant Improvements, Tenant
Alterations (including Telecommunication Facilities), or any or all furniture,
fixtures, equipment, inventory, improvements or other property which was in or
about the Premises at the time of the damage and was not owned by Landlord. In
the case of damage to the Premises not caused by the negligence or other
tortuous acts of the Tenant which is of a nature or extent that (a) such damage
materially interferes Tenant's use of a portion (but not all) of the Premises
(such portion being referred to herein as the "Materially Affected Premises"),
Base Rent and Additional Rent otherwise payable hereunder shall be partially
abated by the amount thereof allocable to the Materially Affected Premises on a
per rentable square foot basis, for the period beginning on the date of such
casualty and ending on the earlier of (i) the date that Landlord has
substantially completed its repairs to the Materially Affected Premises and (ii)
the date that Tenant uses any portion of the Materially Affected Premises for
the conduct of its business, and (b) it is impracticable for the Tenant to carry
on its business in any of the Premises, all Base Rent and Additional Rent
otherwise payable hereunder shall be abated for the period beginning on the date
of such casualty and ending on the earlier of (i) the date that Landlord has
substantially completed its repairs to the Premises and (ii) the date that
Tenant uses any portion of the Premises for the conduct of its business. Except
for the abatement of rent if and to the extent provided herein, Tenant agrees to
look to the provider of Tenant's insurance for coverage for the loss of Tenant's
use of the Premises and any other related losses or damages incurred by Tenant
during any reconstruction period.

         4.9.2    If the Building is damaged by fire, earthquake or other
casualty and more than fifty percent (50%) of the Building is rendered
untenantable, without regard to whether the Premises are affected by such
damage, Landlord may in its absolute discretion and without limiting any other
options available to Landlord under this Lease or otherwise, elect to terminate
this Lease by notice in writing to Tenant within forty (40) Business Days after
the occurrence of such damage if Landlord is also

                                       22

<PAGE>

terminating the leases of other tenants in the Building who are similarly
situated to Tenant. Such notice shall be effective twenty (20) Business Days
after receipt by Tenant unless a later date is set forth in Landlord's notice.

         4.9.3    Notwithstanding anything contained in this Lease to the
contrary, if there is damage to the Premises or Building and the holder of any
indebtedness secured by a mortgage or deed of trust covering any such property
requires that the insurance proceeds be applied to such indebtedness or if the
insurance proceeds are otherwise inadequate to complete the repair of the
damages to the Premises, the Building or both, then Landlord shall have the
right to terminate this Lease by delivering written notice of termination to
Tenant within fifteen (15) Business Days after Landlord is notified of such
requirement.

         4.9.4    Notwithstanding the foregoing, if the Premises or the Building
are wholly or partially damaged or destroyed within the final twelve (12) months
of the Lease Term to such an extent that the cost of restoration would exceed
fifty percent (50%) of the replacement cost of the Premises and/or the Building
in its or their entirety at the time such damage or destruction occurs ,
Landlord may, at its option, elect to terminate this Lease upon written notice
to Tenant within thirty (30) days following such damage or destruction. Further,
notwithstanding the foregoing, if the Premises are wholly or partially damaged
or destroyed within the final two (2) years of the Lease Term to such an extent
that the cost of restoration would exceed fifty percent (50%) of the replacement
cost of the Premises in its entirety at the time such damage or destruction
occurs, then Tenant also may terminate this Lease upon written notice to
Landlord within thirty (30) days following such damage or destruction.

4.10     CONDEMNATION. If all of the Premises, or such portions of the Building
as may be required for the Tenant's reasonable use of the Premises, are taken by
eminent domain or by conveyance in lieu thereof, this Lease shall automatically
terminate as of the date the physical taking occurs, and all Base Rent,
Additional Rent and other sums payable under this Lease shall be paid to that
date. In case of taking of a part of the Premises or a portion of the Building
not required for the Tenant's reasonable use of the Premises, then this Lease
shall continue in full force and effect and the Base Rent shall be equitably
reduced based on the proportion by which the floor area of the Premises is
reduced, such reduction in Base Rent to be effective as of the date the physical
taking occurs. Additional Rent and all other sums payable under this Lease shall
not be abated but Tenant's Pro Rata Share may be redetermined as equitable under
the circumstances. Landlord reserves all rights to damages or awards for any
taking by eminent domain relating to the Premises, Building, Land and the
unexpired term of this Lease. Tenant assigns to Landlord any right Tenant may
have to such damages or award and Tenant shall make no claim against Landlord
for damages for termination of its leasehold interest or interference with
Tenant's business. Tenant shall have the right, however, to claim and recover
from the condemning authority compensation for any loss to which Tenant may be
entitled for Tenant's moving expenses or other relocation costs; provided that,
such expenses or costs may be claimed only if they are awarded separately in the
eminent domain proceedings and not as a part of the damages recoverable by
Landlord.

4.11     PARKING. Tenant shall have the nonexclusive privilege to use parking
spaces on the Land in common with other tenants of Landlord, but only in areas
reasonably designated by Landlord and only on a first-come-first-served basis.
Tenant's parking privileges shall be subject to the rules and regulations
relating to parking adopted by Landlord from time to time and uniformly applied
to all tenants of the Building. Landlord shall not have the right to grant
designated, reserved parking stalls to other tenants in the Building. In no
event shall the number of parking stalls used by Tenant and Tenant's Agents
exceed the number of stalls allocated to Tenant in the definition of the Parking
Ratio, provided, however, that nothing in this sentence shall be deemed to alter
the first-come-first-served basis of parking as provided in this paragraph 4.11.
Landlord makes no representations or warranties concerning the availability of
parking for Tenant's use at any time during the Term, except that Landlord shall
make available to Tenant on a first-come-first-served basis a sufficient number
of parking spaces to satisfy the number of spaces allocated to Tenant in the
definition of Parking Ratio. Landlord shall use reasonable efforts to monitor or
police the use of the parking or other common areas or to maintain the parking
ratio stated in this Lease.

4.12     INDEMNIFICATION.

         4.12.1   Tenant shall indemnify, defend and hold harmless Landlord and
Landlord's Agents from and against any and all Claims, arising in whole or in
part out of (a) the possession, use or occupancy of the Premises or the business
conducted in the Premises, (b) any act, omission or negligence of Tenant or
Tenant's Agents, or (c) any breach or default under this Lease by Tenant.
Notwithstanding anything to the contrary herein contained, Tenant shall not be
responsible for indemnifying Landlord for Claims to the extent caused by the
gross negligence or willful misconduct of Landlord or Landlord's Agents.

                                       23

<PAGE>

         4.12.2   Except as specified in the next sentence, neither Landlord nor
Landlord's Agents shall, to the extent permitted by law, have any liability to
Tenant, or to Tenant's Agents, for (1) any Claims arising out of any cause
whatsoever, including repair to any portion of the Premises; (2) interruption in
or interference with the use of the Premises or any equipment therein; (3) any
accident or damage resulting from any use or operation by Landlord, Tenant or
any person or entity of heating, cooling, electrical, sewerage or plumbing
equipment or apparatus or Telecommunication Facilities; (4) termination of this
Lease by reason of damage to the Premises or Building; (5) fire, robbery, theft,
vandalism, mysterious disappearance or a casualty of any kind or nature; (6)
actions of any other tenant of the Building or of any other person or entity;
(7) inability to furnish any service required of Landlord as specified in this
Lease; or (8) leakage in any part of the Premises or the Building from rain, ice
or snow, or from drains, pipes or plumbing fixtures in the Premises or the
Building. Landlord shall be responsible only for Claims arising solely out of
the gross negligence or willful misconduct of Landlord in failing to repair or
maintain the Building as required by this Lease after notice by Tenant as
required by the paragraph captioned "Maintenance and Repair by Landlord"; but in
no event shall Landlord's responsibility extend to any interruption to Tenant's
business or any indirect or consequential losses suffered by Tenant or Tenant's
Agents or extend beyond Landlord's responsibility as set forth in the paragraph
entitled "Utilities" when that paragraph is applicable. The obligations of this
paragraph shall be subject to the paragraph captioned "Waiver of Subrogation".

4.13     TENANT INSURANCE.

         4.13.1   Tenant shall, throughout the Lease Term, at its own expense,
keep and maintain in full force and effect the following policies, each of which
shall be endorsed as needed to provide that the insurance afforded by these
policies is primary and that all insurance carried by Landlord is strictly
excess and secondary and shall not contribute with Tenant's liability insurance:

                  (a)      A policy of commercial general liability insurance,
including a contractual liability endorsement covering Tenant's obligations
under the paragraph captioned "Indemnification", insuring against claims of
bodily injury and death or property damage or loss with a combined single limit
at the Commencement Date of this Lease of not less than Two Million Dollars
($2,000,000.00), which limit shall be reasonably increased during the Lease Term
at Landlord's request to reflect both increases in liability exposure arising
from inflation as well as from changing use of the Premises or changing legal
liability standards, which policy shall be payable on an "occurrence" rather
than a "claims made" basis, and which policy names Landlord, Kennedy Associates
Real Estate Counsel, Inc. (Landlord's investment advisor), Riggs & Company, a
division of Riggs Bank, NA, as Trustee of the Multi-Employer Property Trust, a
trust organized under 12 C.F.R. Section 9.18 (the beneficiary of the Landlord),
Manager and, at Landlord's request, Landlord's mortgage lender(s) and/or
trustee(s), as additional insureds;

                  (b)      A policy of extended property insurance (which is
commonly called "all risk") covering Tenant Improvements, Tenant Alterations
(including Telecommunication Facilities), and any and all furniture, fixtures,
equipment, inventory, improvements and other property in or about the Premises
which is not owned by Landlord, for one hundred percent (100%) of the then
current replacement cost of such property;

                  (c)      Business interruption insurance in an amount
sufficient to cover costs, damages, lost income, expenses, Base Rent, Additional
Rent and all other sums payable under this Lease, should any or all of the
Premises not be usable for a period of up to twelve (12) months;

                  (d)      A policy or worker's compensation insurance as
required by applicable law and employer's liability insurance with limits of no
less than One Million Dollars ($1,000,000.00); and

                  (e)      A policy of comprehensive automobile liability
insurance, including loading and unloading, and covering owned, non-owned and
hired vehicles, with limits of no less than One Million Dollars ($1,000,000.00)
per occurrence.

         4.13.2   All insurance policies required under this paragraph shall be
with companies reasonably approved by Landlord and each policy shall provide
that it is not subject to cancellation, lapse or reduction in coverage except
after thirty (30) days' written notice to Landlord and all parties required
hereunder to be named as additional insureds. Tenant shall deliver to Landlord
and, at Landlord's request, Landlord's mortgage lender(s) and all parties
required hereunder to be named as additional insureds, prior to the Commencement
Date and from time to time thereafter, certificates evidencing the existence and
amounts of all such policies.

         4.13.3   If Tenant fails to acquire or maintain any insurance or
provide any certificate required by this paragraph, Landlord may, but shall not
be required to, obtain such insurance or certificates and the

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costs associated with obtaining such insurance or certificates shall be payable
by Tenant to Landlord on demand.

4.14     LANDLORD'S INSURANCE. Landlord shall, throughout the Lease Term, keep
and maintain in full force and effect:

         4.14.1   A policy of commercial general liability insurance, insuring
against claims of bodily injury and death or property damage or loss with a
combined single limit at the Commencement Date of not less than Five Million
Dollars ($5,000,000.00), which policy shall be payable on an "occurrence" rather
than a "claims made" basis;

         4.14.2   A policy of extended property insurance (what is commonly
called "all risk") covering the Building and Landlord's personal property, if
any, located on the Land in the amount of one hundred percent (100%) of the then
current replacement value of such property; and

         4.14.3   Landlord may, but shall not be required to, maintain other
types of insurance as Landlord deems appropriate, including but not limited to,
property insurance coverage for earthquakes and floods in such amounts as
Landlord deems appropriate. Such policies may be "blanket" policies which cover
other properties owned by Landlord.

4.15     WAIVER OF SUBROGATION. Notwithstanding anything in this Lease to the
contrary, Landlord and Tenant hereby each waive and release the other from any
and all Claims or any loss or damage that may occur to the Land, Building,
Premises, or personal property located therein, by reason of fire or other
casualty regardless of cause or origin, including the negligence or misconduct
of Landlord, Tenant, Landlord's Agents or Tenant's Agents, but only to the
extent of the insurance proceeds paid to such releasor under its policies of
insurance or, if it fails to maintain the required policies, the insurance
proceeds that would have been paid to such releasor if it had maintained such
policies. Each party to this Lease shall promptly give to its insurance company
written notice of the mutual waivers contained in this subparagraph, and shall
cause its insurance policies to be properly endorsed, if necessary, to prevent
the invalidation of any insurance coverages by reason of the mutual waivers
contained in this subparagraph.

