Document:

<PAGE>
                                                                   EXHIBIT 10.26

                                   UNSECURED
                                   ---------

                                     NOTE

$20,000,000.00                                    July 16, 1999

     ON DEMAND, for value received, the undersigned, ZEFER CORP, a Delaware
corporation (the "Company"), promises to pay to the order of HARRIS TRUST AND
SAVINGS BANK (the "Bank") at its offices at 111 West Monroe Street, Chicago,
Illinois, the principal sum of TWENTY MILLION and 00/100 Dollars
($20,000,000.00) or, if less, the amount outstanding under the letter agreement
referred to below together with interest (compound on the basis of a year of 360
days and actual days elapsed) on the principal amount from time to time
remaining unpaid hereto from the date hereof to the maturity thereof (whether by
demand or otherwise) at the rate per annum equal to the rate announced from time
to time by Harris Trust and Savings Bank as its prime commercial rate (with any
change in the Interest rate hereon by reason of a change in said prime
commercial rate to be and become effective as of and on the date of the relevant
change in said prime commercial rate) and after the maturity thereof until paid
at the rate per annum of two percent (2%) above the interest rate applicable to
this Note (determined as aforesaid) at such maturity. Interest shall be payable
on the last day of each month and upon demand.

     This Note evidences borrowings by the Company under that certain Procedures
Letter dated as of the even date herewith between the Company and the Bank and
this Note and the holder hereof are entitled to all the benefits provided for
under the Procedures Letter, to which reference is hereby made for a statement
thereof. The Company hereby waives presentment and notice of dishonor. The
Company agrees to pay to the holder hereof all expenses incurred or paid by such
holder, including attorney's fees and court costs, in connection with the
collection of this Note. It is agreed that this Note and the rights and remedies
of the holder hereof shall be construed in accordance with and governed by the
laws of Illinois.

                                                 ZEFER CORP.

                                                 By: /s/ Deidre Aubuchon
                                                     --------------------
                                                     Its: Vice President,Finance
                                                         -----------------------

                                       1<PAGE>

                                                                   EXHIBIT 10.38

                                     LEASE

                                By and Between

                            EAST STREET ASSOCIATES,

                                   Landlord

                                      and

                                  ZEFER CORP.

                                    Tenant

                              Dated: June 17, 1999

                              711 Atlantic Avenue
                             Boston, Massachusetts
<PAGE>

                                TABLE OF CONTENTS
                                -----------------

<TABLE>
<S>                                                                         <C>
1.   Premises.............................................................   1

2.   Use..................................................................   1

3.   Term.................................................................   2

4.   Basic Rent...........................................................   3

5.   Operating Cost Escalation............................................   4

6.   Tax Escalation.......................................................   7

7.   Condition of the Premises............................................   9

8.   Improvements and Alterations.........................................   9

9.   Property of Tenant...................................................  12

10.  Maintenance and Repair...............................................  13

11.  Services.............................................................  14

12.  Inspection...........................................................  16

13.  Casualty and Taking..................................................  16

14.  Injury and Damage....................................................  20

15.  Indemnification......................................................  20

16.  Insurance............................................................  22

17.  Waiver of Subrogation................................................  23

18.  Assignment, Mortgaging, Subletting...................................  23

19.  Default..............................................................  25

20.  Landlord's Right to Cure.............................................  28
</TABLE>
<PAGE>

<TABLE>
<S>                                                                                                          <C>
21.  Subordination; Nondisturbance........................................................................   28

22.  Surrender of Possession; Holdover....................................................................   29

23.  Notices..............................................................................................   29

24.  Rules and Regulations................................................................................   29

25.  Quiet Enjoyment......................................................................................   30

26.  Limitation of Landlord's Liability...................................................................   30

27.  Binding Agreement....................................................................................   31

28.  Notice of Lease......................................................................................   31

29.  Brokerage............................................................................................   31

30.  Guaranty.............................................................................................   32

31.  Security Deposit.....................................................................................   32

32.  Environmental Provisions.............................................................................   33

33.  General Provisions...................................................................................   33
</TABLE>

Exhibits

                                     -ii-
<PAGE>

                                   L E A S E
                                   ---------

     This LEASE (this "Lease") is made and entered into as of this 17th day of
June, 1999 by and between EAST STREET ASSOCIATES, a Massachusetts limited
partnership with an office at 711 Atlantic Avenue, Boston, Massachusetts
(hereinafter called "Landlord"), and ZEFER CORP., a Delaware corporation
currently having an office at 105-107 South Street, Boston, Massachusetts
(hereinafter called "Tenant").

     1.  Premises. In consideration of the rents and covenants herein stipulated
         --------
to be paid and performed by Tenant and upon the terms and conditions herein
specified, Landlord hereby leases to Tenant, and Tenant hereby hires and takes
from Landlord, the following-described premises (the "Premises"):

          A portion of the building located at 711 Atlantic Avenue in Boston,
          Massachusetts (the "Building") as shown cross-hatched or outlined on
          the lease plan (the "Lease Plan") shown on Exhibit A attached hereto
          and made a part hereof, consisting of the entire sixth (6th) floor of
          the Building agreed to contain 13,500 square feet of rentable area,
          including an allocable portion of the common areas of the Building.
          The total rentable area of the Building is agreed to be 79,654 square
          feet.

     The Premises are leased together with the right of Tenant to use for its
customers, employees and visitors, in common with others entitled thereto, such
common areas and facilities in or appurtenant to the Building as required for
access to the Premises and to lavatories, in locations as Landlord may from time
to time reasonably designate and provide.  Subject to Landlord's reasonable
security requirements, Tenant shall have access to the Premises at all times.

     2.  Use. Tenant may use the Premises only for general office purposes.
         ---
Subject to Landlord's obligations set forth in Section 10, such use and
occupation shall at all times be in compliance with the ordinances of the City
of Boston, the laws of The Commonwealth of Massachusetts and the United States
of America and any regulations under any thereof. Tenant
<PAGE>

shall not use, permit or suffer anything to be done in the Premises or anything
to be brought into or kept in the Premises, in either case, which occasions
discomfort to any other tenants or occupants of the Building, or which in
Landlord's reasonable judgment may tend to impair the reputation or appearance
of the Building or tend to interfere with the proper and economic operation of
the Building by Landlord. Tenant shall not bring or permit to be brought into or
keep in or on the Premises or elsewhere in the Building, unlawful amounts of any
inflammable, combustible or explosive fluid, material, chemical or substance, or
cause or permit any odors to emanate from or permeate the Premises.

     3. Term. Subject to the terms, covenants, agreements and conditions
        ----
contained herein, Tenant shall have and hold the Premises for a term (the
"Term") commencing on the Commencement Date and expiring at the close of the
last day of the calendar month in which the day immediately preceding the fifth
(5th) anniversary of the Commencement Date shall occur (the "Expiration Date").
For purposes hereof, (a) the "Commencement Date" shall be the 30th day following
the Delivery Date or such sooner date on which Tenant first makes use of any
portion of the Premises for the conduct of business and (b) the "Delivery Date"
shall be the date on which Landlord delivers possession of the Premises to
Tenant broom clean, free and clear of other tenants and occupants and otherwise
in a condition conforming to Landlord's obligations hereunder, any furniture or
other personal property having been removed. Tenant may terminate this lease,
without further recourse to either party, by notice given to Landlord at any
time after November 15, 1999, if the Delivery Date shall not have occurred
within fifteen (15) days following receipt of such notice. In the event this
Lease is full force and effect without default by Tenant, Tenant may extend the
Term for a period of three (3) years from the Expiration Date by given at least
nine (9) months' prior written notice thereof to Landlord. The Rent for said
extension period shall be based upon and consistent with the then fair market
rental value of the

                                      -2-
<PAGE>

Premises as the same may be mutually agreed by Landlord and Tenant and, if they
have not so agreed in writing in any case within three (3) months following the
exercise of said option, the same shall be determined by appraisers, one to be
chosen by Landlord, one to be chosen by Tenant, and a third to be selected by
the two first chosen. The unanimous written decision of the two first chosen,
without selection and participation of a third appraiser, or otherwise the
written decision of a majority of three appraisers chosen and selected as
aforesaid, shall be conclusive and binding upon Landlord and Tenant. Landlord
and Tenant shall each notify the other of its chosen appraiser within thirty
(30) days following expiration of the aforesaid three (3) month period and,
unless such two appraisers shall have reached a unanimous decision within forty-
five (45) days from said expiration, they shall within a further fifteen (15)
days elect a third appraiser and notify Landlord and Tenant thereof. Landlord
and Tenant shall each bear the expense of the appraiser chosen by it and shall
equally bear the expense of the third appraiser (if any). If, as contemplated by
this Lease, Landlord and Tenant shall not have agreed upon the Rent for said
extension period on or before the Expiration Date, then said extension period
may commence; from and after such Date until the amounts of such Rent is
determined either by agreement of the parties or by appraisal, Tenant shall make
payments of such Rent at the then current rates subject to retroactive
adjustment in conformity with and within thirty (30) days of the determination
of such Rent as hereinabove set forth.