4.16     ASSIGNMENT AND SUBLETTING BY TENANT.

         4.16.1   Tenant shall not have the right to assign, transfer, mortgage
or encumber this Lease in whole or in part, nor sublet the whole or any part of
the Premises, nor allow the occupancy of all or any part of the Premises by
another, without first obtaining Landlord's written consent, which consent shall
not be unreasonably withheld, conditioned or delayed. Notwithstanding any
permitted assignment or subletting, Tenant shall at all times remain directly,
primarily and fully responsible and liable for the payment of all sums payable
under this Lease and for compliance with all of its other obligations as tenant
under this Lease. Landlord's acceptance of Base Rent, Additional Rent or any
other sum from any assignee, sublessee, transferee, mortgagee or encumbrance
holder shall not be deemed to be Landlord's approval of any such conveyance.
Upon the occurrence of an Event of Default, if the Premises or any part of the
Premises are then subject to an assignment or subletting, Landlord may, at its
option, collect directly from such assignee or subtenant all rents becoming due
to Tenant under such assignment or sublease and apply such rents against any
sums due to Landlord from Tenant under this Lease. No such collection shall be
construed to constitute a novation or release of Tenant from the further
performance of Tenant's obligations under this Lease. Landlord's right of direct
collection shall be in addition to and not in limitation of any other rights and
remedies provided for in this Lease or at law. Tenant makes an absolute
assignment to Landlord of such assignments and subleases and any rent, lease
security deposits and other sums payable under such assignments and subleases as
collateral to secure the performance of the obligations of Tenant under this
Lease.

         4.16.2   In the event Tenant desires to assign this Lease or to sublet
all or any portion of the Premises, Tenant shall give written notice of such
desire to Landlord setting forth the name of the proposed subtenant or assignee,
the proposed term, the nature of the proposed subtenant's or assignee's business
to be conducted on the Premises, the rental rate, and any other particulars of
the proposed subletting or assignment that Landlord may reasonably request.
Without limiting the preceding sentence, Tenant shall also provide Landlord
with: (a) such financial information as Landlord may reasonably request
concerning the proposed subtenant or assignee, including recent financial
statements certified as accurate and complete by the president, managing partner
or other appropriate officer of the proposed subtenant or assignee and by a
certified public accountant in the case of a proposed assignment of this Lease
or the proposed subleasing of thirty-three thousand (33,000) or more rentable
square feet; (b) proof reasonably satisfactory to Landlord that the proposed
subtenant or assignee will immediately occupy and thereafter use the entire
Premises (or any sublet portion of the Premises) for the

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<PAGE>

remainder of the Lease Term (or for the entire term of the sublease, if shorter)
in compliance with the terms of this Lease; and (c) a copy of the proposed
sublease or assignment or letter of intent. Tenant shall pay to Landlord, upon
Landlord's demand therefor, Landlord's reasonable attorneys' fees incurred in
the review of such documentation and in documenting Landlord's consent. Receipt
of such fees shall not obligate Landlord to approve the proposed assignment or
sublease.

         4.16.3   In determining whether to grant or withhold consent to a
proposed assignment or sublease, Landlord may consider, and weigh, any factor it
deems relevant, in its reasonable discretion.

         4.16.4   Within ten (10) Business Days after Landlord's receipt of all
required information to be supplied by Tenant pursuant to this paragraph,
Landlord shall notify Tenant of Landlord's approval, disapproval or conditional
approval of any proposed assignment or subletting or of Landlord's election to
recapture as described below. Landlord shall have no obligation to respond
unless and until all required information has been submitted. In the event
Landlord approves of any proposed assignment or subletting, Tenant and the
proposed assignee or sublessee shall execute and deliver to Landlord an
assignment (or subletting) and assumption agreement in form and content
reasonably satisfactory to Landlord.

         4.16.5   Any transfer, assignment or hypothecation of any of the stock
or interest in Tenant, or the assets of Tenant, or any other transaction,
merger, reorganization or event, however constituted which (a) results in fifty
percent (50%) or more of such stock, interest or assets going into different
ownership, or (b) is a subterfuge denying Landlord the benefits of this
paragraph, shall be deemed to be an assignment within the meaning and provisions
of this paragraph and shall be subject to the provisions of this paragraph.
Notwithstanding the foregoing, no transfer of more than fifty percent (50%) of
any stock or interest in Tenant shall be deemed to be an assignment within the
meaning and provisions of this subparagraph 4.16.5 as long as Tenant remains a
corporation the outstanding voting stock of which is publicly traded and listed
on a "national securities exchange" (as defined in the Securities and Exchange
Act of 1934).

         4.16.6   If Landlord consents to any assignment or sublease and Tenant
receives rent or any other consideration, either initially or over the term of
the assignment or sublease, in excess of the Base Rent and Additional Rent (or,
in the case of a sublease of a portion of the Premises, in excess of the Base
Rent paid by Tenant on a square footage basis under this Lease), Tenant shall
pay to Landlord fifty percent (50%) of such excess, after deduction of
reasonable expenses in making such assignment or sublease including, without
limitation, reasonable legal fees, reasonable costs of preparing the applicable
premises, and reasonable brokerage fees.

         4.16.7   Landlord shall have the right to recapture the Premises or the
applicable portion thereof (a "Recapture") by giving written notice of such
Recapture to Tenant within fifteen (15) Business Days after receipt of Tenant's
written request for Landlord's consent to such proposed assignment or
subletting. Tenant shall have no right to retract its request for Landlord's
consent to assign or sublease once such request has been made. Such Recapture
shall terminate this Lease as to the applicable space effective on the
prospective effective date of assignment or subletting, which shall be the last
day of a calendar month and shall not be earlier than forty-five (45) Business
Days after receipt of Tenant's request hereunder. If less than the entire
Premises are recaptured, this Lease shall remain in full force and effect with
respect to that remaining area not recaptured by Landlord and (x) the Base Rent
payable hereunder shall be reduced by the amount of Base Rent from time to time
payable hereunder for the recaptured portion of the Premises on a per rentable
square foot basis, and (y) Tenant's Pro Rata Share shall be adjusted as
appropriate. Tenant shall surrender that portion of the Premises recaptured by
Landlord in accordance with the terms and conditions of this Lease.
Notwithstanding the first sentence of this subparagraph, Landlord shall have no
right to Recapture the Premises or applicable portion thereof if: (a) Tenant's
proposed assignment or sublet is to an affiliate or wholly-owned subsidiary or
is to a reorganized entity under which no change in ownership has occurred, or
(b) Tenant's proposed assignment or sublet together with any previous
assignments and sublets encompass, in the aggregate, net rentable area equal to
or less than twenty percent (20%) of the total net rentable area of Premises.

         4.16.8   Notwithstanding any contrary provision in the previous
subparagraphs of this paragraph, provided that all amounts due under this Lease
have been paid in full and further provided that no Event of Default exits,
Landlord shall consent to and approve a proposed assignment of this Lease or
subletting of the Premises where the assignment or subletting is to an affiliate
or wholly-owned subsidiary or parent of the Tenant or a reorganized entity under
which no change of ownership has occurred, provided that (a)Tenant has delivered
to Landlord satisfactory evidence of the foregoing, (b) in the case of an
assignment,

                                       26

<PAGE>

the assignee assumes all of the liabilities and obligations of the Tenant under
this Lease in a writing in form and substance satisfactory to Landlord in its
reasonable discretion, (c) the proposed assignee or subtenant will have a
tangible net worth immediately following such transaction certified to Landlord
by an independent certified public accountant equal to or greater than the
tangible net worth of Tenant as of the date of this Lease, as determined in
accordance with generally accepted accounting principles, and (d) Tenant has
satisfied the requirements of Section 4.16.2. hereof. Tenant agrees that Tenant
shall remain liable for its obligations under this Lease, despite any such
transfer.

         4.16.9   Notwithstanding anything to the contrary in this Lease,
provided that all amounts due under this Lease have been paid in full and
further provided that no Event of Default exists, upon not less than fifteen
(15) Business Days advance written notice to Landlord and satisfaction of the
requirements of Paragraph 4.16.2 hereof, Landlord shall consent to and approve a
proposed assignment of this Lease to be made in conjunction or connection with
any merger, consolidation, corporate reorganization (other than pursuant to the
bankruptcy laws), or the sale of all or substantially all of the assets of
Tenant, provided that the resulting or surviving corporation or transferee (as
applicable) (a) assumes all of the liabilities and obligations of the Tenant
under this Lease in a writing in form and substance satisfactory to Landlord in
its reasonable discretion, and (b) will have a tangible net worth immediately
following such transaction certified to Landlord by an independent certified
public accountant equal to or greater than the tangible net worth of Tenant as
of the date of this Lease, as determined in accordance with generally accepted
accounting principles. Tenant agrees that Tenant shall remain liable for its
obligations under this Lease, despite any such transfer.

4.17     ASSIGNMENT BY LANDLORD. Landlord shall have the right to transfer and
assign, in whole or in part, its rights and obligations under this Lease and in
any and all of the Land or Building. If Landlord sells or transfers any or all
of the Building, including the Premises, Landlord and Landlord's Agents shall,
upon consummation of such sale or transfer, be released automatically from any
liability relating to obligations or covenants under this Lease to be performed
or observed after the date of such transfer, and in such event, Tenant agrees to
look solely to Landlord's successor-in-interest with respect to such liability;
provided that, as to the Lease Security Deposit and Prepaid Rent, Landlord shall
not be released from liability therefor unless Landlord has delivered (by direct
transfer or credit against the purchase price) the Lease Security Deposit or
Prepaid Rent to its successor-in-interest.

4.18     ESTOPPEL CERTIFICATES AND FINANCIAL STATEMENTS. Tenant shall, from time
to time, upon the written request of Landlord, execute, acknowledge and deliver
to Landlord or its designee a written statement stating: (a) the date this Lease
was executed and the date it expires; (b) the date Tenant entered into occupancy
of the Premises; (c) the amount of monthly Base Rent and Additional Rent and the
date to which such Base Rent and Additional Rent have been paid; and (d)
certifying that (1) this Lease is in full force and effect and has not been
assigned, modified, supplemented or amended in any way (or specifying the date
of the agreement so affecting this Lease); (2) to the best of Tenant's
knowledge, Landlord is not in breach of this Lease (or, if so, a description of
each such breach) and that no event, omission or condition has occurred which
would result, with the giving of notice or the passage of time, in a breach of
this Lease by Landlord; (3) this Lease represents the entire agreement between
the parties with respect to the Premises; (4) all required contributions by
Landlord to Tenant on account of Tenant Improvements have been received to date
and identifying any such remaining obligations of Landlord; (5) on the date of
execution, there exist no defenses or offsets which the Tenant has against the
enforcement of this Lease by the Landlord, or if Tenant has any such defenses or
offsets, an explanation of the same; (6) no Base Rent, Additional Rent or other
sums payable under this Lease have been paid in advance except for Base Rent and
Additional Rent for the then current month; (7) no security has been deposited
with Landlord (or, if so, the amount of such security); (8) it is intended that
any Tenant's statement may be relied upon by a prospective purchaser or
mortgagee of Landlord's interest or an assignee of any such mortgagee; and (9)
such other information as may be reasonably requested by Landlord. Landlord
shall not request such statements more than twice in any twelve (12) month
period, unless an Event of Default exists or such request is made in connection
with a sale, financing or refinancing contemplated by Landlord. If Tenant fails
to respond within five (5) Business Days of its receipt of a written request by
Landlord as provided in this paragraph, such shall be a breach of this Lease and
Tenant shall be deemed to have admitted the accuracy of any information supplied
by Landlord to a prospective purchaser, mortgagee or assignee. In addition,
Tenant shall, from time to time, upon the written request of Landlord, deliver
to or cause to be delivered to Landlord or its designee Tenant's most recent
(but in no event more than twelve (12) months old) financial statements
(including a

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<PAGE>

statement of operations and balance sheet and statement of cash flows) certified
as accurate by a certified public accountant and prepared in conformance with
generally accepted accounting principles for (i) Tenant, (ii) any entity which
owns a controlling interest in Tenant, (iii) any entity the controlling interest
of which is owned by Tenant, (iv) any successor entity to Tenant by merger or
operation of law, and (v) any guarantor of this Lease. Landlord shall not
request such financial statements more than once in any twelve (12) month
period, unless an Event of Default exists or such request is made in connection
with a sale, financing or refinancing contemplated by Landlord. As long as
Tenant remains a publicly traded company listed and in good standing on a
"national securities exchange" (as defined in the Securities and Exchange Act of
1934) and provided that Tenant has filed all financial information and reports
required to be filed by such exchange and/or applicable Governmental
Requirements, Tenant may satisfy this requirement by providing Landlord with
Tenant's most recent annual report filed with such exchange. Landlord will not
disclose any aspects of Tenant's financial statements that Tenant designates in
writing to Landlord as confidential except (1) to Landlord's actual and proposed
mortgagees, investment advisors, attorneys', accountants and other professional
consultants (2) any proposed purchasers, (3) in litigation between Landlord and
Tenant, and (4) if required by court order or other applicable Governmental
Requirements.

4.19     MODIFICATION FOR LENDER. If, in connection with obtaining construction,
interim or permanent financing for the Building or Land, Landlord's lender, if
any, shall request reasonable modifications to this Lease as a condition to such
financing, Tenant will not unreasonably withhold or delay its consent to such
modifications; provided that, such modifications do not increase the obligations
of Tenant under this Lease or materially adversely affect Tenant's rights under
this Lease.

4.20     HAZARDOUS SUBSTANCES.

         4.20.1   Neither Tenant, any of Tenant's Agents nor any other person
shall store, place, generate, manufacture, refine, handle, or locate on, in,
under or around the Land or Building any Hazardous Substance, except for
storage, handling and use of reasonable quantities and types of (i) cleaning
fluids and office supplies in the Premises in the ordinary course and the
prudent conduct of Tenant's business in the Premises, and (ii) diesel fuel for
the Generator, which fuel shall be stored by Tenant in a location approved by
Landlord, which approval shall not be unreasonably withheld, conditioned or
delayed. Tenant agrees that (a) the storage, handling and use of such permitted
Hazardous Substances must at all times conform to all Governmental Requirements
and to applicable fire, safety and insurance requirements; (b) the types and
quantities of permitted Hazardous Substances which are stored in the Premises
must be reasonable and appropriate to the nature and size of Tenant's operation
in the Premises and reasonable and appropriate for a first-class building of the
same or similar use and in the same market area as the Building; and (c) no
Hazardous Substance shall be spilled or disposed of on, in, under or around the
Land or Building or otherwise discharged from the Premises or any area adjacent
to the Land or Building. In no event will Tenant be permitted to store, handle
or use on, in, under or around the Premises any Hazardous Substance which will
increase the rate of fire or extended coverage insurance on the Land or
Building, unless: (1) such Hazardous Substance and the expected rate increase
have been specifically disclosed in writing to Landlord; (2) Tenant has agreed
in writing to pay any rate increase related to each such Hazardous Substance;
and (3) Landlord has approved in writing each such Hazardous Substance, which
approval shall be subject to Landlord's discretion.

         4.20.2   Tenant shall indemnify, defend and hold harmless Landlord and
Landlord's Agents from and against any and all Claims arising out of any breach
of any provision of this paragraph, which expenses shall also include laboratory
testing fees, personal injury claims, clean-up costs and environmental
consultants' fees. Tenant agrees that Landlord may be irreparably harmed by
Tenant's breach of this paragraph and that a specific performance action may
appropriately be brought by Landlord; provided that, Landlord's election to
bring or not bring any such specific performance action shall in no way limit,
waive, impair or hinder Landlord's other remedies against Tenant.

         4.20.3   As of the execution date of this Lease, Tenant represents and
warrants to Landlord that, except as otherwise disclosed by Tenant to Landlord,
Tenant has no intent to bring any Hazardous Substances on, in or under the
Premises except for the type and quantities authorized in the first paragraph of
the paragraph captioned "Hazardous Substances".

4.21     ACCESS LAWS.

         4.21.1   Tenant agrees to notify Landlord immediately if Tenant
receives notification or otherwise becomes aware of: (a) any condition or
situation on, in, under or around the Land or Building which may constitute a
violation of any Access Laws or (b) any threatened or actual lien, action or
notice that the

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<PAGE>

Land or Building is not in compliance with any Access Laws. If Tenant is
responsible for such condition, situation, lien, action or notice under this
paragraph, Tenant's notice to Landlord shall include a statement as to the
actions Tenant proposes to take in response to such condition, situation, lien,
action or notice. Landlord agrees to notify Tenant immediately if Landlord
receives notification or otherwise becomes aware of: (a) any condition or
situation on, in, under or around the common areas of the Land or Building which
may constitute a violation of any Access Laws or (b) any threatened or actual
lien, action or notice that any common areas of the Land or Building is not in
compliance with any Access Laws. If Landlord is responsible for such condition,
situation, lien, action or notice under this paragraph, Landlord's notice to
Tenant shall include a statement as to the actions Landlord proposes to take in
response to such condition, situation, lien, action or notice.

         4.21.2   Tenant shall not alter or permit any assignee or subtenant or
any other person to alter the Premises in any manner which would violate any
Access Laws or increase Landlord's responsibilities for compliance with Access
Laws, without the prior approval of the Landlord, which approval shall not be
unreasonably withheld, conditioned or delayed. In connection with any such
approval, Landlord may require a certificate of compliance with Access Laws from
an architect, engineer or other person acceptable to Landlord. Tenant agrees to
pay the reasonable fees incurred by such architect, engineer or other third
party in connection with the issuance of such certificate of compliance.
Landlord's consent to any proposed Tenant Alteration shall (a) not relieve
Tenant of its obligations or indemnities contained in this paragraph or this
Lease or (b) be construed as a warranty that such proposed alteration complies
with any Access Law.

         4.21.3   Tenant shall be solely responsible for all costs and expenses
relating to or incurred in connection with: (a) failure of the Premises to
comply with the Access Laws; and (b) bringing the Building and the common areas
of the Building into compliance with Access Laws, if and to the extent such
noncompliance arises out of or relates to: (1) Tenant's particular use of the
Premises, including the hiring of employees; (2) any Tenant Alterations to the
Premises; or (3) any Tenant Improvements constructed in the Premises at the
request of Tenant, regardless of whether such improvements are constructed prior
to or after the Commencement Date.

         4.21.4   Landlord agrees that any alterations, modifications, or
construction performed by Landlord in the common areas of the Building and the
Land shall comply with Access Laws and Landlord shall be responsible for all
costs and expenses relating to or incurred in connection with bringing the
common areas of the Building into compliance with Access Laws, unless such costs
and expenses are Tenant's responsibility as provided in the preceding
subparagraph. Any cost or expense paid or incurred by Landlord to bring the
Premises or common areas of the Building into compliance with Access Laws which
is not Tenant's responsibility under the preceding subparagraphs shall be
amortized over the useful economic life of the improvements (not to exceed ten
(10) years) with interest at the Prime Rate plus four (4) percentage points
compounded daily, and shall be an Operating Cost for purposes of this Lease.
Landlord warrants and represents that, as of the date of this Lease, the common
areas of the Building and the Land are in compliance with Access Laws.

         4.21.5   Each party agrees to indemnify, defend and hold harmless the
other party and its agents from and against any and all Claims arising out of or
relating to any failure of the indemnifying party or the indemnifying party's
agents to comply with the indemnifying party's obligations under this paragraph.

         4.21.6   The provisions of this paragraph shall supersede any other
provisions in this Lease regarding Access Laws, to the extent inconsistent with
the provisions of any other paragraphs.

4.22     QUIET ENJOYMENT. Landlord covenants that Tenant, upon paying Base Rent,
Additional Rent and all other sums payable under this Lease and performing all
covenants and conditions required of Tenant under this Lease shall and may
peacefully have, hold and enjoy the Premises without hindrance or molestation by
Landlord subject to the provisions of this Lease.

4.23     SIGNS.

         4.23.1   EXTERIOR SIGNS. (a) Notwithstanding anything to the contrary
in the Rules and Regulations and subject to Tenant obtaining any necessary
governmental approvals and the terms and conditions set forth herein, beginning
on the Construction Period Commencement Date and during such portion of the
Lease Term that Lightbridge, Inc. (or a permitted assignee of all of Tenant's
rights under this Lease) itself continues to use and occupy at least eighty
percent (80%) of the Premises, Tenant shall have the exclusive right to install
and maintain two (2) exterior signs (identifying Lightbridge, Inc. or the
permitted assignee of all of Tenant's rights under this Lease) on the Building
in the locations and of the sizes, colors, designs, and specifications set forth
in Exhibit G attached to this Lease (collectively, the "Exterior Signs"),
provided that

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<PAGE>

the installation and maintenance of such Exterior Signs complies with all
Governmental Requirements and all matters of record. The installation of such
Exterior Signs shall constitute a Tenant Alteration and, as such, shall be
subject to all terms hereof applicable to Tenant Alterations including, without
limitation, the paragraph entitled "Tenant's Work Performance." . If Exhibit G
does not describe the exact sizes, colors, designs, and specifications of such
Exterior Signs, then the same shall be subject to Landlord's prior written
approval, which approval shall not be unreasonably withheld. If, at any time
during the Lease Term, Lightbridge, Inc. (or a permitted assignee of all of
Tenant's rights under this Lease) ceases to itself use and occupy at least
eighty percent (80%) of the Premises and/or an Event of Default occurs, Landlord
in its sole discretion may terminate Tenant's right to maintain the Exterior
Signs and may require Tenant to permanently remove the Exterior Signs.

         (b) Prior to installation of the Exterior Signs, Tenant shall obtain
any and all necessary permits and approvals required by applicable Governmental
Requirements. At Tenant's request and at Tenant's sole cost and expense,
Landlord shall cooperate with and assist Tenant in any way Tenant from time to
time may reasonably request in connection with its efforts to obtain such
permits and approvals, and Tenant shall reimburse Landlord on demand for any
reasonable expenses incurred by Landlord in connection therewith. Thereafter,
Tenant shall at all times maintain all necessary permits and approvals required
by the applicable Governmental Requirements in effect from time to time. Any and
all costs in connection with the permitting, fabrication, installation and
maintenance of the Exterior Signs shall be borne by Tenant. Tenant agrees to
maintain the Exterior Signs in good condition at all times. Upon vacation of the
Premises on the expiration or earlier termination of this Lease or at such
earlier time as Tenant is no longer permitted to maintain the Exterior Signs,
Tenant shall be responsible, at its sole cost, for the removal of the Exterior
Signs and the repair, painting and/or replacement of the structure to which the
Exterior Signs are attached. If Tenant fails to perform such work or if Landlord
in its sole discretion elects to perform such work on Tenant's behalf, Landlord
may cause the same to be performed, and the reasonable cost thereof shall be
Additional Rent immediately due and payable upon rendition of a bill therefor.

         (c) Subject to Governmental Requirements and Landlord obtaining any
necessary governmental approvals, Landlord shall install and maintain a monument
sign at the entrance to the Park in a location and of size, colors, design, and
specifications determined by Landlord (the "Monument Sign"). Following execution
of this Lease, Landlord shall apply for and diligently pursue the necessary
governmental approvals for the Monument Sign. After receipt of all necessary
approvals, Landlord shall order the necessary materials and install the Monument
Sign using Landlord's reasonable diligent efforts. Landlord shall include
Lightbridge's name on the Monument Sign as long as (i) Lightbridge, Inc. (or a
permitted assignee of all of Tenant's rights under this Lease) itself continues
to use and occupy at least eighty percent (80%) of the Premises, and (ii) no
Event of Default has occurred. Tenant acknowledges and agrees that Landlord
shall be permitted to include the names of other tenants of the Park on the
Monument Sign, provided that no other tenant's panel on the Monument Sign shall
be larger or more prominent than that of Tenant as long as Tenant leases more
space in the Park than any other tenant. If, at any time during the Lease Term,
Lightbridge, Inc. (or a permitted assignee of all of Tenant's rights under this
Lease) ceases to itself use and occupy at least eighty percent (80%) of the
Premises and/or an Event of Default occurs, Landlord in its sole discretion may
permanently remove Tenant's name from the Monument Sign and Tenant shall have no
further rights with respect thereto.

         4.23.2   DIRECTORY AND INTERIOR SIGN. Tenant shall be permitted to have
its entity name listed on the main directory sign for the Building situated in
the main lobby of the Building. Tenant also shall be permitted to have one (1)
entryway sign bearing Tenant's name next to Tenant's entryway into the Premises.
Said sign shall be installed by Landlord at Tenant's expense and shall be of a
size, design and coloration, and in a location consistent with Landlord's
standard tenant entryway signage for the Building. Tenant shall reimburse
Landlord for the reasonable cost of such entryway sign within ten (10) days of
receipt of an invoice for same.

4.24     SUBORDINATION. Tenant subordinates this Lease and all rights of Tenant
under this Lease to any mortgage, deed of trust, ground lease, or similar
instrument which may from time to time be placed upon the Premises (and all
renewals, modifications, replacements and extensions of such encumbrances), and
each such mortgage, deed of trust, ground lease or lien or other instrument
shall be superior to and prior to this Lease, provided that, as long as Tenant
is not in default hereunder beyond any applicable cure period (a) Tenant's
occupancy of the Premises shall not be disturbed by the termination of any
ground lease or the foreclosure of any mortgage, and (b) the foreclosure of a
mortgage, the termination of any ground lease, the institution of any suit,
action, summary or other proceeding against the Landlord, or any

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successor to the Landlord, or any foreclosure brought by any mortgagee to
recover possession of the Premises, shall not, by operation of law or otherwise,
result in the cancellation or termination of the Lease and Tenant shall not be
disturbed in its possession of the Premises for any reason other than as
provided in this Lease. Notwithstanding the foregoing, the holder or beneficiary
of such mortgage, deed of trust, ground lease, or similar instrument shall have
the right to subordinate or cause to be subordinated any such mortgage, deed of
trust, ground lease, or similar instrument to this Lease or to execute a
non-disturbance agreement in favor of Tenant on the standard form utilized by
such lender or ground lessor. At the request of Landlord, the holder of such
mortgage or deed of trust or any ground lessor, Tenant shall execute,
acknowledge and deliver promptly in recordable form any instrument or
subordination agreement that Landlord or such holder may request, provided such
instrument or subordination agreement is consistent with the terms of this
Paragraph 4.24 (including clauses (a) and (b) of the first sentence of this
paragraph) and is otherwise commercially reasonable. Tenant further covenants
and agrees that, subject to the terms of this Paragraph 4.24 (including clauses
(a) and (b) of the first sentence of this paragraph), if the lender or ground
lessor acquires the Premises as a purchaser at any foreclosure sale or
otherwise, Tenant shall recognize and attorn to such party as landlord under
this Lease, and shall make all payments required hereunder to such new landlord
without deduction or set-off and, upon the request of such purchaser or other
successor, execute, deliver and acknowledge documents confirming such
attornment. Notwithstanding anything herein to the contrary, in no event shall
the lender or ground lessor which acquires the Premises as a purchaser at any
foreclosure sale or otherwise be (i) bound by any payment of Base Rent or
Additional Rent for more than one month in advance, (ii) bound by any amendment
or modification of this Lease made without the consent of the lender or ground
lessor, (iii) liable in any way to Tenant for any act or omission, neglect or
default on the part of the Landlord under this Lease (provided that the
foregoing shall not relieve any successor landlord from the Landlord's
maintenance and repair obligations under this Lease with respect to any
condition existing as of the date such successor landlord acquires title to the
Premises), (iv) obligated to perform any work or improvements to be done by
Landlord in the Premises, or (v) subject to any counterclaim or setoff which
theretofore accrued to Tenant against Landlord. Tenant waives the provisions of
any law or regulation, now or hereafter in effect, which may give or purport to
give Tenant any right to terminate or otherwise adversely affect this Lease or
the obligations of Tenant hereunder in the event that any such foreclosure or
termination or other proceeding is prosecuted or completed. In addition to and
not in limitation of the foregoing, contemporaneously with the execution of this
Lease by Landlord, Landlord shall deliver to Tenant a Subordination,
Non-Disturbance and Attornment Agreement consistent with the foregoing terms and
otherwise in a commercially reasonable form from each holder (if any) as of the
date of this Lease of a mortgage, ground lease, or deed of trust which has
priority over this Lease.