     4. Basic Rent. (a) Tenant covenants to pay to Landlord, beginning as of the
        ----------
Commencement Date and continuing thereafter during the Term of this Lease, fixed
annual rent ("Basic Rent") at the rate of $432,000 per annum. Basic Rent shall
be payable in equal monthly installments of $36,000 each, in advance, on the
first day of every calendar month during the Term hereof, subject to proration
in the case of any partial calendar month.

                                      -3-
<PAGE>

     (b)  Except as otherwise expressly set forth herein, Tenant shall pay the
Basic Rent without set-off, deduction or demand to Landlord at its address set
forth above, or at such other place as is designated in writing from time to
time by Landlord.

     5.   Operating Cost Escalation. (a) As used in this Section, these words
          -------------------------
and terms shall have the following meanings:

          (i)  "Operating Costs" shall mean all costs incurred and expenditures
        made by Landlord for the operation and management of the Building and
        the land on which the Building is situated (hereinafter collectively
        called the "Property"). Operating Costs include, without limitation,
        costs of cleaning, security, janitorial service (including costs of
        materials and equipment); utilities and other costs related to the
        provision of heat, electricity and air conditioning (excluding heat and
        air conditioning furnished to tenants other than during normal business
        hours); maintenance and repairs to the Property (including snow removal,
        landscaping, repair of heating and air conditioning equipment, elevators
        and other non-structural Building components); payments under all
        service contracts relating to the operation and maintenance of the
        Property; reasonable management fees (not in excess of 5% of collected
        rent and other income); reasonable wages, salaries, benefits, payroll
        taxes and unemployment compensation insurance for employees of Landlord
        servicing the Property or any contractor of Landlord engaged in the
        cleaning, operation, maintenance or security of the Property; insurance
        relating to the Property; auditing expenses; payments other than Taxes
        (as hereinafter defined) to the City of Boston (including, but not
        limited to, water and sewer charges, fire service fees and other user
        fees); and supplies and all other expenses customarily incurred in
        connection with the operation of similar

                                      -4-
<PAGE>

        office buildings in the downtown Boston area. If, during the Term of
        this Lease, the Landlord shall make capital expenditures necessary or
        desirable, in the opinion of the Landlord, to meet the requirements of
        applicable laws imposed after the Delivery Date or designed to increase
        the operating efficiency of the Building or to save on labor expenses or
        to replace obsolete operating equipment, there shall be included in
        Operating Costs for the year in which the capital expenditure was made
        and in each succeeding year, an annual charge of such capital
        expenditure as determined in accordance with generally accepted
        accounting principles so long as such capital expenditure can be
        expected to achieve a reasonably-corresponding reduction of other
        Operating Costs. Operating Costs, however, shall not include (i) the
        cost of capital improvements or depreciation thereof not hereinabove
        specified (including without limitation the cost of restoration
        necessitated by fire or other casualty or by the exercise of eminent
        domain), (ii) amounts paid with respect to interest on, or amortization
        of, any mortgage, (iii) attorneys' fees incurred in connection with the
        negotiation of leases with tenants of the Building or disputes with such
        tenants unrelated to the operation or maintenance of the Property, (iv)
        any expenditures for which Landlord is reimbursed by tenants or other
        third parties (other than by tenants pursuant to expense sharing
        provisions comparable hereto), (v) rent payable under any underlying
        ground lease, (vi) the cost of renovating or otherwise improving or
        decorating, painting or redecorating space for tenants or other
        occupants of the Building, (vii) off-site overhead costs associated with
        the operation of the business entity constituting Landlord, (viii)
        salaries and benefits of executive employees above the grade of Building
        Manager, (ix) brokerage commissions, (x)

                                      -5-
<PAGE>

        advertising and other marketing costs, (xi) the cost of services or work
        provided to particular tenants of the Building which are not provided to
        Tenant or which are provided to Tenant subject to payment of an
        additional charge (currently including electricity required to provide
        heat and air conditioning to tenants during normal business hours),
        (xii) amounts paid to subsidiaries or affiliates of Landlord for
        services rendered to the Property to the extent that such amounts exceed
        the competitive costs of such services, (xiii) penalties assessed on
        account of violations by Landlord of any governmental requirement or
        (xiv) the cost of remediating any hazardous materials present on the
        Property pursuant to the provisions hereof, if necessitated by the acts
        of Landlord or its agents, employees or contractors. In addition, any
        costs relating to the Property in conjunction with other properties
        under common ownership or management shall be equitably apportioned. If
        the Building is less than fully occupied during a particular calendar
        year or if all Building tenants are not receiving the same services to
        be provided to Tenant hereunder, then Operating Costs for such year
        shall be extrapolated to an amount which reasonably approximates the
        amount which would have been incurred if the Building were fully
        occupied and such services were being provided to all Building tenants.

               (ii) "Operating Escalation Statement" shall mean a statement in
        writing signed by Landlord, setting forth the amounts payable by Tenant
        for a specified computation year pursuant to this Section and providing
        reasonable written back-up for the calculation of such amount, including
        copies of any significant invoices received by Landlord.

                                      -6-
<PAGE>

     (b)  If in any calendar year occurring during the term of this Lease, the
Operating Costs for such year exceed the Operating Costs for the Operating Cost
Base Year (as defined below), Tenant shall pay to Landlord an amount equal to
16.95% of such excess (the "Operating Cost Excess"). Such amount shall be due
and payable within thirty (30) days following receipt by Tenant of the Operating
Escalation Statement for such year. If this Lease shall commence or terminate in
the middle of a calendar year, Tenant shall be liable for only that portion of
the Operating Cost Excess in respect of such calendar year represented by a
fraction the numerator of which is the number of days of the Term which falls
within the calendar year and the denominator of which is three hundred sixty-
five (365). The Operating Cost Base Year shall mean the calendar year ending on
December 31, 1999.

     6.   Tax Escalation. (a) As used in this Section, these words and terms
          --------------
shall have the following meanings:

          (i) "Taxes" shall mean all payments, all taxes, assessments and
betterments levied, assessed or imposed by any governmental authority upon or
against the Property or Building or payments in lieu thereof, but excluding
water and sewer charges. Any such assessment or betterment shall be amortized
over the longest period permitted by applicable law such that only those
installments payable on account thereof during the Term of this Lease, together
with any interest charged to Landlord, shall be deemed included as part of Taxes
hereunder. If, at any time during the Term of this Lease, any tax or excise on
rents or other taxes, however described, are levied or assessed against Landlord
with respect to the rent reserved hereunder, either wholly or partially in
substitution for, or in addition to, real estate taxes assessed or levied on the
Property or Building, or payments in lieu thereof, such tax or excise on rents
shall be included in Taxes. Notwithstanding the foregoing, Taxes shall not
include franchise, estate, inheritance, succession, capital, levy, transfer,
income or excess profits

                                      -7-
<PAGE>

taxes assessed on Landlord nor penalties or interest on payments not made by
Landlord in a timely manner.

          (ii)   "Tax Escalation Statement" shall mean a statement in writing
signed by Landlord, setting forth the amounts payable by Tenant for a specified
computation period pursuant to this Section with a copy of Landlord's tax bill
attached thereto.

          (iii)  "Fiscal Year" shall mean the fiscal year of the City of Boston.

     (b)  If in any Fiscal Year occurring during the Term of this Lease, the
Taxes for such year exceed the Taxes for the Tax Base Year (as defined below),
Tenant shall pay to Landlord an amount equal to 16.95% of such excess (the "Tax
Excess"). Such amount shall be due and payable thirty (30) days following
receipt by the Tenant of the Tax Escalation Statement. If this Lease shall
commence or terminate in the middle of a Fiscal Year, Tenant shall be liable for
only that portion of the Tax Excess in respect of such year represented by a
fraction the numerator of which is the number of days of the Term which falls
within the Fiscal Year and the denominator of which is three hundred sixty-five
(365). The Tax Base Year shall mean the Fiscal Year ending June 30, 2000.

     (c)  If, after Tenant shall have made any payment of Tax Excess, Landlord
receives a refund of any portion of Taxes paid by Landlord, Tenant's pro rata
share of such refund, less the reasonable cost of securing the same, shall be
credited by Landlord against outstanding Rent (as defined below) or other
charges due from Tenant, if any, and any balance shall be refunded to Tenant
within thirty (30) days of receipt of same by Landlord.

     (d)  Tenant shall, if, as and when required by Landlord, with each monthly
payment of Basic Rent, make such estimated payments of Operating Cost Excess and
Tax Excess in advance as Landlord shall reasonably determine to be sufficient to
provide in the aggregate a fund adequate to pay, when due, all additional rent
required pursuant to Sections 5(b) and 6(b). Any

                                      -8-
<PAGE>

deficiency shall be payable within the time set forth in said Sections, and any
surplus shall be credited against outstanding Rent or other charges due from
Tenant, if any, and any balance shall be refunded to Tenant.

     (e)  The payments required to be made by Tenant pursuant to this Section
and Section 5, together with the Basic Rent, are hereinafter collectively called
the "Rent."

     (f)  Landlord shall retain its books and records relating to the
calculation of any "Operating Escalation Statement" or a "Tax Escalation
Statement" for at least three (3) years following the rendition thereof, and
Tenant may review said books and records within one (1) year following receipt
of the applicable Statement from Landlord.