4.25     WORKERS COMPENSATION IMMUNITY. If and to the extent that Tenant is
obligated to indemnify, defend or hold harmless Landlord or Landlord's Agents
from any Claims arising from its use of the Premises or any act or failure to
act by Tenant or Tenant's Agents or otherwise, Tenant expressly waives, to and
in favor of Landlord and Landlord's Agents, its statutory workers compensation
act employers immunity relative to any injury to an employee or employees of
Tenant.

4.26     BROKERS. Each party to this Lease shall indemnify, defend and hold
harmless the other party from and against any and all Claims asserted against
such other party by any real estate broker, finder or intermediary relating to
any act of the indemnifying party in connection with this Lease.

4.27     LIMITATION ON RECOURSE. Landlord has executed this Lease by its trustee
signing solely in a representative capacity. Notwithstanding anything contained
in this Lease to the contrary, Tenant confirms that the covenants of Landlord
are made and intended, not as personal covenants of the trustee, or for the
purpose of binding the trustee personally, but solely in the exercise of the
representative powers conferred upon the trustee by its principal. Liability
with respect to the entry and performance of this Lease by or on behalf of
Landlord, however it may arise, shall be asserted and enforced only against
Landlord's estate and equity interest in the Building. Neither Landlord nor any
of Landlord's Agents shall have any personal liability in the event of any claim
against Landlord arising out of or in connection with this Lease, the
relationship of Landlord and Tenant or Tenant's use of the Premises. Further, in
no event whatsoever shall any Landlord's Agent have any liability or
responsibility whatsoever arising out of or in connection with this Lease, the
relationship of Landlord and Tenant or Tenant's use of the Premises. Any and all
personal liability, if any, beyond that which may be asserted under this
paragraph, is expressly waived and released by Tenant and by all persons
claiming by, through or under Tenant. This paragraph shall not limit any right
that Tenant might otherwise have to obtain injunctive relief against Landlord or
to

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take any other action which shall not involve the personal liability of Landlord
or any of Landlord's Agents to respond in monetary damages from Landlord's
assets other than the Landlord's interest in the Building, as aforesaid.

4.28     MECHANIC'S LIENS AND TENANT'S PERSONAL PROPERTY TAXES.

         4.28.1   Tenant shall have no authority, express or implied, to create
or place any lien or encumbrance of any kind or nature whatsoever upon, or in
any manner to bind, the interest of Landlord or Tenant in the Premises or to
charge the rentals payable under this Lease for any Claims in favor of any
person dealing with Tenant, including those who may furnish materials or perform
labor for any construction or repairs. Tenant shall immediately pay or cause to
be paid all sums legally due and payable by it on account of any labor performed
or materials furnished in connection with any work performed on the Premises on
which any lien is or can be validly and legally asserted against its leasehold
interest in the Premises and Tenant shall indemnify, defend and hold harmless
Landlord from any and all Claims arising out of any such asserted Claims. Tenant
agrees to give Landlord immediate written notice of any such Claim.

         4.28.2   Tenant shall be liable for all taxes levied or assessed
against personal property, furniture or fixtures placed by Tenant in the
Premises or anywhere else in the Building or on the Land including, without
limitation, the roof of the Building and the Tenant's Generator Area. Without
limiting the foregoing, Tenant shall be liable for all taxes levied or assessed
against the Rooftop Equipment and the Generator. If any such taxes for which
Tenant is liable are levied or assessed against Landlord or Landlord's property
and Landlord elects to pay them or if the assessed value of Landlord's property
is increased by inclusion of such personal property, furniture or fixtures and
Landlord elects to pay the taxes based on such increase, Tenant shall reimburse
Landlord for the sums so paid by Landlord, upon demand by Landlord.

4.29     ROOFTOP EQUIPMENT.

         4.29.1   Notwithstanding anything to the contrary contained in the
Rules and Regulations and subject to compliance with all applicable Governmental
Requirements and the terms and conditions of this Lease, and provided that such
installation and roof use shall not void any roof or other warranty applicable
to the Building, Tenant shall have the non-exclusive right to install and
maintain on the roof of the Building, at Tenant's sole cost and expense,
Telecommunication Facilities consisting of one (1) telecommunication antenna or
satellite dish and supplemental HVAC equipment (all of the foregoing
collectively, the "Rooftop Equipment") and associated wiring and cabling
("Tenant's Roof Rights") on the condition that such Rooftop Equipment is
specifically and exclusively for the use of Lightbridge, Inc. in the ordinary
course of its business. At Tenant's expense, Landlord shall make available
Tenant's Pro Rata Share of any conduit space in the vertical risers of the
Building which the Landlord from time to tome makes available to tenants of the
Building for purposes of running wiring and cabling in order to connect Tenant's
Rooftop Equipment to the Premises. Tenant's Rooftop Equipment shall in no event
occupy more than a two thousand (2,000) square foot area on the roof of the
Building. No additional rental shall be payable in respect of the installation
and use of such Rooftop Equipment and associated wiring and cabling. Landlord
has not made any representations or promises pertaining to the suitability of
the Building's rooftop for Tenant's use. Tenant, for the purpose of this
paragraph and its right to rooftop access hereunder, accepts the rooftop in its
"AS IS" condition.

         4.29.2   Prior to installation, Tenant will obtain any and all
necessary licenses, approvals, permits, etc., necessary for the installation,
maintenance and use of the Rooftop Equipment. No method of installation,
maintenance or removal of the Rooftop Equipment shall be permitted which
Landlord reasonably anticipates shall cause any warranty held by Landlord in
respect of the roof of the Building to be deemed void or otherwise adversely
affected thereby, nor adversely affect the Building structure or operating
systems.

         4.29.3   The installation of such Rooftop Equipment and associated
wiring and cabling shall be considered a Tenant Alteration for all purposes of
this Lease, and without limiting the generality of the foregoing, such
installation shall be subject to the terms and conditions of paragraphs 4.4 and
4.5 (Tenant Alterations and Tenant Work Performance, respectively). Prior to the
installation of such Rooftop Equipment and associated wiring and cabling, Tenant
shall provide Landlord with written plans and specifications showing the size of
the Rooftop Equipment, its location on the roof (including plan elevations to
indicate sightliness of location), operating parameters and radio frequencies
(as applicable), and means of installation (including whether any penetrations
of the roof shall be required for installation), all of which shall be subject
to the approval of Landlord and its consultant for such matters (currently Riser

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Management), which approval shall not be unreasonably withheld. Tenant shall
reimburse Landlord, within ten (10) Business Days after receipt of an invoice,
for all reasonable out-of-pocket costs and expenses incurred by Landlord related
to its review of Tenant's plans and specifications, including the fees and
expenses of Landlord's consultant (regardless of whether Landlord approves
Tenant's plans and specifications) and Tenant's installation. The installation
of the Rooftop Equipment shall be performed at Tenant's expense by Landlord or
by Tenant at Landlord's election and by contractors previously approved by
Landlord. In no event shall the Landlord's approval of Tenant's plans and
specifications be deemed a representation that Tenant's Rooftop Equipment or
plans and specifications comply with Governmental Requirements and/or the terms
of this Lease. Without limiting the foregoing, Landlord's approval of Tenant's
plans and specifications shall not be deemed a representation that use of
Tenant's Rooftop Equipment will not cause interference with other systems in the
Building. Landlord reserves the right to require Tenant to relocate its Rooftop
Equipment to another location on the roof of the Building upon thirty (30) days
advance written notice, provided that, in Landlord's reasonable opinion, such
move is necessary in order to preserve, protect or maintain, or to avoid damage
to, the roof or structural elements of the Building.

         4.29.4   Tenant, through its designated and approved employees and
contractors, shall be solely responsible for the maintenance and care of the
Rooftop Equipment and associated wiring and cabling and shall maintain the same
in a clean, sanitary and safe condition and in good repair and free of any
defects at all times during this Lease. Tenant, at its sole expense and risk,
shall ensure that a physical inspection of the Rooftop Equipment occurs at
intervals of no more than three (3) months and that this inspection include a
survey of structural integrity and a review and correction of any loose bolts,
fittings or other appurtenances. Tenant shall provide a written certification of
such inspections to Landlord not more than ten (10) days following each such
inspection. In the absence of such a certification, Landlord shall have the
right (but not the obligation) to conduct or arrange for such an inspection and
corrective action and to charge Tenant for such costs.

         4.29.5   Tenant covenants upon installation that the Rooftop Equipment
and the signals sent and received by any of such Rooftop Equipment will not
interfere with signals of other tenants' communications equipment located on the
roof of (or in) the Building or in the office park in which the Building is
located or with other equipment associated with the operation of the Building or
any other building located in such office park. Upon receipt of notice from
Landlord, Tenant shall eliminate any such interference.

         4.29.6   Tenant's Roof Rights shall be exercised in such manner as: (1)
will not create any hazardous condition or interfere with or impair the
operation of the heating, ventilation, air conditioning, plumbing, electrical,
fire protection, life safety, public utilities or other systems or facilities of
the Building, (2) will not directly or indirectly interfere with, delay,
restrict or impose any expense, work or obligation upon Landlord in the use or
operation of the Building, and (3) shall not in any way conflict with any
Governmental Requirement now in force or which may hereafter be enacted. The
Tenant will, at its sole cost and expense, promptly comply or ensure that the
Building complies with all Governmental Requirements or requirements of any
board of fire insurance underwriters or other similar bodies now or hereafter
constituted relating to or affecting Tenant's roof use. If the rate of any
insurance carried by Landlord is increased as a result of Tenant's roof use,
then Tenant from time to time will pay to Landlord within ten (10) Business Days
after demand by Landlord a sum equal to such increased cost.

         4.29.7   Without limiting any other indemnification contained herein,
Tenant shall indemnify and hold Landlord harmless from and against any and all
Claims arising out of (a) any violations of Governmental Requirements relating
to Tenant's Rooftop Equipment and related facilities, and (b) the installation,
maintenance and/or use of such Rooftop Equipment and related facilities.

         4.29.8   Tenant's Roof Rights shall not be transferable to any other
party and shall be used solely in the ordinary course of Tenant's business
operations. Without limiting the foregoing, Tenant shall have no right to
sublease, sublicense or permit any other party to use Tenant's Roof Rights or
any of Tenant's Rooftop Equipment, except in connection with a sublease or
assignment which has been approved by Landlord in accordance with the terms and
conditions of Paragraph 4.16 hereof.

         4.29.9   Unless Landlord agrees in writing to permit Tenant to leave
the Rooftop Equipment in place, upon the expiration or earlier termination of
the Lease Term, Tenant shall remove its Rooftop Equipment and all associated
wiring and cabling connecting the Rooftop Equipment to Tenant's Premises and
repair any and all damage caused to the roof or any other part of the Building
by the installation or removal of said Rooftop Equipment. If Tenant fails to
remove any such Rooftop Equipment and all associated wiring and cabling
connecting the Rooftop Equipment to Tenant's Premises prior to the

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<PAGE>

expiration or earlier termination of the Lease, Landlord may do so and Tenant
shall pay the entire cost thereof to Landlord within ten (10) Business Days
after Tenant's receipt of Landlord's written demand therefor, which obligation
shall survive expiration or earlier termination of the Lease.

         4.29.10  Upon reasonable notice, the Landlord shall permit Tenant to
access the roof of the Building at reasonable times for purposes of Tenant's
exercise of its rights under this Section 4.29.

4.30     GENERATOR.

         4.30.1   Notwithstanding anything to the contrary contained in the
Rules and Regulations and subject to compliance with all applicable Governmental
Requirements and the terms and conditions of this Lease, and provided that such
installation shall not void any warranty applicable to the Building, Tenant
shall have the non-exclusive right to install and maintain in the Tenant's
Generator Area (as defined below), at Tenant's sole cost and expense, one (1)
electrical generator (the "Generator") and associated wiring and cabling
("Tenant's Generator Rights") on the condition that such Generator is
specifically and exclusively for the use of Lightbridge, Inc., and any assignee
or sublessee permitted hereunder, in the ordinary course of its business. At
Tenant's expense, Landlord shall make available Tenant's Pro Rata Share of any
conduit space in the vertical risers of the Building which the Landlord from
time to time makes available to tenants of the Building for purposes of running
wiring and cabling in order to connect Tenant's Generator to the Premises. As
used herein, "Tenant's Generator Area" means and refers to that portion of the
loading dock area of the Building shown as "Tenant's Generator Area" on the plan
attached hereto as Exhibit J. No additional rental shall be payable in respect
of the installation and use of the Generator and associated wiring and cabling.
Landlord has not made any representations or promises pertaining to the
suitability of the Tenant's Generator Area for Tenant's use. Tenant, for the
purpose of this paragraph and its right to access the Tenant's Generator Area
hereunder, accepts the Tenant's Generator Area in its "AS IS" condition.