     7.   Condition of the Premises. Landlord shall, prior to the Delivery Date,
          -------------------------
(a) render operational the freight elevator in the Building, (b) install a
locking device to restrict access to the Premises from the interior Building
stairway and (c) balance the heating, ventilating and air conditioning equipment
servicing the Premises by adjusting the output of the diffusers to accommodate
the way in which space is currently configured. In all other respects, subject
to Landlord's repair obligations hereunder, Tenant shall accept the Premises
(including existing Building window blinds, which shall be retained for Tenant's
use) "as is" on the Delivery Date, and all work necessary to prepare the
Premises for occupancy by Tenant shall be performed by Tenant in accordance with
Section 8 and the other applicable provisions of this Lease. Tenant may, at its
own risk (except with respect to the negligence or willful misconduct of
Landlord or its agents, employees or contractors), enter the Premises after the
Delivery Date in order to undertake such work.

     8.   Improvements and Alterations. (a) Tenant, at its own expense, may make
          ----------------------------
alterations, additions and improvements with Landlord's prior written consent
to the interior of the Premises which are necessary or appropriate for the
conduct of Tenant's business in

                                      -9-
<PAGE>

accordance with detailed working drawings and specifications describing such
work which have been submitted in advance to and approved in writing by Landlord
along with the identity of the contractor. Such consent or approval shall not be
unreasonably withheld or delayed in the case of any proposed work of a non-
structural nature which does not affect the common areas or facilities of the
Property and is not visible from the exterior of the Premises. In addition,
Tenant shall not be required to obtain Landlord's consent to interior painting
and similar work of a purely decorative nature so long as the quality thereof
conforms to any standard Building criteria established by Landlord. Tenant shall
pay all costs of preparing plans, drawings and specifications. Such alterations,
additions and improvements (specifically excluding movable personal property
installed by Tenant) made after the date hereof are hereinafter collectively
called the "Improvements." All the Improvements, whether placed in or attached
or made to or a part of the Premises prior to or during the Term of this Lease,
shall, unless Landlord otherwise elects and except in the case of customary
trade fixtures, become and be Landlord's property and shall be and remain part
of the Premises as of the termination of the Term. Landlord shall notify Tenant
in writing at the time Landlord approves Tenant's plans for Improvements of its
election to require Tenant to remove any or all of its Improvements upon the
expiration or earlier termination of the Term. Construction of the Improvements
shall be performed diligently and in a good and workmanlike manner and shall be
expeditiously completed in compliance with all laws, ordinances, orders, rules,
regulations and requirements. All work done in connection with the Improvements
shall comply with all requirements of insurance policies maintained by Landlord
and Tenant. Tenant, at its own expense, shall procure all permits and licenses
for the Improvements required by any governing authority having jurisdiction
over the Premises and the business to be conducted in the Premises. Tenant shall
promptly pay all costs and expenses of the Improvements, and Tenant shall
indemnify the Landlord against performance liens, costs,

                                     -10-
<PAGE>

damages and expenses in connection with all Improvements. In case of damage or
destruction of any Improvements which Landlord elected not to be a portion of
the Premises during the Term of this Lease, Tenant shall have the right to
recover its loss from any insurance company with which it has insured the same.
At the end of the Term of this Lease, if not then in default hereunder, Tenant
shall remove all of its personal property other than the Improvements (except
those Improvements which Landlord elected to require Tenant to remove). If
Landlord elects to have Tenant remove the Improvements, Landlord shall not
require removal of pipes, wires and the like from walls, ceilings or floors,
provided that Tenant properly cuts, caps and disconnects such pipes and wires
and seals them off in a safe and lawful manner flush with the applicable wall,
floor and ceiling and redecorates the area in a manner substantially consistent
with the remainder of the Premises. Tenant shall maintain the Improvements in
accordance with Section 10 during the Term of the Lease and shall be responsible
for any and all damage to the Premises, the fixtures, appurtenances and
equipment of Landlord or the Building caused by the installation, malfunction or
removal of the Improvements or Tenant's Property, as defined in Section 9.

     (b)  To protect the historical and architectural integrity and appearance
of the Building, Tenant shall not install any signs on the exterior of the
Building or Premises or in the interior of the Premises if visible from the
exterior of the Premises except as permitted by this paragraph. All signs or
lettering, if any, visible from the exterior of the Building or from the lobby,
public corridors or in any other common area or public place must be submitted
to Landlord for written approval of the size, color, design and location of such
signs or lettering before installation, which approval shall not be unreasonably
withheld or delayed. Tenant may hang its own window blinds or curtains in the
Premises, subject to Landlord's prior written approval, which approval shall not
be unreasonably withheld or delayed. Landlord shall include

                                     -11-
<PAGE>

Tenant's name and the floor location of the Premises in any directory maintained
by Landlord in the lobby of the Building.

     (c)  Subject to the provisions hereof otherwise applicable to the making of
alterations, additions and improvements in the Premises together with such
additional requirements as Landlord may reasonably prescribe, Tenant may install
cabling and wiring through vertical shafts of the Building in order to service
equipment located in the Premises. Notwithstanding the foregoing, Landlord shall
neither unreasonably withhold or delay any consent required in the case of, nor
obligate Tenant to furnish detailed working drawings and specifications
describing, such installations.

     9. Property of Tenant.  Subject to the provisions of this Section 9,
        ------------------
Tenant may place office fixtures, office equipment and the like ("Tenant's
Property") in the Premises. Tenant shall not place a load upon any floor of the
Premises exceeding the floor load per square foot area which such floor was
designed to carry and which is allowed by law. Business machines and mechanical
equipment and Tenant's other personal property shall be placed and maintained by
Tenant at its expense in settings sufficient to absorb and prevent vibration,
noise and annoyance. Except in case of the negligence or willful misconduct of
Landlord or its agents, employees or contractors, Tenant covenants and agrees
that all Tenant's Property of every kind, nature and description which may be in
or upon the Premises or Building, in the public corridors, or on the sidewalks,
area ways and approaches adjacent thereto, during the Term hereof, and any
movement of Tenant's Property, shall be at the sole risk and hazard of Tenant,
and Tenant hereby indemnifies and agrees to save Landlord harmless from and
against any liability, loss, injury, claim or suit resulting directly or
indirectly therefrom except to the extent caused by the negligence or willful
misconduct of Landlord or its agents, employees or contractors as aforesaid.

                                     -12-
<PAGE>

     10.  Maintenance and Repair. (a) Subject to Landlord's repair obligations
          ----------------------
hereunder, Tenant shall, at its sole cost and expense, maintain the Premises in
as good order, condition and repair as the same were in on the Delivery Date or
may have been put in thereafter, reasonable wear and tear and damage by fire and
other casualty excepted.  Tenant, at its own expense, shall supply all light
bulbs, tubes or similar devices for lighting the Premises.  Landlord agrees to
change all such bulbs, tubes or similar devices.

     (b) Landlord shall: (i) keep the Building structure (including without
limitation the roof) and the plumbing, electrical, heating, ventilating and air
conditioning systems and utility service lines of the Building servicing the
Premises in good and operating condition and repair (except that Tenant shall be
responsible for the cost of any repair or replacement occasioned by any act or
neglect of Tenant, its servants, agents, customers, contractors, employees or
licensees); (ii) keep the sidewalks, common corridors, stairways, elevators and
all other public portions of the Building in good and operating condition and
repair and in a reasonably clean and safe condition; and (iii) comply with
applicable governmental rules, regulations, laws and ordinances affecting the
Building or Tenant's ability to use the Premises for general office purposes,
unless a violation is caused by Tenant or any party claiming by through or under
Tenant.  Landlord reserves the right to interrupt, curtail, stop or suspend the
furnishing of any services and the operation of the plumbing, electrical,
heating, ventilating and air conditioning systems when necessary by reason of
accident or emergency or for repairs, alterations, replacements or improvements
which may become necessary or when it cannot secure supplies or labor, or by
reason of any other cause beyond its reasonable control, without liability or
any abatement of Rent being due thereby.  In exercising its rights set forth in
the preceding sentence, Landlord hereby agrees to use reasonable efforts to not
materially interfere with Tenant's use of the Premises.  Notwithstanding the
foregoing, if, as a result of any such interruption, curtailment,

                                     -13-
<PAGE>

stoppage or suspension, the Premises are substantially untenantable for thirty
(30) consecutive days, Tenant may, by notice to Landlord at any time thereafter
(unless, within five (5) days following receipt of such notice, the Premises are
no longer substantially untenantable as aforesaid), elect to terminate this
Lease with the same force and effect as if the Term had expired.

     11.  Services. (a) Landlord shall provide:
          --------

          (i)   Access to the Premises from the Building lobby during regular
Building hours (7:00 a.m. to 6:00 p.m.) on business days (Saturdays, Sundays and
legal Massachusetts holidays excepted) and, at all other times, controlled
access under conditions which will insure the security of the Building.

          (ii)  Necessary elevator facilities.