         4.30.2   Prior to installation, Tenant will obtain any and all
necessary licenses, approvals, permits, etc., necessary for the installation,
maintenance and use of the Generator. No method of installation, maintenance or
removal of the Generator shall be permitted which Landlord reasonably
anticipates shall cause any warranty held by Landlord in respect of the Building
to be deemed void or otherwise adversely affected thereby, nor adversely affect
the Building structure or operating systems.

         4.30.3   The installation of such Generator and associated wiring and
cabling shall be considered a Tenant Alteration for all purposes of this Lease,
and without limiting the generality of the foregoing, such installation shall be
subject to the terms and conditions of paragraphs 4.4 and 4.5 (Tenant
Alterations and Tenant Work Performance, respectively). Prior to the
installation of such Generator and associated wiring and cabling, Tenant shall
provide Landlord with written plans and specifications showing the size of the
Generator, its location in Tenant's Generator Area (including plan elevations to
indicate sightliness of location), operating specifications, and means of
installation, all of which shall be subject to the approval of Landlord and its
consultant for such matters, which approval shall not be unreasonably withheld.
Without limiting the foregoing, the Generator shall be screened in a manner
reasonably satisfactory to the Landlord. Tenant shall reimburse Landlord, within
ten (10) Business Days after receipt of an invoice, for all reasonable
out-of-pocket costs and expenses incurred by Landlord related to its review of
Tenant's plans and specifications, including the fees and expenses of Landlord's
consultant (regardless of whether Landlord approves Tenant's plans and
specifications) and Tenant's installation. The installation of the Generator
shall be performed at Tenant's expense by Landlord or by Tenant at Landlord's
election and by contractors previously approved by Landlord. In no event shall
the Landlord's approval of Tenant's plans and specifications be deemed a
representation that Tenant's Generator or plans and specifications comply with
Governmental Requirements and/or the terms of this Lease. Without limiting the
foregoing, Landlord's approval of Tenant's plans and specifications shall not be
deemed a representation that use of Tenant's Generator will not cause
interference with other systems in the Building. Landlord reserves the right to
require Tenant to relocate its Generator to another location upon thirty (30)
days advance written notice, provided that, in Landlord's reasonable opinion,
such move is necessary in order to protect the safety and well being of persons
and/or to preserve, protect or maintain, or to avoid damage to, the Building or
other property.

         4.30.4   Tenant, through its designated and approved employees and
contractors, shall be solely responsible for the maintenance and care of the
Generator and associated wiring and cabling and shall maintain the same in a
clean, sanitary and safe condition and in good repair and free of any defects at
all times during this Lease. Tenant, at its sole expense and risk, shall ensure
that a physical inspection of the Generator occurs at intervals of no more than
one (1) month and that this inspection include a survey

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of structural integrity and a review and correction of any loose bolts, fittings
or other appurtenances. Tenant shall provide a written certification of such
inspections to Landlord not more than ten (10) days following each such
inspection. In the absence of such a certification, Landlord shall have the
right (but not the obligation) to conduct or arrange for such an inspection and
corrective action and to charge Tenant for such costs.

         4.30.5   Tenant covenants upon installation that the Generator will not
interfere with other equipment associated with the operation of the Building or
any other building of the office park in which the Building is located. Upon
receipt of notice from Landlord, Tenant shall eliminate any such interference.

         4.30.6   Tenant's Generator Rights shall be exercised in such manner
as: (1) will not create any hazardous condition or interfere with or impair the
operation of the heating, ventilation, air conditioning, plumbing, electrical,
fire protection, life safety, public utilities or other systems or facilities of
the Building, (2) will not directly or indirectly interfere with, delay,
restrict or impose any expense, work or obligation upon Landlord in the use or
operation of the Building, and (3) shall not in any way conflict with any
Governmental Requirement now in force or which may hereafter be enacted. The
Tenant will, at its sole cost and expense, promptly comply or ensure that the
Building complies with all Governmental Requirements or requirements of any
board of fire insurance underwriters or other similar bodies now or hereafter
constituted relating to or affecting Tenant's installation, maintenance, use,
and removal of the Generator. If the rate of any insurance carried by Landlord
is increased as a result of Tenant's installation, maintenance, use, and removal
of the Generator, then Tenant from time to time will pay to Landlord within ten
(10) Business Days after demand by Landlord a sum equal to such increased cost.

         4.30.7   Without limiting any other indemnification contained herein,
Tenant shall indemnify and hold Landlord harmless from and against any and all
Claims arising out of (a) any violations of Governmental Requirements relating
to Tenant's Generator and related facilities, and (b) the installation,
maintenance use and/or removal of such Generator and related facilities.

         4.30.8   Tenant's Generator Rights shall not be transferable to any
other party and shall be used solely in the ordinary course of Tenant's business
operations. Without limiting the foregoing, Tenant shall have no right to
sublease, sublicense or permit any other party to use Tenant's Generator Rights
or Tenant's Generator, except in connection with a sublease or assignment which
has been approved by Landlord in accordance with the terms and conditions of
Paragraph 4.16 hereof.

         4.30.9   Unless Landlord agrees in writing to permit Tenant to leave
the Generator in place, upon the expiration or earlier termination of the Lease
Term, Tenant shall remove its Generator and all associated wiring and cabling
connecting the Generator to Tenant's Premises and repair any and all damage
caused to the Tenant's Generator Area or any other part of the Building and/or
Land by the installation or removal of said Generator. If Tenant fails to remove
any such Generator and all associated wiring and cabling connecting the
Generator to Tenant's Premises prior to the expiration or earlier termination of
the Lease, Landlord may do so and Tenant shall pay the entire cost thereof to
Landlord within ten (10) Business Days after Tenant's receipt of Landlord's
written demand therefor, which obligation shall survive expiration or earlier
termination of the Lease.

         4.30.10  Upon reasonable notice, the Landlord shall permit Tenant to
access the Tenant's Generator Area of the Building at reasonable times for
purposes of Tenant's exercise of its rights under this Section 4.30.

4.31     NO OFFSET; INDEPENDENT COVENANTS; WAIVER. Rent shall be paid without
notice or demand, and without setoff, counterclaim, defense, abatement,
suspension, deferment, reduction or deduction, except as expressly provided
herein. Tenant waives all rights (i) to any abatement, suspension, deferment,
reduction or deduction of or from Rent, except to the extent otherwise expressly
set forth herein, and (ii) to quit, terminate or surrender this Lease or the
Premises or any part thereof, except as expressly provided herein. TENANT HEREBY
ACKNOWLEDGES AND AGREES THAT THE OBLIGATIONS OF TENANT HEREUNDER SHALL BE
SEPARATE AND INDEPENDENT COVENANTS AND AGREEMENTS, THAT RENT SHALL CONTINUE TO
BE PAYABLE IN ALL EVENTS AND THAT THE OBLIGATIONS OF TENANT HEREUNDER SHALL
CONTINUE UNAFFECTED, UNLESS THE REQUIREMENT TO PAY OR PERFORM THE SAME SHALL
HAVE BEEN TERMINATED PURSUANT TO AN EXPRESS PROVISION OF THIS LEASE. LANDLORD
AND TENANT EACH ACKNOWLEDGES AND AGREES THAT THE INDEPENDENT NATURE OF THE
OBLIGATIONS OF TENANT HEREUNDER REPRESENTS FAIR, REASONABLE, AND ACCEPTED
COMMERCIAL PRACTICE WITH RESPECT TO THE TYPE OF PROPERTY SUBJECT TO THIS LEASE,
AND THAT THIS AGREEMENT IS THE PRODUCT OF FREE AND INFORMED

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NEGOTIATION DURING WHICH BOTH LANDLORD AND TENANT WERE REPRESENTED BY COUNSEL
SKILLED IN NEGOTIATING AND DRAFTING COMMERCIAL LEASES IN MASSACHUSETTS, AND THAT
THE ACKNOWLEDGEMENTS AND AGREEMENTS CONTAINED HEREIN ARE MADE WITH FULL
KNOWLEDGE OF THE HOLDING IN WESSON V. LEONE ENTERPRISES, INC., 437 MASS. 708
(2002). SUCH WAIVER AND ACKNOWLEDGEMENTS BY TENANT ARE A MATERIAL INDUCEMENT TO
LANDLORD ENTERING INTO THIS LEASE.

                         SECTION 5: DEFAULT AND REMEDIES

5.1      EVENTS OF DEFAULT.

         5.1.1    The occurrence of any one or more of the following events
shall constitute a material default and breach of this Lease by Tenant ("Event
of Default"):

                  (a)      abandonment of all or any portion of the Premises
and/or vacation of more than fifty percent (50%) of the Premises (excluding any
assignments or subleases which have been approved by Landlord in accordance with
the terms and conditions of Paragraph 4.16 hereof);

                  (b)      failure by Tenant to make any payment of Base Rent,
Additional Rent or any other sum payable by Tenant under this Lease within three
(3) Business Days after written notice from Landlord that such payment was not
paid when due, provided, however, Landlord need not give any such notice more
than twice in any twelve (12) month period, and any further failure by Tenant
within any such twelve (12)month period to make any payment of Base Rent,
Additional Rent or any other sum payable by Tenant under this Lease within three
(3) Business Days after its due date shall constitute an immediate Event of
Default without any notice from Landlord;

                  (c)      failure by Tenant to observe or perform any covenant
or condition of this Lease, other than the making of payments, where such
failure shall continue for a period of fifteen (15) Business Days after written
notice from Landlord, provided, however, if cure is not reasonably capable of
being completed within such time period, Tenant shall have such additional
reasonable time (not to exceed an additional sixty (60) calendar days) as is
required to cure such default as long as Tenant promptly commences such cure
within said fifteen (15) Business Day period and thereafter diligently pursues
such cure to completion;

                  (d)      the failure of Tenant to surrender possession of the
Premises at the expiration or earlier termination of this Lease in the condition
required by this Lease;

                  (e)      (1) the making by Tenant of any general assignment or
general arrangement for the benefit of creditors; (2) the filing by or against
Tenant of a petition in bankruptcy, including reorganization or arrangement,
unless, in the case of a petition filed against Tenant, unless the same is
dismissed within twenty (20) Business Days; (3) the appointment of a trustee or
receiver to take possession of substantially all of Tenant's assets located in
the Premises or of Tenant's interest in this Lease; (4) any execution, levy,
attachment or other process of law against any property of Tenant or Tenant's
interest in this Lease, unless the same is dismissed within twenty (20) Business
Days; (5) adjudication that Tenant is bankrupt; or (6) the making by Tenant of a
transfer in fraud of creditors;

                  (f)      any information furnished by or on behalf of Tenant
to Landlord in connection with the entry of this Lease is determined to have
been materially false, misleading or incomplete when made; or

                  (g)      the failure of the Tenant to deliver the Letter of
Credit within the time period specified in the paragraph captioned "Lease
Security".

         5.1.2    Tenant shall notify Landlord promptly of any Event of Default
or any facts, conditions or events which, with the giving of notice or passage
of time or both, would constitute an Event of Default.

         5.1.3    If a petition in bankruptcy is filed by or against Tenant, and
if this Lease is treated as an "unexpired lease" under applicable bankruptcy law
in such proceeding, then Tenant agrees that Tenant shall not attempt nor cause
any trustee to attempt to extend the applicable time period within which this
Lease must be assumed or rejected.

5.2      REMEDIES. If any Event of Default occurs, Landlord may at any time
after such occurrence, with or without notice or demand except as stated in this
paragraph, and without limiting Landlord in the exercise of any right or remedy
at law which Landlord may have by reason of such Event of Default, exercise the
rights and remedies, either singularly or in combination, as are specified or
described in the subparagraphs of this paragraph.

                                       36

<PAGE>

         5.2.1    Landlord may terminate this Lease and all rights of Tenant
under this Lease either immediately or at some later date by giving Tenant
written notice that this Lease is terminated. If Landlord so terminates this
Lease, then Landlord may recover from Tenant the sum of:

                  (a)      the unpaid Base Rent, Additional Rent and all other
sums payable under this Lease which have been earned at the time of termination;

                  (b)      interest at the Default Rate on the unpaid Base Rent,
Additional Rent and all other sums payable under this Lease which have been
earned at the time of termination; plus

                  (c)      the amount by which the unpaid Base Rent, Additional
Rent and all other sums payable under this Lease which would have been earned
after termination until the time of award exceeds the amount of such rental
loss, if any, as Tenant affirmatively proves could have been reasonably avoided
and interest on such excess at the Default Rate; plus

                  (d)      the amount by which the aggregate of the unpaid Base
Rent, Additional Rent and all other sums payable under this Lease for the
balance of the Lease Term after the time of award exceeds the amount of such
rental loss, if any, as Tenant affirmatively proves could be reasonably avoided,
with such difference being discounted to present value at the Prime Rate at the
time of award; plus

                  (e)      any other amount necessary to compensate Landlord for
the detriment proximately caused by Tenant's failure to perform Tenant's
obligations under this Lease or which, in the ordinary course of things, would
be likely to result from such failure, including, leasing commissions, tenant
improvement costs, renovation costs and advertising costs; plus

                  (f)      all such other amounts in addition to or in lieu of
the foregoing as may be permitted from time to time by applicable law.

         5.2.2    Landlord shall also have the right, with or without
terminating this Lease, to re-enter the Premises and remove all persons and
property from the Premises. Landlord may cause property so removed from the
Premises to be stored in a public warehouse or elsewhere at the expense and for
the account of Tenant.

         5.2.3    [Intentionally Omitted]

         5.2.4    If Tenant abandons or surrenders the Premises without
Landlord's consent or vacates more than fifty percent (50%) of the Premises
(excluding any assignments or subleases which have been approved by Landlord in
accordance with the terms and conditions of Paragraph 4.16 hereof), or if
Landlord re-enters the Premises as provided in subparagraph 5.2.2 or takes
possession of the Premises pursuant to legal proceedings or through any notice
procedure provided by law, then, if Landlord does not elect to terminate this
Lease, Landlord may, from time to time, without terminating this Lease, either
(a) recover all Base Rent, Additional Rent and all other sums payable under this
Lease as they become due or (b) relet the Premises or any part of the Premises
on behalf of Tenant for such term or terms, at such rent or rents and pursuant
to such other provisions as Landlord, in its sole discretion, may deem
advisable, all with the right, at Tenant's cost, to make alterations and repairs
to the Premises and recover any deficiency from Tenant as set forth in
subparagraph 5.2.6.

         5.2.5    None of the following remedial actions, singly or in
combination, shall be construed as an election by Landlord to terminate this
Lease unless Landlord has in fact given Tenant written notice that this Lease is
terminated: (a) an act by Landlord to maintain or preserve the Premises; (b) any
efforts by Landlord to relet the Premises; (c) any repairs or alterations made
by Landlord to the Premises; (d) re-entry, repossession or reletting of the
Premises by Landlord pursuant to this paragraph; or (e) the appointment of a
receiver, upon the initiative of Landlord, to protect Landlord's interest under
this Lease. If Landlord takes any of the foregoing remedial action without
terminating this Lease, Landlord may nevertheless at any time after taking any
such remedial action terminate this Lease by written notice to Tenant.

         5.2.6    If Landlord relets the Premises, Landlord shall apply the
revenue from such reletting as follows: first, to the payment of any
indebtedness of Tenant to Landlord other than Base Rent, Additional Rent or any
other sums payable by Tenant under this Lease; second, to the payment of any
reasonable cost of reletting (including finders' fees and leasing commissions);
third, to the payment of the reasonable cost of any alterations, improvements,
maintenance and repairs to the Premises; and fourth, to the payment of Base
Rent, Additional Rent and other sums due and payable and unpaid under this
Lease. Landlord shall hold and apply the residue, if any, to payment of future
Base Rent, Additional Rent and other sums payable under this Lease as the same
become due, and shall deliver the eventual balance, if any, to Tenant. Should
revenue from letting during any month, after application pursuant to the
foregoing

                                       37

<PAGE>

provisions, be less than the sum of the Base Rent, Additional Rent and other
sums payable under this Lease and Landlord's expenditures for the Premises
during such month, Tenant shall be obligated to pay such deficiency to Landlord
as and when such deficiency arises.

         5.2.7    Pursuit of any of the foregoing remedies shall not preclude
pursuit of any of the other remedies provided in this Lease or by law (all such
remedies being cumulative), nor shall pursuit of any remedy provided in this
Lease constitute a forfeiture or waiver of any Base Rent, Additional Rent or
other sum payable under this Lease or of any damages accruing to Landlord by
reason of the violation of any of the covenants or conditions contained in this
Lease.

5.3      RIGHT TO PERFORM. If Tenant shall fail to pay any sum of money, other
than Base Rent or Additional Rent, required to be paid by it under this Lease or
shall fail to perform any other act on its part to be performed under this
Lease, and such failure shall continue for ten (10) Business Days after notice
of such failure by Landlord, or such shorter time if reasonable under the
circumstances, Landlord may, but shall not be obligated to, and without waiving
or releasing Tenant from any obligations of Tenant, make such payment or perform
such other act on Tenant's part to be made or performed as provided in this
Lease. Landlord shall have (in addition to any other right or remedy of
Landlord) the same rights and remedies in the event of the nonpayment of sums
due under this paragraph as in the case of default by Tenant in the payment of
Base Rent.

5.4      LANDLORD'S DEFAULT. Landlord shall not be in default under this Lease
with respect to its obligation to deliver possession of the Premises to Tenant
unless Landlord fails to so deliver the Premises within five (5) Business Days
after written notice is delivered by Tenant to Landlord and to the holder of any
mortgages or deeds of trust (collectively, "Lender") covering the Premises whose
name and address shall have theretofore been furnished to Tenant in writing. As
to all other obligations of Landlord hereunder, Landlord shall not be in default
under this Lease unless Landlord fails to perform obligations required of
Landlord within twenty (20) Business Days after written notice is delivered by
Tenant to Landlord and to any Lender, specifying the obligation which Landlord
has failed to perform; provided, however, that if the nature of Landlord's
obligation is such that more than twenty (20) Business Days are required for
performance, then Landlord shall not be in default if Landlord or Lender
commences performance within such twenty (20) Business Day period and thereafter
diligently prosecutes the same to completion. All obligations of Landlord
hereunder shall be construed as covenants, not conditions. In the event of any
default, breach or violation of Tenant's rights under this Lease by Landlord,
Tenant's exclusive remedy shall be either an action for specific performance or
an action for actual damages. Except as otherwise expressly provided herein,
Tenant hereby waives the benefit of any laws granting it the right to perform
Landlord's obligation, a lien upon the property of Landlord and/or upon Rent due
Landlord, or the right to terminate this Lease or withhold Rent on account of
any Landlord default. Notwithstanding the foregoing cure period, to the extent
the same is Landlord's obligation hereunder, Landlord shall be obligated to
commence to cure an emergency situation that creates an imminent danger of
bodily harm to any persons or an imminent danger of harm to property or material
interference with Tenant's business operations as soon as reasonably possible
following the date on which Landlord receives notice of such situation from
Tenant. In addition, following Tenant's notice to Landlord and the expiration of
the applicable cure period, except as otherwise provided herein, Tenant shall be
entitled to pursue any and all applicable remedies provided by Massachusetts law
in connection with such default by Landlord hereunder. In lieu of exercising its
rights and remedies under Massachusetts law, Tenant shall have the right to cure
a default by Landlord under the limited circumstances where each and all of the
following conditions exist (the "Self Help Conditions"): (1) all or
substantially all of the Premises have been rendered unusable by Tenant for the
Permitted Uses as a result of Landlord's default hereunder; (2) Landlord has
failed to cure the Landlord default within applicable notice and cure periods
and is not then diligently pursuing such cure; (3) prior to curing the default,
Tenant provides Landlord with at least fifteen (15) days written notice of the
fact that Tenant intends to cure the default on Landlord's behalf; (4) if there
is a Mortgage on the Building, Tenant has provided such Mortgagee with notice of
Landlord's default and has allowed such Mortgagee an opportunity (which in no
event shall be less than thirty (30) days after the expiration of Landlord's
cure period) to cure such default in accordance with the terms of any
subordination, non-disturbance and attornment agreement (or similar agreement)
between Tenant and such Mortgagee; and (5) the action required to cure the
default does not require Tenant to have access to the premises of any other
tenant or occupant of the Building. In attempting to cure any default by
Landlord, Tenant shall pursue the least expensive course of action that can
reasonably be expected to cure the default in question and shall perform only so
much work as is reasonably necessary to cure the

                                       38

<PAGE>

default. Tenant shall indemnify Landlord for any and all Claims in connection
with the performance of such work, including any claims by tenants or occupants
of the Building that are adversely affected by the performance of the work. Upon
completion of the curative work by Tenant and receipt of paid invoices, Landlord
shall reimburse Tenant for all reasonable expenses reasonably incurred by Tenant
in curing Landlord's default. If Landlord fails to repay Tenant for such costs
within fifteen (15) days after Landlord's receipt of the paid invoices, except
as otherwise provided herein, Tenant shall be entitled to pursue its remedies
under Massachusetts law for payment of such amount.

                       SECTION 6: MISCELLANEOUS PROVISIONS

6.1      NOTICES. Any notice, request, approval, consent or written
communication required or permitted to be delivered under this Lease shall be:
(a) in writing; (b) transmitted by personal delivery, express or courier
service, United States Postal Service in the manner described below, or
electronic means of transmitting written material; and (c) deemed to be
delivered on the earlier of the date received or four (4) Business Days after
having been deposited in the United States Postal Service, postage prepaid. Such
writings shall be addressed to Landlord or Tenant, as the case may be, at the
respective designated addresses set forth opposite their signatures, or at such
other address(es) as they may, after the execution date of this Lease, specify
by written notice delivered in accordance with this paragraph, with copies to
the persons at the addresses, if any, designated opposite each party's
signature. Those notices which contain a notice of breach or default or a demand
for performance may be sent by any of the methods described in clause (b) above,
but if transmitted by personal delivery or electronic means, shall also be sent
concurrently by certified or registered mail, return receipt requested.

6.2      ATTORNEY'S FEES AND EXPENSES. In the event either party requires the
services of an attorney in connection with enforcing the terms of this Lease, or
in the event suit is brought for the recovery of Base Rent, Additional Rent or
any other sums payable under this Lease or for the breach of any covenant or
condition of this Lease (including Landlord's delivery of the Premises to
Tenant), or for the restitution of the Premises to Landlord or the eviction of
Tenant during the Lease Term or after the expiration or earlier termination of
this Lease, the non-breaching party shall be entitled to a reasonable sum for
attorney's and paralegal's fees, expenses and court costs, including those
relating to any appeal.

6.3      NO ACCORD AND SATISFACTION. No payment by Tenant or receipt by Landlord
of an amount less than the Base Rent or Additional Rent or any other sum due and
payable under this Lease shall be deemed to be other than a payment on account
of the Base Rent, Additional Rent or other such sum, nor shall any endorsement
or statement on any check or any letter accompanying any check or payment be
deemed an accord and satisfaction, nor preclude Landlord's right to recover the
balance of any amount payable or Landlord's right to pursue any other remedy
provided in this Lease or at law.

6.4      SUCCESSORS; JOINT AND SEVERAL LIABILITY. Except as provided in the
paragraph captioned "Limitation on Recourse" and subject to the paragraph
captioned "Assignment and Subletting by Landlord", all of the covenants and
conditions contained in this Lease shall apply to and be binding upon Landlord
and Tenant and their respective heirs, executors, administrators, successors and
assigns. In the event that more than one person, partnership, company,
corporation or other entity is included in the term "Tenant", then each such
person, partnership, company, corporation or other entity shall be jointly and
severally liable for all obligations of Tenant under this Lease.

6.5      CHOICE OF LAW. This Lease shall be construed and governed by the laws
of the state in which the Land is located.

6.6      NO WAIVER OF REMEDIES. The waiver by Landlord of any covenant or
condition contained in this Lease shall not be deemed to be a waiver of any
subsequent breach of such covenant or condition nor shall any custom or practice
which may develop between the parties in the administration of this Lease be
construed to waive or lessen the rights of one party to insist on the strict
performance by the other party of all of the covenants and conditions of this
Lease. No act or thing done by Landlord or Landlord's Agents during the Lease
Term shall be deemed an acceptance or a surrender of the Premises, and no
agreement to accept a surrender of the Premises shall be valid unless made in
writing and signed by Landlord. The mention in this Lease of any particular
remedy shall not preclude a party from any other remedy it might have, either
under this Lease or at law, nor shall the waiver of or redress for any violation
of any covenant or condition in this Lease or in any of the rules or regulations
attached to this Lease or later adopted by Landlord, prevent a subsequent act,
which would have originally constituted a violation, from having all the force
and effect of an original violation. The receipt by Landlord and the payment by

                                       39

<PAGE>

Tenant of Base Rent, Additional Rent or any other sum payable under this Lease
with knowledge of a breach of any covenant or condition in this Lease shall not
be deemed a waiver of such breach. The failure of Landlord to enforce any of the
rules and regulations attached to this Lease or later adopted, against Tenant or
any other tenant in the Building, shall not be deemed a waiver. Any waiver by
either party must be in writing and signed by the waiving party to be effective.

6.7      OFFER TO LEASE. The submission of this Lease in a draft form to Tenant
or its broker or other agent does not constitute an offer to Tenant to lease the
Premises. This Lease shall have no force or effect until: (a) it is executed and
delivered by Tenant to Landlord; and (b) it is executed and delivered by
Landlord to Tenant.

6.8      FORCE MAJEURE. In the event that either party shall be delayed,
hindered in or prevented from the performance of any act or obligation required
under this Lease (other than the payment of money) by reason of acts of God,
strikes, lockouts, labor troubles or disputes, inability to procure or shortage
of materials or labor, failure of power or utilities, delay in transportation,
fire, vandalism, accident, flood, severe weather, other casualty, Governmental
Requirements (including mandated changes in the Plans and Specifications or the
Tenant Improvements resulting from changes in pertinent Governmental
Requirements or interpretations thereof), riot, insurrection, civil commotion,
sabotage, explosion, war, terrorism, natural or local emergency, acts or
omissions of others, including Tenant or Landlord (as applicable), or other
reasons of a similar or dissimilar nature not solely the fault of, or under the
exclusive control of, Landlord or Tenant (as applicable), then performance of
such act or obligation shall be excused for the period of the delay and the
period for the performance of any such act or obligation shall be extended for
the period equivalent to the period of such delay. Notwithstanding anything
herein to the contrary, except with respect to war, terrorism, civil
disturbances, fires, floods and other events which are commonly considered to be
"acts of God", the number of days of Force Majeure delay for each such event
shall be limited to one hundred fifty (150) days.