          (iii) Heat and air conditioning to the common areas of the Building
and heat and air conditioning reasonably required for the comfortable occupancy
of the Premises during normal seasonal heating periods on business days from
7:00 a.m. to 6:00 p.m. and on Saturdays from 7:00 a.m. to 1:00 p.m. (except
legal Massachusetts holidays). The Landlord shall furnish heat and air
conditioning beyond the above stated hours, provided that notice requesting such
service is delivered to Landlord before noon on the business day when such
service is required for that evening, and by noon of the preceding business day
when such service is required on a Saturday, Sunday or holiday. Landlord's
reasonable charge for supplying such additional service (currently $35.00 per
hour) shall be paid by Tenant or, alternatively, shall be shared proportionately
between Tenant and other tenants, if any, located in the relevant zone who have
requested and are receiving the benefit of such service at the same time as
Tenant (it being understood and agreed, however, that the air conditioning
equipment currently servicing the Premises does not also service any other
rentable area in the Building). Air conditioning and

                                     -14-
<PAGE>

heating of the Premises will be separately metered by Landlord at Landlord's
sole cost and expense, and Tenant shall be responsible for paying all
electricity required to provide such air conditioning and heating.

          (iv)  Cleaning and janitor service in scope, quality and frequency is
described in Exhibit C attached hereto and made a part hereof (the "Cleaning
Specifications"), provided the Premises are kept in good condition by Tenant.

          (v)   Hot and cold running water, liquid soap, toilet tissue and paper
towels for washrooms and lavatories.

          (vi)  Electricity for normal lighting of the main lobby, elevators,
washrooms and stairs, but not for the Premises, on a 24 hour/day, 365 day/year
basis.

          (vii) Removal of snow and ice from the entry and sidewalks to the
Building.

     (b)  Tenant shall purchase the electrical energy required by Tenant for
operation of the lighting fixtures, equipment, appliances and heating and air
conditioning systems servicing the Premises directly from the public utility
company servicing the Building as determined by separate meters.  Landlord shall
not be liable in any way to Tenant for any failure or defect in the supply or
character of electrical energy furnished to the Premises by reason of any
requirement, act or omission of said public utility company.  Tenant's use of
electrical energy in the Premises shall not at any time exceed the capacity of
any of the electrical conductors and equipment in or otherwise serving the
Premises.

     (c)  In the event Tenant wishes to provide outside services for the
Premises over and above those services to be provided by Landlord as set forth
herein ("Outside Services"), Tenant shall first obtain the prior written
approval of Landlord, which approval shall not be unreasonably withheld or
delayed, for the installation and/or utilization of such services. Outside
Services shall include, but not be limited to, cleaning services, television,
so-called "canned

                                     -15-
<PAGE>

music" services, security services and the like, excluding the use of caterers,
couriers and other vendors whose services are routinely engaged in connection
with specified functions or transactions.  If Landlord approves the installation
and/or utilization of Outside Services, such installation and utilization shall
be at Tenant's sole cost, risk and expense except in the case of the negligence
or willful misconduct of Landlord or its agents, employees or contractors.

     12.  Inspection. Landlord and its authorized representatives shall have the
          ----------
right at all reasonable times and with prior notice to Tenant (except in case of
emergency) to enter the Premises to inspect the same, to make repairs or
replacements therein as required by this Lease or requested by Tenant, to
exhibit the Premises to prospective tenants (but only during the final twelve
(12) months of the Term) or others, and to introduce conduits and pipes or ducts
as may be necessary with all repair and clean up to be performed by Landlord
immediately upon completion of work; provided, however, that Landlord shall use
all reasonable effort to not unreasonably disturb Tenant's use and occupancy and
to afford an opportunity for an employee of Tenant to be present while Landlord
or its authorized representatives remain in the Premises.  The exercise of any
such right shall not be deemed an eviction or disturbance of Tenant's use or
possession unless such disruptions are actually continuous and actually cause
Tenant's business to cease operations.

     13.  Casualty and Taking. (a) If the Premises or any part thereof shall be
          -------------------
damaged by fire or other casualty, Landlord shall proceed with reasonable
diligence, and at the expense of Landlord, to repair or cause such damage to be
repaired, provided however that Landlord shall in no event be responsible for
any repairs or replacements of (i) the Improvements which Landlord elected not
to be a portion of the Premises or of (ii) Tenant's Property.  If the Premises
or any part thereof shall have been rendered unfit for use and occupation
hereunder by reason of such damage, the Basic Rent or a just and proportionate
part thereof, according to the nature and

                                     -16-
<PAGE>

extent to which the Premises shall have been so rendered unfit, shall be
suspended or abated from the time of such damage until the Premises (except as
to the property which is to be repaired by or at the expense of Tenant) shall
have been restored as nearly as practicably may be to the condition in which
they were immediately prior to such fire or other casualty and a certificate of
occupancy issued permitting Tenant's use of the Premises. Landlord shall not be
liable for delays in the making of any such repairs which are due to
governmental regulations, casualties and strikes, and other causes beyond the
control of Landlord, nor shall Landlord be liable for any inconvenience or
annoyance to Tenant or injury to the business of Tenant resulting from
reasonable delays in repairing such damage. In case the Building or at least 25%
thereof is so damaged by such fire or other casualty that substantial alteration
or reconstruction (which may reasonably be expected to take nine months or
longer of actual construction time to complete) of the Building shall be
required, then, whether or not the Premises shall have been damaged by such fire
or other casualty, this Lease and the Term hereof may be terminated at the
election of Landlord or Tenant by a notice in writing of its election so to
terminate, which termination shall be effective not less than thirty (30) days
after the day on which such termination notice is received. In the event of any
such termination, this Lease and the Term hereof shall expire as of such
effective termination date and the Rent shall be apportioned as of such date;
and if the Premises or any part thereof shall have been rendered unfit for use
and occupation by reason of such damage, the Basic Rent for the period from the
date of the fire or other casualty to the effective termination date, or a just
and proportionate part thereof, according to the nature and extent to which the
Premises shall have been so rendered unfit, shall be abated and any security
deposits and other expense deposits shall be returned to the extent that such
deposits represent a period after the expiration of the Term.

                                     -17-
<PAGE>

     (b)  In the event that the Premises or any part thereof, or the whole or
any substantial part of the Building, or the access thereto, shall be taken or
appropriated by eminent domain or shall be condemned for any public or quasi-
public use, or (by virtue of any such taking, appropriation or condemnation)
shall suffer any damage (direct, indirect or consequential) for which Landlord
or Tenant shall be entitled to compensation, then (and in any such event) this
Lease and the Term hereafter may be terminated at the election of Landlord by a
notice in writing of its election so to terminate which shall be given by
Landlord to Tenant within sixty (60) days following the date on which Landlord
shall have received notice of such taking, appropriation or condemnation. In
that event, the termination date is to be sixty (60) days from Tenant's receipt
of notice from Landlord. If the entire Premises or such portion thereof or the
access thereto shall be so taken, appropriated or condemned, such that Tenant
shall be precluded from effectively utilizing the Premises, then (and in any
such event) this Lease and the Term hereof may be terminated at the election of
Tenant by a notice in writing of its election so to terminate which shall be
given by Tenant to Landlord within sixty (60) days following the date on which
Tenant shall have received notice of such taking, appropriation or condemnation.
Upon the giving of any such notice of termination (either by Landlord or Tenant)
this Lease and the Term hereof shall terminate on or retroactively as of the
date on which Landlord or Tenant, as the case may be, shall be required to
vacate any portion of the area so taken, appropriated or condemned or shall be
deprived of the means of access thereto; provided, however, that Landlord may in
Landlord's notice of termination elect to terminate this Lease and the Term
hereof retroactively as of the date on which such taking, appropriation or
condemnation became legally effective.  In the event of such termination, this
Lease and the Term hereof shall expire as of such effective termination date and
the Basic Rent shall be apportioned as of such date and any

                                     -18-
<PAGE>

security deposits and other expense deposits shall be returned to the extent
that such deposits represent a period after the expiration of the Term.

     (c) If neither party (having the right so to do) elects to terminate this
Lease and the Term hereof as provided in paragraph (b) above, Landlord shall,
with reasonable diligence and at Landlord's expense, restore the remainder of
the Premises (but not the Improvements which Landlord elected not to be a
portion of the Premises or any of Tenant's Property), or the remainder of the
means of access, as nearly as practicably to the condition as obtained prior to
such taking, appropriation or condemnation, in which event the Rent shall be
adjusted in a manner such that (i) a just proportion of the Basic Rent,
according to the nature and extent of the taking, appropriation or condemnation
and the resulting permanent injury to the Premises and the means of access
thereto, shall be permanently abated, and (ii) a just proportion of the
remainder of the Basic Rent, according to the nature and extent of the taking,
appropriation or condemnation and the resultant injury sustained by the Premises
and the means of access thereto, shall be abated until what remains of the
Premises (other than said Improvements or Tenant Property) and the means of
access thereto shall have been restored as fully as may be for permanent use and
occupation by Tenant hereunder.  Landlord shall not be liable for any delays in
such restoration which are due to governmental regulations, casualties, strikes,
unavailability of labor or materials, or other causes beyond Landlord's control,
nor shall Landlord be liable for any inconvenience or annoyance to Tenant or
injury to the business of Tenant resulting from reasonable delays in such
restoration.  Landlord expressly reserves and Tenant hereby assigns to Landlord
all rights to compensation and damages created, accrued or accruing by reason of
any such taking, appropriation or condemnation, but not including relocation
assistance payments by a governmental agency or entity nor any compensation for
damages to Tenant's property.

                                     -19-
<PAGE>

     (d) If the Premises or any part thereof or the access thereto shall be
taken, appropriated or condemned for any temporary use (i) this Lease shall be
and remain unaffected thereby and Tenant shall continue to pay the full amount
of the Rent hereunder, (ii) Tenant shall be entitled to receive for itself any
award made for such use allocable to the Term of this Lease, and (iii) Tenant,
to the extent of any award made under (ii) above, shall be responsible for any
repairs necessary to restore the Premises to their condition prior to such
taking, appropriation or condemnation, provided that if any such taking,
appropriation or condemnation extends beyond the Term of this Lease, the costs
of such repairs shall be allocated between Landlord and Tenant in proportion to
the amount of any award each receives.  Any taking, appropriation or
condemnation continuing in excess of one year shall be deemed to be a permanent
taking, appropriation or condemnation and shall be governed by paragraphs (b)
and (c) of this Section 13.

     14.  Injury and Damage.  Landlord shall not be liable for any injury or
          -----------------
damage to persons or property resulting from fire, explosion, falling plaster,
steam, gas, electricity, electrical disturbance, water, rain or snow or leaks
from any part of the Building or from the pipes, appliances or plumbing works or
from the roof, street or subsurface or from any other place or by dampness or by
any other cause of whatever nature, unless caused by or due to the act,
omission, fault, negligence or misconduct of Landlord, or its agents, employees
or contractors; nor shall Landlord or its agents be liable for any such damage
caused by other tenants or persons in the Building or caused by construction
operations of any private, public or quasi-public person.

     15.  Indemnification. (a) Tenant hereby indemnifies and covenants to save
          ---------------
Landlord harmless from and against any and all claims, liabilities or penalties
asserted by or on behalf of any person, firm, corporation or public authority:
(i) on account of or based upon any injury to

                                     -20-
<PAGE>

person, or loss of or damage to property, sustained or occurring on the Premises
on account of or based upon the act, omission, fault, negligence or misconduct
of Tenant or its agents, employees and invitees; (ii) on account of or based
upon any injury to person, or loss of or damage to property, sustained or
occurring in or about the Property and other than on the Premises (and, in
particular, without limiting the generality of the foregoing, on or about the
elevators, stairways, public corridors, sidewalks, concourses, arcades,
approaches, area ways, roof or other appurtenances and facilities used in
connection with the Building or the Premises) arising out of the use or
occupancy of the Building or the Premises by Tenant or by any person claiming
by, through or under Tenant, and caused by the act, omission, fault, negligence
or misconduct of Tenant or its agents, employees and invitees, and in addition
to and not in limitation of the foregoing subdivision (i); and (iii) on account
of or based upon (including monies due on account of) any work or thing
whatsoever done by or on behalf of Tenant or any party claiming by, through or
under Tenant on the Premises; and, in respect of any of the foregoing, from and
against all costs, expenses (including, without limitation, reasonable
attorneys' fees) and liabilities incurred in or in connection with any such
claim, or any action or proceeding brought thereon. If any action or proceeding
be brought against Landlord by reason of any such claim, Tenant, upon notice
from Landlord, shall, at Tenant's expense, resist or defend such action or
proceeding and employ counsel therefor reasonably satisfactory to Landlord, it
being agreed that such counsel as may act for insurance underwriters of Tenant
engaged in such defense shall be deemed satisfactory.

     (b) Landlord hereby indemnifies and covenants to save Tenant harmless from
and against any and all claims, liabilities, penalties, damages, losses, costs
and expenses (including reasonable attorneys' fees) asserted against or incurred
by Tenant on account of or based upon the act, omission, fault, negligence or
misconduct of Landlord or its agents, contractors or

                                     -21-
<PAGE>

employees; and, in case any action or proceeding be brought against Tenant by
reason of any of the foregoing, Landlord upon notice from Tenant shall at
Landlord's expense resist or defend such action or proceeding and employ counsel
therefor reasonably satisfactory to Tenant, it being agreed that such counsel as
may act for insurance underwriters of Landlord engaged in such defense shall be
deemed satisfactory.

     (c)  Each party, upon receiving notice of any claim against which the other
party has agreed to provide indemnification pursuant to this Section or
elsewhere in this Lease, shall promptly so notify the other party.

     16.  Insurance. (a) Tenant agrees to maintain public liability insurance in
          ---------
an amount not less than $2,000,000.00 per occurrence for personal injuries or
deaths occurring in or about the Premises and the Building and property damage
liability insurance in an amount not less than $2,000,000.00 and to submit and
maintain copies of such policies with Landlord. The insurers under such policies
and the coverage afforded thereunder shall be reasonably satisfactory to
Landlord and such policies shall name as insured parties Landlord and Tenant and
any party holding an interest to which this Lease may be subordinated pursuant
to Section 21, as their interests may appear, and shall provide twenty (20)
days' prior written notice to Landlord of lapse or cancellation.

     (b)  Tenant shall not do or omit to do or keep anything in, upon or about
the Premises, the Building or any adjacent areas which may prevent the obtaining
of any fire, liability or other insurance upon or written in connection with the
Premises or the Building or which may make any such insurance void or voidable
or otherwise invalidate the obligations of the insurer contained therein, or
which may increase the rate of any such insurance over that normally applicable
to office buildings.  Tenant agrees to pay to Landlord, upon demand and
provision by Landlord of reasonable written documentation thereof, the amount of
any extra premiums which

                                     -22-
<PAGE>

results from Tenant's failure to comply with the foregoing provisions or from
the business carried on in the Premises by Tenant, whether or not Landlord has
consented to such business.

     17.  Waiver of Subrogation. Landlord and Tenant shall each use its best
          ---------------------
efforts to cause all policies of fire, extended coverage, and other physical
damage insurance covering the Premises, the Building, and any property therein
to contain the insurer's waiver of subrogation and consent to preloss waiver of
rights over the insured. Effective only when permitted by the policy or when
such a clause is commercially available at no additional cost or premium (unless
the other party agrees to pay the same), Landlord and Tenant respectively waive
all claims and rights to recover against the other in event of loss or damage
caused by a peril (including without limitation vandalism or malicious mischief)
coverage against which is afforded by a so-called "All Risk" policy, whether or
not actually procured and without regard to any deductible.

     18.  Assignment, Mortgaging, Subletting. (a) Tenant covenants and agrees
          ----------------------------------
that neither this Lease nor the Term hereof, nor the estate hereby granted, nor
any interest herein or therein, will be assigned, mortgaged, pledged, encumbered
or otherwise transferred, and that neither the Premises, nor any part thereof,
will be encumbered in any manner by reason of any act or omission of Tenant, or
used or occupied, or permitted to be used or occupied, by anyone other than
Tenant and its employees, or for any use or purpose other than as above stated,
or be sublet, or offered or advertised for subletting, without in each case,
obtaining Landlord's prior written consent. Notwithstanding the foregoing,
Tenant shall have the privilege of assigning this Lease to, or making a sublease
or other occupancy arrangement with, any entity which is a corporate parent,
subsidiary, affiliate or successor of Tenant by way of merger or consolidation
or the acquisition of all or substantially all of Tenant's assets as a going
concern, subject, however, in all respects to all the covenants, agreements,
terms, provisions and conditions contained in this Lease; no such assignment
shall be valid unless, simultaneously therewith, Tenant shall deliver

                                     -23-
<PAGE>

to Landlord an executed counterpart of said assignment and the assignee shall
deliver to Landlord an agreement in form and substance reasonably satisfactory
to Landlord which contains an appropriate covenant of assumption by such
assignee, and no such assignment to a successor shall be valid unless prior to
said assignment Tenant shall have submitted to Landlord financial statements or
other material satisfactory to Landlord indicating that such assignee has
financial resources and a general business reputation comparable to those of
Tenant immediately prior to such assumption.

     (b)  If this Lease is assigned, or if the Premises or any part thereof be
sublet or occupied by anybody other than Tenant and its employees, Landlord may
collect the rents from such assignee or, if Tenant is in default hereunder
beyond the applicable grace period, from such subtenant or occupant, as the case
may be, and apply the net amount collected to the Rent herein reserved, but no
such assignment, subletting, occupancy or collection shall be deemed a waiver of
the requirements set forth in subparagraph (a) of this Section, the acceptance
by Landlord of such assignee, subtenant or occupant, as the case may be, as a
tenant, or a release of Tenant from the future performance by Tenant of its
covenants, agreements and obligations contained in this Lease.  The consent by
Landlord to an assignment or subletting shall not in any way be construed to
relieve Tenant from primary liability under this Lease or from obtaining the
express consent in writing of Landlord to any further assignment or subletting.
No assignment, subletting or use of the Premises shall affect the purpose for
which the Premises may be used as stated in Section 2.

     (c)  Tenant further covenants and agrees that it will not sublease space
from or take an assignment of a lease covering space in the Building from any
other Building tenant or sublease to or assign this Lease to any other Building
tenant without prior written consent from Landlord, which consent shall not be
unreasonably withheld or delayed (unless Landlord is able to make

                                     -24-
<PAGE>

available when needed and for at least the same duration space of comparable
size elsewhere in the Building).