6.9      LANDLORD'S CONSENT. Unless otherwise provided in this Lease, whenever
Landlord's consent, approval or other action is required under the terms of this
Lease, such consent, approval or action shall be subject to Landlord's judgment
or discretion exercised in good faith and shall be delivered in writing.

6.10     SEVERABILITY; CAPTIONS. If any clause or provision of this Lease is
determined to be illegal, invalid, or unenforceable under present or future
laws, the remainder of this Lease shall not be affected by such determination,
and in lieu of each clause or provision that is determined to be illegal,
invalid or unenforceable, there be added as a part of this Lease a clause or
provision as similar in terms to such illegal, invalid or unenforceable clause
or provision as may be possible and be legal, valid and enforceable. Headings or
captions in this Lease are added as a matter of convenience only and in no way
define, limit or otherwise affect the construction or interpretation of this
Lease.

6.11     INTERPRETATION. Whenever a provision of this Lease uses the term (a)
"include" or "including", that term shall not be limiting but shall be construed
as illustrative, (b) "covenant", that term shall include any covenant,
agreement, term or provision, (c) "at law", that term shall mean as specified in
any applicable statute, ordinance or regulation having the force of law or as
determined at law or in equity, or both, and (d) "day", that uncapitalized word
shall mean a calendar day. This Lease shall be given a fair and reasonable
interpretation of the words contained in it without any weight being given to
whether a provision was drafted by one party or its counsel.

6.12     INCORPORATION OF PRIOR AGREEMENT; AMENDMENTS. This Lease contains all
of the agreements of the parties to this Lease with respect to any matter
covered or mentioned in this Lease, and no prior agreement or understanding
pertaining to any such matter shall be effective for any purpose. No provision
of this Lease may be amended or added to except by an agreement in writing
signed by the parties to this Lease or their respective successors in interest.

6.13     AUTHORITY. If Tenant is a partnership, company, corporation or other
entity, each individual executing this Lease on behalf of Tenant represents and
warrants to Landlord that he or she is duly authorized to so execute and deliver
this Lease and that all partnership, company, corporation or other entity
actions and consents required for execution of this Lease have been given,
granted or obtained. If Tenant is a partnership, company, corporation or other
business organization, it shall, within ten (10) Business Days after demand by
Landlord, deliver to Landlord satisfactory evidence of the due authorization of
this Lease and the authority of the person executing this Lease on its behalf.
The individual executing this Lease on behalf of Landlord' represents and
warrants to Tenant that he or she is duly authorized to so execute and deliver
this Lease and that all Trust or other entity actions and consents required for
execution of this Lease have been given, granted or obtained. Landlord, within
ten

                                       40

<PAGE>

(10) Business Days after demand by Tenant, shall deliver to Tenant satisfactory
evidence of the due authorization of this Lease and the authority of the person
executing this Lease on its behalf.

6.14     TIME OF ESSENCE. Time is of the essence with respect to the performance
of every covenant and condition of this Lease.

6.15     SURVIVAL OF OBLIGATIONS. Notwithstanding anything contained in this
Lease to the contrary or the expiration or earlier termination of this Lease,
any and all obligations of either party accruing prior to the expiration or
termination of this Lease shall survive the expiration or earlier termination of
this Lease, and either party shall promptly perform all such obligations whether
or not this Lease has expired or terminated. Such obligations shall include any
and all indemnity obligations set forth in this Lease.

6.16     CONSENT TO SERVICE. Tenant irrevocably consents to the service of
process of any action or proceeding at the address of the Premises. Nothing in
this paragraph shall affect the right to serve process in any other manner
permitted by law.

6.17     LANDLORD'S AUTHORIZED AGENTS. Notwithstanding anything contained in the
Lease to the contrary, including without limitation, the definition of
Landlord's Agents, only officers of Corporate Drive Corporation, the trustee of
Landlord, are authorized to amend, renew or terminate this Lease, or to
compromise any of Landlord's claims under this Lease or to bind Landlord in any
manner. Without limiting the effect of the pervious sentence, no property
manager or broker shall be considered an authorized agent of Landlord to amend,
renew or terminate this Lease, to compromise any of Landlord's claims under this
Lease or to bind Landlord in any manner.

6.18     WAIVER OF JURY TRIAL. Landlord and Tenant irrevocably waive the
respective rights to trial by jury in any action, proceeding or counterclaim
brought by either against the other (whether in contract or tort) on any matter
arising out of or relating in any way to this Lease, the relationship of
Landlord and Tenant or Tenant's use or occupancy of the Premises.

6.19     BUILDING DELIVERIES. Landlord acknowledges that the corridor from the
loading dock to the freight elevator is only thirty (30) inches wide at its
narrowest point. Therefore, Landlord agrees that Tenant shall be permitted
during the entire Lease Term to utilize the rear ground floor doors for access
to and from the freight elevator for purposes of receiving or removing from the
Premises items larger than thirty (30) inches in width. Notwithstanding the
foregoing, Tenant shall use the loading dock entrance and such corridor (rather
than the rear ground floor doors) for purposes of receiving or removing from the
Premises any items which will fit through such corridor as it presently exists
or as the same hereafter may be widened or reconfigured in Landlord's sole
discretion.

             <THE REMAINDER OF THIS PAGE INTENTIONALLY LEFT BLANK.>

                                       41

<PAGE>

         IN WITNESS WHEREOF, this Lease has been executed the day and year first
above set forth.

Designated Address for Landlord:                 LANDLORD:

Corporate Drive Corporation, as Trustee of       Corporate Drive Corporation,
Corporate Drive Nominee Realty Trust             as Trustee of Corporate Drive
c/o Kennedy Associates Real Estate Counsel, Inc. Nominee Realty Trust, a
Attention: Director of Asset Management          Massachusetts nominee trust

1215 Fourth Ave., 2400 Financial Center          By: ___________________________
Seattle, WA 98161                                    Patrick O. Mayberry
Facsimile: 206-682-4769                              President

with a copy to:                                  By: ___________________________
                                                     Robert B Edwards
                                                     Treasurer
Corporate Drive Corporation, as Trustee of
Corporate Drive Nominee Realty Trust
c/o Kennedy Associates Real Estate Counsel, Inc.
Attn: Vice President, Asset Management
7315 Wisconsin Avenue, Suite 350 West
Bethesda, MD 20814
Facsimile: 301-656-9339

with a copy to Manager at:

Trammell Crow Services, Inc.
25 Corporate Drive
Burlington, Massachusetts 01803
Facsimile: 781-272-6226

Designated Address for Tenant:                   TENANT:

Prior to Commencement Date:                      Lightbridge, Inc., a Delaware
                                                 corporation

Lightbridge, Inc.                                By: ___________________________
67 South Bedford Street                          Name: _________________________
Burlington, Massachusetts 01803                  Its: __________________________
Facsimile: ____________________________

From and after Commencement Date:

Lightbridge, Inc.
30 Corporate Drive
Burlington, Massachusetts 01803
Facsimile: _____________________________

                                       42

<PAGE>

                            LANDLORD ACKNOWLEDGEMENT

                           )
___________________        ) ss.
                           )

         On this _______ day of December 2003, before me, a Notary Public in and
for the ___________________________, personally appeared Patrick O Mayberry, the
President of Corporate Drive Corporation,. the Massachusetts corporation that
executed the within and foregoing instrument in its capacity as Trustee of
Corporate Drive Nominee Realty Trust, and acknowledged said instrument to be the
free and voluntary act and deed of said corporation in its capacity as Trustee
of Corporate Drive Nominee Realty Trust, for the uses and purposes therein
mentioned, and on oath stated that he was authorized to execute said instrument.

         IN WITNESS WHEREOF, I have hereunto set my hand and affixed my official
seal the day and year first above written.

                        ________________________________________________________
                        Name: __________________________________________________
                        NOTARY PUBLIC in and for the _____________________,
                        residing at ____________________. My appointment
                        expires: ______________________.

[NOTARIAL SEAL]

                                       43

<PAGE>

                      TENANT ACKNOWLEDGEMENT (CORPORATION)

_____________________________       )
                                    ) ss.
_____________________________       )

         On this _______ day of _______________, 2003, before me, a Notary
Public in and for the _________________________, personally appeared
_______________________________, the ________________________ of Lightbridge,
Inc., the Delaware corporation that executed the within and foregoing
instrument, and acknowledged said instrument to be the free and voluntary act
and deed of said corporation for the uses and purposes therein mentioned, and on
oath stated that s/he/they was/were authorized to execute said instrument.

         WITNESS my hand and official seal hereto affixed the day and year first
as above written.

                        ________________________________________________________
                        Name: __________________________________________________
                        NOTARY PUBLIC in and for the State of ______________ ,
                        residing at ____________________. My appointment
                        expires: ______________________.

[NOTARIAL SEAL]

                                       44

<PAGE>

                               EXHIBIT A to Lease

                              Intentionally Omitted

                                      Ex. A

                                        1

<PAGE>

                               EXHIBIT B to Lease

                    DRAWINGS SHOWING LOCATION OF THE PREMISES

                                      Ex. B

                                        1

<PAGE>

                               EXHIBIT C to Lease

           LISTING OF PLANS AND SPECIFICATIONS FOR TENANT IMPROVEMENTS

                                      Ex. C

                                        1

<PAGE>

                               EXHIBIT D to Lease

                              Intentionally Omitted

                                      Ex. D

                                        1

<PAGE>

                               EXHIBIT E to Lease

                              RULES AND REGULATIONS

         1.       No sign, placard, picture, advertisement, name or notice shall
be installed or displayed on any part of the outside or inside of the Building
or Land without the prior written consent of the Landlord. Landlord shall have
the right to remove, at Tenant's expense and without notice, any sign installed
or displayed in violation of this rule. All approved signs or lettering on doors
and walls shall be printed, painted, affixed or inscribed at the expense of
Tenant by a person chosen by Landlord.

         2.       If Landlord objects in writing to any curtains, blinds,
shades, screens or hanging plants or other similar objects attached to or used
in connection with any window or door of the Premises, Tenant shall immediately
discontinue such use. No awning shall be permitted on any part of the Premises.
Tenant shall not place anything against or near glass partitions or doors or
windows, which may appear unsightly from outside the Premises.

         3.       Tenant shall not obstruct any sidewalk, halls, passages,
exits, entrances, elevators, escalators, or stairways of the Building. The
halls, passages, exits, entrances, elevators, escalators and stairways are not
open to the general public. Landlord shall in all cases retain the right to
control and prevent access to such areas of all persons whose presence in the
judgment of Landlord would be prejudicial to the safety, character, reputation
and interest of the Land, Building and the Building's tenants; provided that,
nothing in this Lease contained shall be construed to prevent such access to
persons with whom any Tenant normally deals in the ordinary course of its
business, unless such persons are engaged in illegal activities. Tenant shall
not go upon the roof of the Building.

         4.       The directory of the Building will be provided exclusively for
the display of the name and location of tenants only, and Landlord reserves the
right to exclude any other names therefrom.

         5.       All cleaning and janitorial services for the Building and the
Premises shall be provided exclusively through Landlord, and except with the
written consent of Landlord, no person or persons other than those approved by
Landlord shall be employed by Tenant or permitted to enter the Building for the
purpose of cleaning the same. Cleaning and janitorial services shall be provided
five (5) days per week. Tenant shall not cause any unnecessary labor by
carelessness or indifference to the good order and cleanliness of the Premises.
Landlord shall not in any way be responsible to any Tenant for any loss of
property on the Premises, however occurring, or for any damage to any Tenant's
property by the janitor, any of Landlord's Agents or any other person.

         6.       Landlord will furnish Tenant, free of charge, two (2) keys to
each door lock in the Premises. Landlord may make a reasonable charge for any
additional keys. Tenant shall not make or have made additional keys, and Tenant
shall not alter any lock or install a new additional lock or bolt on any door of
its Premises. Tenant, upon the termination of its tenancy, shall deliver to
Landlord the keys of all doors which have been furnished to Tenant, and in the
event of loss of any keys so furnished, shall pay Landlord therefor.

         7.       [Intentionally Omitted]

         8.       If Tenant requires telegraphic, telephonic, computer circuits,
burglar alarm or similar services, it shall first obtain, and comply with,
Landlord's instructions for their installation, and shall pay the entire cost of
such installation(s).

         9.       Tenant shall not place a load upon any floor (or portion
thereof) of the Premises which exceeds the load per square foot which such floor
was designed to carry and which is allowed by Governmental Requirements. Heavy
objects shall, if considered necessary by Landlord, stand on such platforms as
determined by Landlord to be necessary to properly distribute the weight.
Business machines and mechanical equipment belonging to Tenant, which cause
noise or vibration that may be transmitted to the structure of the Building or
to any space in the Building or to any other tenant in the Building, shall be
placed and maintained by Tenant, at Tenant's expense, on vibration eliminators
or other devices sufficient to eliminate noise or vibration. The persons
employed to move such equipment in or out of the Building must be acceptable to
Landlord in Landlord's reasonable discretion. Except to the extent caused by
Landlord's gross negligence or intentional misconduct, Landlord will not be
responsible
                                      Ex. E

                                        1

<PAGE>

for loss of, or damage to, any such equipment or other property from any cause,
and all damage done to the Building by maintaining or moving such equipment or
other property shall be repaired at the expense of Tenant.

         10.      Tenant shall not use or keep in the Premises any kerosene,
gasoline or inflammable or combustible fluid or material other than those
limited quantities permitted by the Lease. Tenant shall not use or permit to be
used in the Premises any foul or noxious gas or substance, or permit or allow
the Premises to be occupied or used in a manner offensive or objectionable to
Landlord or other occupants of the Building by reason of noise, odors or
vibrations nor shall Tenant bring into or keep in or about the Premises any
birds or animals.