     (d)  Except as otherwise hereinabove set forth, Landlord shall not
unreasonably withhold or delay its consent to a proposed subletting of the
Premises, provided however that Landlord may, in lieu of such consent, elect to
terminate this Lease immediately prior to the effective date of any proposed
subletting with the same force and effect as if the term hereof had expired, and
provided further that, if Landlord consents to the subletting of the Premises in
whole or in part, Tenant shall pay to Landlord 50% of any rent or other
consideration received from the subtenant in excess of the rent and other
charges payable hereunder (allocated to the sublet area on a prorata basis), net
of any brokerage commissions and other expenses reasonably incurred by Tenant
with respect to the subject transaction.

     (e)  Any consent required from Landlord pursuant to this Section shall be
deemed to have been granted unless Landlord informs Tenant to the contrary
within fifteen (15) days following Landlord's receipt of Tenant's written
request therefor, so long as such request expressly and conspicuously recites
the effect of Landlord's failure to respond thereto as aforesaid.

     19.  Default. (a) If (i) Tenant shall default in the payment of the Basic
          -------
Rent or any other charges or sums due hereunder and such default shall continue
for ten (10) days after written notice thereof by Landlord to Tenant, or (ii)
Tenant shall default in the performance of any other of its obligations and such
default shall continue for thirty (30) days after written notice thereof by
Landlord to Tenant (except that if Tenant cannot reasonably cure any such
default within said thirty (30) day period, this period may be extended for a
reasonable time, provided that Tenant commences to cure such default within the
thirty (30) day period and proceeds diligently thereafter to effect such cure),
or (iii) Tenant shall abandon the Premises (as

                                     -25-
<PAGE>

distinguished from ceasing operations therein while seeking an acceptable
assignee or subtenant), or (iv) Tenant shall file a petition under any
bankruptcy, insolvency law or code, or (v) such a petition filed against Tenant
is not dismissed within sixty (60) days, or (vi) Tenant shall be adjudicated
bankrupt or insolvent according to the law, or (vii) Tenant shall make any
assignment for the benefit of creditors, or (viii) Tenant shall file any
petition seeking a reorganization, arrangement or similar relief, or (ix) a
receiver, custodian, trustee or similar agent of the Premises or of all or a
substantial part of Tenant's assets shall be authorized or appointed, or (x)
Tenant's interest in this Lease is taken upon execution or other process of law
in any action against Tenant, then Landlord may lawfully enter the Premises and
repossess the same as the former estate of Landlord, or terminate this Lease and
the Term hereof upon five (5) day written notice to Tenant and, in either event,
expel Tenant and these claiming through or under Tenant, and remove their
effects (forcibly, if necessary), without being deemed guilty of any manner of
trespass and without prejudice to any other remedy which Landlord may have for
arrears of Basic Rent and other charges and sums due hereunder or proceeding on
account of breach of covenant, and upon entry or notice as aforesaid, this Lease
shall terminate. In case of any default by Tenant hereunder, Tenant shall pay
all costs of enforcing the Landlord's rights under this Lease (including,
without limitation, reasonable attorneys' fees and expenses). In addition,
following the termination of this Lease on account of such default as aforesaid,
Tenant shall pay damages, as Landlord may elect, equivalent to either (i) the
amount by which, at the termination of the Term of the Lease, the aggregate of
the Rent and other sums payable hereunder projected over a period from such
termination until the normal expiration date of the Term (specifically excluding
the extension period referenced in Section 2 unless Tenant shall have exercised
its option with respect thereto), exceeds the aggregate projected fair market
rental value of the Premises for such period, reasonably discounted in each case
to present value, or (ii)

                                     -26-
<PAGE>

an amount equal to the Rent and other sums which would have been payable had the
Lease not so terminated (subject to offset for net rents actually received from
reletting after subtraction of the reasonable expenses of reletting, Landlord
hereby agreeing to exercise good faith efforts to mitigate damages hereunder)
payable upon the due dates as specified herein, whichever the Landlord shall
elect.

     (b)  Landlord may bring legal proceedings for the recovery of such damages,
or any installments thereof, from time to time at its election, and nothing
contained herein shall be deemed to require Landlord to postpone suit until the
date when the Term of this Lease would have expired if it had not been
terminated hereunder.

     (c)  Nothing herein contained shall be construed as limiting or precluding
the recovery by Landlord from Tenant of any sums or damages (including, without
limitation, reasonable attorneys' fees and expenses) to which, in addition to
the damages particularly provided above, Landlord may lawfully be entitled by
reason of any default hereunder on the part of Tenant.  Landlord and Tenant
agree that, for the purpose of computing damages, the Tax Excess payments and
Operating Cost Excess payments for the period between the termination of the
Term of this Lease pursuant to this Section and the normal expiration date shall
be computed by multiplying the sum of the Tax Excess payment for the Fiscal Year
immediately preceding the Fiscal Year in which termination occurs and the
Operating Cost Excess payments for the year immediately preceding the year in
which termination occurs times the number of years and any fraction thereof
remaining of the full Term hereby granted on the assumption that the amount of
such Tax Excess payment and Operating Cost Excess payment for the immediately
preceding year would have remained constant for each subsequent year during the
full Term of this Lease.  If this Lease and the Term hereof shall terminate
pursuant to this Section prior to the determination of the initial Tax Excess
payment and Operating Costs the Tax Excess payment

                                     -27-
<PAGE>

and Operating Cost Excess payment shall be reasonably estimated by Landlord, in
its sole discretion, based on historical costs and experience.

     (d)  After more than two occasions during any consecutive twelve (12) month
period where payments of Rent, including additional rent, Tax Excess and
Operating Cost Excess and any other obligations of Tenant are not paid on the
date due, then such late payments shall, at the option of Landlord after notice
to Tenant, bear interest at the rate equal to the "prime rate" from time to time
established by BankBoston plus two percent (2%) per annum from the due date and
shall be compounded monthly.

     20.  Landlord's Right to Cure. If Tenant shall default in the observance or
          ------------------------
performance of any term, covenant or condition on its part to be observed or
performed under this Lease, Landlord, without being under any obligation to do
so and without thereby waiving such default, may remedy such default for the
account and at the expense of Tenant, immediately and without notice in case of
emergency, or in any other case, if Tenant shall fail to remedy such default
within the applicable grace period. If Landlord makes any expenditures or incurs
any obligations for the payment of money in connection therewith, including, but
not limited to, reasonable attorneys fees, such sums paid or obligations
incurred, with interest at the rate of interest set forth in Section 19, shall
be paid to Landlord by Tenant as Rent hereunder.

     21.  Subordination; Nondisturbance. (a) This Lease is subject and
          -----------------------------
subordinate in all respects to all mortgages and other existing matters of
record affecting the Building or the Property as of the date hereof. Tenant
agrees at the request of Landlord to subordinate this Lease to any mortgage,
ground lease, or other matter of record placed upon or affecting this Lease, the
Building, the Property or Landlord's interest or estate therein and to recognize
the holder thereof or any other person acquiring title to the Property as
Landlord, provided such holder or person

                                     -28-
<PAGE>

recognizes this Lease subject to a default by Tenant hereunder. Tenant agrees to
execute and deliver any appropriate instruments necessary to carry out the
foregoing provisions.

     (b)  Landlord agrees to use its diligent efforts to obtain from the current
holder of the first mortgage with respect to the Property (the "First Mortgage")
a nondisturbance agreement in such holder's usual form within ninety (90) days
from the date hereof, provided however that Tenant shall be required to pay any
charge customarily imposed by such holder therefor.

     22.  Surrender of Possession; Holdover. (a) At the expiration or earlier
          ---------------------------------
termination of the Term of this Lease, Tenant shall remove Tenant's Property and
shall peaceably yield up to Landlord the Premises in the condition required by
Section 10 (a), together with any Improvements (unless otherwise requested by
Landlord pursuant to the provisions of this Lease).

     (b)  If Tenant remains in the Premises beyond the expiration or earlier
termination of the Term of this Lease, such holding over shall not be deemed to
create any tenancy, but the Tenant shall be a Tenant-at-Sufferance only and
shall pay rent to Landlord at a daily rate in an amount equal to one and one
half times the daily rate of the Rent and other sums payable under this Lease as
of the last day of the Term of this Lease.

     23.  Notices. Any notice or demand by Tenant to Landlord shall be served by
          -------
registered or certified mail addressed to Landlord at the address first above
indicated, unless otherwise directed in writing by Landlord, and any notice or
demand by Landlord to Tenant shall be served by registered or certified mail, in
person, or by recognized overnight or other delivery service addressed to Tenant
at the address first above indicated until the Commencement Date and thereafter
the Premises, unless otherwise directed in writing by Tenant.  Any such notice
or demand shall be in writing and shall be deemed effective upon receipt or
refusal thereof.

     24.  Rules and Regulations. Tenant shall faithfully observe and comply with
          ---------------------
the Rules and Regulations set forth on Exhibit B attached hereto and made a part
hereof and such other and

                                     -29-
<PAGE>

further reasonable Rules and Regulations as Landlord hereafter at any time or
from time to time may make and may communicate in writing to Tenant at least
five (5) days before the effective date thereof and which apply to all other
tenants in the Building and which are commercially reasonable, which in the
judgment of Landlord shall be necessary for the reputation, safety, care or
appearance of the Building, or the preservation of good order therein, or the
operation or maintenance of the Building, or any equipment relating thereto, or
the comfort of tenants or others in the Building. Nothing contained in any such
Rules and Regulations shall be deemed to prohibit the hanging of customary
artwork, professional certificates and the like. If this Lease shall conflict
with any such Rules and Regulations, the provisions of this Lease shall control.
Landlord shall not have any duty or obligation to enforce the Rules and
Regulations or the terms, covenants or conditions in any other lease as against
any other tenant (so long as Landlord does not unreasonably discriminate among
tenants), and Landlord shall not be liable to Tenant for violation of such Rules
and Regulations, terms, covenants or conditions by other tenants, their
servants, employees, agents, visitors, invitees or licensees.

     25.  Quiet Enjoyment. The Tenant, on paying the Rent and other sums payable
          ---------------
hereunder and performing the covenants of this Lease on its part to be
performed, shall and may peaceably and quietly have, hold and enjoy the Premises
for the Term of this Lease.

     26.  Limitation of Landlord's Liability. The term "Landlord," as used in
          ----------------------------------
this Lease, so far as covenants or obligations to be performed by Landlord are
concerned, shall be limited to mean and include only the owner or owners at the
time in question of the Building, and in the event of any transfer or transfers
of title to said Building, the Landlord herein named (and in case of any
subsequent transfers or conveyances, the then grantor) shall be automatically
freed and relieved from and after the date of such transfer or conveyance of all
liability as respects the performance of any covenants or obligations on the
part of the Landlord contained in this Lease

                                     -30-
<PAGE>

thereafter to be performed, it being intended hereby that the covenants and
obligations contained in this Lease on the part of Landlord shall, subject as
aforesaid, be binding on the Landlord, its successors and assigns, only during
and in respect of their respective successive periods of ownership of the
Property. Tenant, its successors and assigns, agrees it shall not assert nor
seek to enforce any claim for breach of this Lease against any of Landlord's
assets other than Landlord's equity interest in the Building and in the rents,
issues and profits thereof (including the proceeds of any sale of such
interest), and Tenant agrees to look solely to such interest for the
satisfaction of any liability of or claim against Landlord under this Lease, it
being specifically agreed that in no event whatsoever shall Landlord (which term
shall include, without limitation, any beneficiary of any trust of which
Landlord is a trustee) ever be personally liable for any such liability.

     27.  Binding Agreement.  This Lease shall bind and inure to the benefit
          -----------------
of the parties hereto and such respective heirs, representatives, successors or
assigns as are permitted by this Lease. This Lease contains the entire agreement
of the parties and may not be modified except by an instrument in writing
executed by both Tenant and Landlord.

     28.  Notice of Lease.  Tenant agrees that it will not record this Lease.
          ---------------
Landlord and Tenant shall, upon request of either, execute and deliver a notice
of this Lease in such applicable form as may be permitted by applicable statute.

     29.  Brokerage. Landlord and Tenant each represents and warrants to the
          ---------
other that it has dealt with no broker except CB Richard Ellis - NE Partners, LP
and Avalon Partners, d/b/a CRESA Partners (the "Brokers"), in connection with
this transaction. Landlord hereby agrees to pay any compensation which may be
due by it to the Brokers. Tenant agrees to hold harmless and indemnify Landlord
from and against any and all cost, expense, or liability for any

                                     -31-
<PAGE>

compensation, commissions and charges claimed by any other broker or agent
claiming to have dealt with Tenant in connection with this Lease or the
negotiation thereof.

     30.   Guaranty. As used in clauses (iv), (v), (vi), (vii), (viii) and (ix)
           --------
of Section 19(a), the term "Tenant" shall also be deemed to refer to
any guarantor of Tenant's obligations hereunder.

     31.   Security Deposit. A deposit in the amount of $432,000 (the "Security
           ----------------
Deposit") shall be held by Landlord during the Term of this Lease as security
for the full, faithful and punctual performance of Tenant's covenants hereunder,
it being understood that the Security Deposit is not to be considered prepaid
rent, nor shall damages be limited to the amount of the Security Deposit, nor
shall Landlord be required, because of the Security Deposit, to waive its right
to terminate this Lease upon a default. The Security Deposit (if held in cash)
shall not earn interest and need not be kept in a segregated account or
otherwise escrowed. The Security Deposit, or any balance thereof, shall be
refunded to Tenant, subject to Tenant's satisfactory compliance herewith, within
thirty (30) days following the end of the Term of this Lease. Tenant shall be
entitled to pay the Security Deposit in the form of an irrevocable letter of
credit subject to the following terms and conditions. Said letter of credit
shall be issued by Silicon Valley Bank or any other commercial bank reasonably
acceptable to Landlord and shall be in a form reasonably satisfactory in all
respects to Landlord. In the event of any default by Tenant beyond the
applicable grace period, Landlord shall be entitled to receive from the issuer
of such letter of credit upon demand so much of the amount which may be drawn
therefrom as shall be necessary to cure such default and compensate Landlord for
all losses, liabilities, damages and other expenses, including without
limitation reasonable attorneys' fees, which may be imposed upon, incurred by or
asserted against Landlord by reason of such default, and Tenant shall thereafter
promptly restore such letter of credit to its original amount. If Tenant fails
to restore such letter

                                      -32
<PAGE>

of credit to its original amount as hereinabove required, or if such letter of
credit is about to expire and shall not have been renewed as herein required
within thirty (30) days preceding such expiration, then in any such event
Landlord may upon demand withdraw all remaining available funds under such
letter of credit and hold the same as a cash security deposit pursuant to the
preceding provisions of this Section. So long as Tenant is not then in default
hereunder and has not prior thereto been given written notice of any such
default on more than two (2) occasions during any twelve (12) month period, the
Security Deposit may be reduced to $216,000 effective as of the first day of the
31st full calendar month included in the Term of this Lease.

     32.   Environmental Provisions. Tenant shall not bring or permit to be
           ------------------------
brought or kept in or on the Premises or elsewhere on the Property any hazardous
materials, as such terms may be defined by any applicable federal, state or
local statute, ordinance, by-law, rule or regulation, including without
limitation the Massachusetts Oil and Hazardous Material Release Prevention and
Response Act (M.G.L. c. 21E), the Comprehensive Environmental Response,
Compensation and Liability Act, as amended (42 U.S.C. (S)(S)9601 et seq.), and
the Resource Conservation and Recovery Act, as amended (42 U.S.C. (S)(S)6901 et
seq.), but excluding cleaning supplies and other products typically used by
tenants of office space, so long as such products are commercially packaged and
properly stored and handled. Landlord shall be responsible for the remediation,
if and as required by applicable law, of any such hazardous materials present on
the Property other than on account of Tenant's failure to comply with the
provisions of this Section.

     33.   General Provisions. (a) The various rights and remedies contained in
           ------------------
this Lease and reserved to each of the parties shall not be exclusive of any
other right or remedy of such party, but shall be construed as cumulative and
shall be in addition to every other remedy now or hereafter existing at law, in
equity, or by statute. No delay or omission of the right to exercise any power
by either party shall impair any such right or power, or shall be construed as a
waiver

                                     -33-
<PAGE>

of any default or as acquiescence in any default. One or more waivers of
any covenant, term or condition of this Lease by either party shall not be
construed by the other party as a waiver of a subsequent breach of the same
covenants, terms or conditions. The consent or approval of either party to or of
any act by the other party of a nature requiring consent or approval shall not
be deemed to waive or render unnecessary consent to or approval of any
subsequent similar act.

     (b)   Where the words "Landlord" and "Tenant" are used in this Lease, they
shall include Landlord and Tenant and shall apply to persons, both men and
women, associations, partnerships and corporations, and in reading this Lease
the necessary grammatical changes required to make the provisions hereof mean
and apply to them shall be made in the same manner as if written into the Lease.
(c) Tenant hereby declares that in entering into this Lease, Tenant relied
solely upon the statements contained in this Lease and fully understands that no
agents or representatives of Landlord have authority to in any manner change,
add to or detract from the terms of this Lease.

     (c)   Tenant hereby declares that in entering into this Lease, Tenant
relied solely upon the statements contained in this Lease and fully understands
that no agents or representatives of Landlord have authority to in any manner
change, add to or detract from the terms of this Lease.

     (d)   The invalidity of one or more of the provisions of this Lease shall
not affect the remaining portions of this Lease; and, if any one or more of the
provisions of this Lease should be declared invalid by final order, decree or
judgment of a court of competent jurisdiction, this Lease shall be construed as
if such invalid provisions had not been included in this Lease.

     (e)   If Tenant shall be two or more persons or entities, each such person
or entity shall be jointly and severally liable for the payment of all sums due
to Landlord from Tenant under this Lease and the performance of all of Tenant's
covenants, agreements, or obligations under this Lease.

     (f)   The submission of this Lease for examination or its negotiation or
the negotiation of the transaction described herein does not constitute a final
agreement to lease, and the execution of this Lease by Tenant does not
constitute a binding contract until such time as this

                                     -34-
<PAGE>

Lease has been approved by the First Mortgagee. Landlord shall use good faith
efforts to promptly obtain such consent.