         11.      Tenant shall not use any method of heating or air-conditioning
other than that supplied by Landlord or approved by Landlord in accordance with
the terms of Paragraph 2.3 or 4.4 of the Lease (as applicable).

         12.      Tenant shall not waste any utility provided by Landlord and
agrees to cooperate fully with Landlord to assure the most effective operation
of the Building's heating and air-conditioning and to comply with any
governmental energy-saving rules, laws or regulations of which Tenant has actual
notice.

         13.      Landlord reserves the right, exercisable without notice and
without liability to Tenant, to change the name and street address of the
Building. Notwithstanding the foregoing, if such change is being made at the
discretion of the Landlord and is not required by the United States Postal
Service, the city or town in which the Land and/or Building is located or any
other third party having such right, Landlord shall not change the name and
street address of the Building more than once during the initial Lease Term
without the Tenant's consent, which consent shall not be unreasonably withheld,
conditioned or delayed. If such change is required by the United States Postal
Service, the city or town in which the Land and/or Building is located, or any
other third party, there shall be no limit on such changes.

         14.      Landlord reserves the right to exclude from the Building
between the hours of 6 p.m. and 7 a.m. the following day, or such other hours as
may reasonably be established from time to time by Landlord, and on Sundays and
legal holidays, any person unless that person is known to the person or employee
in charge of the Building and has a pass or is properly identified. Tenant shall
be responsible for all persons for whom it requests passes and shall be liable
to Landlord for all acts of such persons. Landlord shall not be liable for
damages for any error with regard to the admission to or exclusion from the
Building of any person. Landlord reserves the right to prevent access to the
Building in case of invasion, mob, riot, public excitement or other commotion by
closing the doors or by other appropriate action.

         15.      Tenant shall close and lock the doors of its Premises and
entirely shut off all water faucets or other water apparatus, and electricity,
gas or air outlets before Tenant and its employees leave the Premises. Tenant
shall be responsible for any damage or injuries sustained by other tenants or
occupants of the Building or by Landlord for noncompliance with this rule.

         16.      [Intentionally Omitted]

         17.      The toilet rooms, toilets, urinals, wash bowls and other
apparatus shall not be used for any purpose other than that for which they were
constructed and no foreign substance of any kind whatsoever shall be deposited
in them. The expenses of any breakage, stoppage or damage resulting from the
violation of this rule shall be borne by Tenant if it or its employees or
invitees shall have caused it.

         18.      Tenant shall not sell, or permit the sale at retail, of
newspapers, magazines, periodicals, theater tickets or any other goods or
merchandise to the general public in or on the Premises. Tenant shall not make
any room-to-room solicitation of business from other tenants in the Building.
Tenant shall not use the Premises for any business or activity other than that
specifically provided for in the Lease.

         19.      Tenant shall not install any radio or television antenna,
loudspeaker or other device on the roof or exterior walls of the Building.
Tenant shall not interfere with radio or television broadcasting or reception
from or in the Building or elsewhere.

         20.      Tenant shall not in any way deface the Premises. Landlord
reserves the right to direct

                                      Ex. E

                                        2

<PAGE>

electricians as to where and how telephone and telegraph wires are to be
introduced to the Premises. Tenant shall not cut or bore holes for wires. Tenant
shall not affix any floor covering to the floor of the Premises in any manner
except as approved by Landlord. Tenant shall repair any damage resulting from
noncompliance with this rule.

         21.      Tenant shall not install, maintain or operate upon the
Premises any vending machine without the written consent of Landlord, which
consent shall not be unreasonably withheld, conditioned or delayed.

         22.      Canvassing, soliciting and distribution of handbills or any
other written material, and peddling in the Building or Land are prohibited, and
Tenant shall cooperate to prevent the same.

         23.      Landlord reserves the right to exclude or expel from the
Building and Land any person who, in Landlord's judgment, is intoxicated, under
the influence of liquor or drugs or in violation of any of these Rules and
Regulations.

         24.      Tenant shall store all of its trash and garbage within the
Premises. Tenant shall not place in any trash box or receptacle any material,
which cannot be disposed of in the ordinary and customary manner of trash and
garbage disposal. All garbage and refuse disposal shall be made in accordance
with directions issued from time to time by Landlord.

         25.      The Premises shall not be used for lodging or any improper or
immoral or objectionable purpose. No cooking shall be done or permitted by
Tenant, except that use by Tenant of Underwriters' Laboratory approved microwave
ovens and equipment for brewing coffee, tea, hot chocolate and similar beverages
shall be permitted; provided that, such equipment and its use is in accordance
with all Governmental Requirements.

         26.      Tenant shall not use in the Premises or in the public halls of
the Building any hand truck except those equipped with rubber tires and side
guards or such other material-handling equipment as Landlord may approve. Tenant
shall not bring any other vehicles of any kind into the Building.

         27.      Without the prior written consent of Landlord, Tenant shall
not use the name of the Building in connection with or in promoting or
advertising the business of Tenant except as Tenant's address.

         28.      Tenant shall comply with all safety, fire protection and
evacuation procedures and regulations established by Landlord or any
governmental agency.

         29.      Tenant assumes any and all responsibility for protecting the
Premises from theft, robbery and pilferage, which includes keeping doors locked
and other means of entry to the Premises closed.

         30.      The requirements of Tenant will be attended to only upon
appropriate application to the Manager of the Building by an authorized
individual. Employees of Landlord are not required to perform any work or do
anything outside of their regular duties unless under special instructions from
Landlord, and no employee of Landlord is required to admit Tenant to any space
other than the Premises without specific instructions from Landlord.

         31.      Tenant shall not park its vehicles in any parking areas
designated by Landlord as areas for parking by visitors to the Building or Land.
Tenant shall not leave vehicles in the parking areas overnight nor park any
vehicles in the Building parking areas other than automobiles, motorcycles,
motor driven or nonmotor driven bicycles or four-wheeled trucks.

         32.      Landlord may waive any one or more of these Rules and
Regulations for the benefit of Tenant or any other tenant, but no such waiver by
Landlord shall be construed as a waiver of such Rules and Regulations in favor
of any other person, nor prevent Landlord from thereafter revoking such waiver
and enforcing any such Rules and Regulations against any or all of the tenants
of the Building.

         33.      These Rules and Regulations are in addition to, and shall not
be construed to in any way modify or amend, in whole or in part, the covenants
and conditions of any lease of premises in the Building. If any provision of
these Rules and Regulations conflicts with any provision of the Lease, the terms
of the Lease shall prevail.

         34.      Landlord reserves the right to make such other and reasonable
Rules and Regulations

                                      Ex. E

                                        3

<PAGE>

as, in its judgment, may from time to time be needed for safety and security,
the care and cleanliness of the Building and Land and the preservation of good
order in the Building. Tenant agrees to abide by all the Rules and Regulations
stated in this exhibit and any additional rules and regulations, which are so,
made by Landlord. Landlord agrees to use reasonable efforts to enforce the Rules
and Regulations against all tenants in the Building in a non-discriminatory
manner.

         35.      Tenant shall be responsible for the observance of all of the
foregoing rules by Tenant and Tenant's Agents.

                                      Ex. E

                                        4

<PAGE>

                               EXHIBIT F to Lease

                            LETTER OF CREDIT CRITERIA

1.       The letter of credit shall be clean, irrevocable and unconditional.

2.       The letter of credit shall be in the amount specified in the Lease
paragraph captioned "Security Provisions".

3.       The letter of credit must either (i) be issued by a national bank which
is a member of the New York Clearing House and which has a banking office
dedicated to the administration and payment of letters of credit in New York
City or Boston, Massachusetts or (ii) if issued by any bank which is not
described in clause (i), be confirmed by a bank described in clause (i). The
issuing bank must have been assigned by Standard & Poors Investor Services a
Bank Financial Strength Rating of BBB+, or better. If clause (ii) is applicable,
the confirming bank must be assigned by Standard & Poors Investor Services a
Bank Financial Strength Rating of BBB+, or better. The identity of the issuing
bank and of any confirming bank shall also be reasonably satisfactory to
Landlord.

4.       The letter of credit shall have an expiration date no earlier than the
first anniversary of the date of its issuance and shall provide for its
automatic renewal from year to year unless terminated by the issuing bank by
notice to Landlord given not less than forty-five (45) days prior to its
expiration date by registered or certified mail. The final expiration date of
the letter of credit and all renewals of it shall be no earlier than sixty (60)
days following the end of the Lease Term.

5.       The letter of credit shall be issued in favor of Landlord and shall be
effective immediately on its issuance.

6.       The letter of credit may be drawn at the New York City or Boston
banking office of either the issuer of the letter of credit described in clause
(a) of paragraph 3 or, if clause (b) of paragraph 3 is applicable, the
confirming bank described in clause (a) of such paragraph 3. It must allow for
draws to be made at sight on a draft drawn under the letter of credit which has
been approved as to form by Landlord. It must allow for one draw in the whole
amount or multiple partial draws. The Landlord shall not as a condition to any
draw be required to deliver any certificate, affidavit or other writing to the
issuer expressing the basis for the draw.

7.       The letter of credit shall be transferable.

8.       The letter of credit shall be governed by (a) the International Standby
Practices (SP 98 published by the International Chamber of Commerce and (b) the
United Nations Convention on Independent Guarantees and Standby Letters of
Credit. Alternatively, if approved by the lender and if required by either the
issuing bank or the confirming bank the Uniform Customs and Practices for
Documentary Credits published by the International Chamber of Commerce may be
substituted for the Practices referred to in clause (a) to the extent such
Customs and Practices are not inconsistent with the criteria in this Exhibit F.

9.       The letter of credit shall otherwise be in such form and shall be
subject to such requirements as Landlord may reasonably require.

                                      Ex. F

                                        1

<PAGE>

                               EXHIBIT G to Lease

                                EXTERIOR SIGNAGE

                                      Ex. G

                                        1

<PAGE>

                               EXHIBIT H to Lease

              FORM OF REQUISITION FOR TENANT IMPROVEMENT ALLOWANCE

                                      Ex. H

                                        1

<PAGE>

                               EXHIBIT I to Lease

                             CLEANING SPECIFICATIONS

                                BURLINGTON CENTRE

I.   General

     A.   All cleaning work will be performed between 6:00 pm and 10:00 pm,
          Monday through Friday, unless otherwise necessary for stripping,
          waxing etc.

     B.   Abnormal waste removal (e.g., computer installation paper, bulk
          packaging, wood or cardboard crates, refuse from cafeteria operation,
          etc.) shall be Tenant's responsibility.

II.  Daily Operations (5 times per week)

     A.   Tenant Areas

          1.   Empty and clean all waste receptacles; wash receptacles as
               necessary; remove waste material from the Premises.

          2.   Vacuum all rugs and carpeted areas.

          3.   Dust and mop all non-carpeted areas using a dust treated mop.

          4.   Wipe clean all brass and other bright work.

          5.   Turn out all lights and lock all doors upon completion of
               cleaning.

     B.   Lavatories

          1.   Sweep and wash floors with disinfectant.

          2.   Wash both sides of toilet seats with disinfectant.

          3.   Wash all mirrors, basins, bowls and urinals.

          4.   Spot clean toilet partitions.

          5.   Empty and disinfect sanitary product disposal receptacles.

          6.   Refill toilet tissue, towel, soap and sanitary product
               dispensers.

          7.   Remove waste paper and refuse.

          8.   Dust all powder rooms and fixtures, including shelves,
               dispensers, receptacles, bright work flushometers, piping and
               toilet seat hinges.

     C.   Public Areas

          1.   Wipe down entrance doors and clean glass (interior and exterior).

          2.   Vacuum elevator carpets and wipe down doors and walls.

          3.   Clean water coolers.

          4.   Wash all rubber mats.

III. Operations as Needed (but not less than weekly)

     A.   Tenant and Public Areas

          1.   Buff all resilient floor areas.

IV.  Weekly Operations

     A.   Tenant Areas, Lavatories and Public Areas

                                      Ex. I

                                        1

<PAGE>

          1.   Hand dust and wipe clean all horizontal surfaces with treated
               cloths to include furniture, office equipment, windowsills, door
               ledges, chair rails, baseboards, etc., within normal reach.

          2.   Remove finger marks from private entrance doors, light switches
               and doorways.

          3.   Sweep all stairways.

V.   Monthly Operations

     A.   Tenant and Public Areas

          1.   Thoroughly vacuum seat cushions on chairs and sofas, etc.

          2.   Vacuum and dust grillwork.

     B.   Lavatories

          1.   Wash down interior walls and toilet partitions.

          2.   Machine scrub lavatory floors.

VI.  Twice Per Year

     A.   Entire Building

          1.   Clean inside of all windows.

          2.   Clean outside of all windows.

VII. Yearly

     A.   Public Areas

          1.   Strip and wax all resilient tile floor areas.

                                      Ex. I

                                        2

<PAGE>

                               EXHIBIT J to Lease

                             Tenant's Generator Area

                                      Ex. J

                                        1

<PAGE>

                               EXHIBIT K to Lease

                Prior Rights of First Offer and/or First Refusal

-    Administaff Client Services, L.P has a prior right of first offer during
     its initial lease term which expires on February 29, 2008 to lease
     expansion space consisting of approximately four thousand two hundred
     sixteen (4,216) rentable square feet located adjacent to its current space
     on the first floor of the Building, all as shown on the floor plan attached
     hereto to this Exhibit K.

                                      Ex. K

                                        1