     (g)   In the event this Lease is in full force and effect without default
by Tenant, Landlord shall use reasonable efforts to notify Tenant of any space
in the Building which Landlord wishes to lease other than to the current tenant
or occupant thereof (if any). In no event shall the foregoing provisions be
construed as an option, right of first refusal or other entitlement to lease
such space, nor shall Landlord be obligated to make any concession to Tenant in
order to facilitate such leasing.

     (h)   In no event shall either party be liable to the other for indirect or
consequential damages.

     Executed as a sealed instrument as of the date first above written by the
duly authorized representatives of Landlord and Tenant.

EAST STREET ASSOCIATES                      ZEFER CORP.

By /s/ [ILLEGIBLE]                          By /s/ William A. Seibel
   ----------------------------                -------------------------------

Its General Partner                         Its President
    ---------------------------                 -----------------------------
      title (duly-authorized)                      title (duly-authorized)

                                     -35-
<PAGE>

                                   EXHIBIT A

                               Plan of Premises

                           [FLOOR PLAN APPEARS HERE]

<PAGE>

                                   EXHIBIT B

                             RULES AND REGULATIONS

     1.   The sidewalks, entrances, passages, courts, elevators, vestibules,
stairways, corridors or halls of the Building shall not be obstructed or
encumbered or used for any purpose other than ingress and egress to and from the
premises demised to any tenant or occupant.

     2.   No awnings or other projections shall be attached to the outside walls
or windows of the Building without the prior written consent of Landlord. No
curtains, blinds, shades, or screens shall be attached or hung in, or used in
connection with, any window or door of the Premises demised to any tenant or
occupant, without the prior written consent of Landlord, such consent not to be
unreasonably withheld or delayed. Any such awnings, projections, curtains,
blinds, shades, screens, or other fixtures permitted by Landlord must be of a
quality type, design and color, and attached in a manner, approved by Landlord.

     3.   The sashes, sash doors, skylights, windows, and doors that reflect or
admit light and air into the halls, passageways or other public places in the
Building shall not be covered or obstructed, nor shall any bottles, parcels, or
other articles be placed an any window sills.

     4.   No show cases or other articles shall be put in front of or affixed to
any part of the exterior of the Building, nor placed in the halls, corridors,
vestibules or other parts of the Building.

     5.   The water and wash closets and other plumbing fixtures shall not be
used for any purposes other than those for which they were constructed, and no
sweepings, rubbish, rags, or other substances shall be thrown therein.

     6.   No tenant or occupant shall mark, paint, drill into, or in any way
deface any part of the Building or the premises demised to such tenant or
occupant. No boring, cutting or stringing of wires shall be permitted, except
with the prior written consent of the Landlord, and as Landlord may direct. No
tenant or occupant shall install any resilient tile or similar floor
<PAGE>

covering in the premises demised to such tenant or occupant except in manner
approved by Landlord.

     7.   No bicycles, vehicles or animals of any kind shall be brought into or
kept in or about the Premises. Bicycles may be stored in racks, if any,
furnished for such purpose by Landlord in a common area of the Building.

     8.   Without the prior written consent of Landlord, no space in the
Building shall be used for manufacturing, or for the sale of merchandise, goods,
or property of any kind at auction.

     9.   No tenant shall make, or permit to be made, any unseemly or disturbing
noises or disturb or interfere with other tenants or occupants of the Building
or neighboring buildings or premises whether by the use of any musical
instrument, radio, television set or other audio device, unmusical noise,
whistling, singing, or in any other way. Nothing shall be thrown out of any
doors or windows.

     10.  Each tenant must, upon the termination of its tenancy, restore to
Landlord all keys of stores, offices and toilet rooms, either furnished to, or
otherwise procured by such tenant.

     11.  No tenant shall use or occupy, or permit any portion of the premises
demised to such tenant to be used or occupied, as an office for a public
stenographer or typist, or to a barber or manicure shop, or as an employment
bureau. No tenant or occupant shall engage or pay any employees in the Building,
except these actually working for such tenant or occupant in the Building, nor
advertise for laborers giving an address at the Building.

     12.  No tenant or occupant shall purchase spring water, ice, food,
beverage, lighting maintenance, cleaning towels, or other like service, from any
company or person not approved by Landlord, such approval not to be unreasonably
withheld.

     13.  Landlord shall have the right to prohibit any advertising by any
tenant or occupant which, in Landlord's opinion, tends to impair the reputation
of the Buildings or its desirability as

                                      -2-
<PAGE>

a building for offices, and upon notice from Landlord, such tenant occupant
shall refrain from or discontinue such advertising.

     14.  Landlord reserves the right to exclude from the Building, between the
hours after 6:00 p.m. and before 7:00 a.m. on Business Days (and from 1:00 p.m.
on Saturdays) and all hours on all other days, all persons who do not present a
pass to the Building signed by the Landlord. Landlord will furnish passes to
persons for whom any tenant requests such passes. Each tenant shall be
responsible for all persons for whom it requests such passes and shall be liable
to Landlord for all wrongful acts of such persons.

     15.  Each tenant, before closing and leaving the premises demised to such
tenant at any time, shall see that all entrance doors are locked and windows
closed.

     16.  Each tenant shall, at its expenses, provide artificial light in the
premises demised to such tenant for Landlord's agents, contractors, and
employees while performing janitorial or other cleaning services and making
repairs or alterations in said premises.

     17.  No premises shall be used, or permitted to be used, for lodging or
sleeping, or for any immoral or illegal purposes.

     18.  There shall not be used in the Building, either by any tenant or
occupant or by their agents or contractors, in the delivery or receipt of
merchandise, freight or other matter, any hand trucks or other means of
conveyance except those equipped with rubber tires, rubber side guards and such
other safeguards as Landlord may require.

     19.  Canvassing, soliciting and peddling in the Building are prohibited and
each tenant and occupant shall cooperate in seeking their prevention.

     20.  No tenant shall move, or permit to be moved, into or out of the
Building or the premises demised to such tenant, any heavy or bulky matter,
without the specific approval of Landlord. If any such matter requires special
handling, only a person holding a Master Rigger's

                                      -3-
<PAGE>

license shall be employed to perform such special handling. No tenant shall
place, or permit to be placed, on any part of the floor or floors of the
premises demised to such tenant, a load exceeding the floor load per square foot
which such floor was designed to carry and which is allowed by law. Landlord
reserves the right to prescribe the weight and position of safes and other heavy
matter, which must be placed so as to distribute the weight.

     21.  The requirements of tenants will be attended to only upon application
at the office of the managing agent of the Building. Building employees shall
not be required to perform, and shall not be requested by any tenant or occupant
to perform any work outside of their regular duties, unless under specific
instructions from the office of the managing agent of the Building.

     22.  Locks to premises shall not be changed or added without permission of
Landlord.

     23.  Landlord shall have the right to make such further rules and
regulations as it deems reasonably necessary.

                                      -4-
<PAGE>

                                   EXHIBIT C

                              711 ATLANTIC AVENUE

                            CLEANING SPECIFICATIONS

Please note:  All trash to be transported by trash cart.

              Trash bags are not to be left on floor landings.

Lobby and Public Areas
----------------------

     Daily
     -----

1.   Pull all trash and replace liners as necessary.

2.   Empty and wash all ashtrays.

3.   Remove dust from all furniture, window ledges, radiators, coat racks,
     artificial plants, paintings and other wall decorations using chemically
     treated clothes.

4.   Spot wash all woodwork, doors and wall around door frames and light
     switches.

5.   Vacuum or wipe clean all fabric upholstered furniture.

6.   Wash all glass top tables.

7.   Wipe down all telephone equipment.

8.   Spot clean all glass.

9.   Completely clean and polish all hardware.

10.  Thoroughly vacuum all carpet including edges.

11.  Completely sweep and wash all brick.

12.  Clean all elevator tracks, doors, walls, etc,

13.  Completely clean and polish all hardware.

14.  Spot clean all carpeting.

     Weekly
     ------

1.   Completely wash and polish all wood furniture.

2.   Dust and clean all baseboards.

3.   Completely wash all glass.

<PAGE>

General Office Areas
--------------------

     Daily
     -----

1.   Empty all trash receptacles and remove collected waste to dumpster. Replace
     plastic liners as needed.

2.   Dust and spot clean all horizontal surfaces of counter tops, fixtures,
     desks, chairs, tables, offices equipment, window sills and blinds,
     radiators, partitions, and filing equipment.

3.   Damp wipe all telephones.

4.   Vacuum clean all traffic lanes and obviously soiled carpeted surfaces.

5.   Vacuum clean all exposed carpeted floor surfaces, including edges, corners,
     and under easily moved furniture. Inspect carpet for spots and stains, and
     remove where possible.

6.   Spot clean all interior partition (sidelight) glass, including all office
     visual glass panels, all modular furniture Plexiglas panels and entry door
     window glass.

     Weekly
     ------

1.   Spot clean walls, doors, doorframes, kick and push plates, handles, light
     switches, fire hoses and extinguisher cabinets, and any other obviously
     soiled surfaces.

2.   Dust all pictures, charts and similar wall hangings.

3.   Dust mop hard floor surfaces and damp mop any spills or stains.

4.   Damp mop and spray buff all hard floor surfaced flooring.

     Semi - Annually
     ---------------

1.   Dust and damp wash all ceiling diffusers, grills and surrounding walls and
     ceiling.

                                      -2-

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