Document:

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                                                                    Exhibit 10.6
                                                                    ------------

         FORM OF FIRST AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT
         ------------------------------------------------------------

     This First Amended and Restated Investor Rights Agreement, dated as of
September 22, 2000, is entered into by and among Convergent Networks, Inc., a
Delaware corporation (the "Company"), Bing Yang, Hwang-Ruey Wang and John C.
Thibault (individually, a "Management Stockholder" and, collectively, the
"Management Stockholders"), the individuals and entities listed on Attachment A
                                                                   ------------
hereto (the "Existing Investors"), and the individuals and entities listed on
Attachment B hereto (the "New Investors" and, collectively with the Existing
------------
Investors, the "Investors").

                                  BACKGROUND
                                  ----------

     WHEREAS, the Company, the Management Stockholders and certain of the
Existing Investors are parties to an Investor Rights Agreement dated as of July
14, 1998 (the "Original Agreement");

     WHEREAS, the Original Agreement has been amended on February 10, 1999, July
1, 1999, December 17, 1999, February 15, 2000 and March 31, 2000;

     WHEREAS, the Original Agreement, as amended to date, may only be amended by
a written instrument signed by the Company and stockholders holding at least 67%
of the Registrable Shares (as defined below) held by all Stockholders (as
defined below);

     WHEREAS, the undersigned hold at least 67% of the Registrable Shares held
by all Stockholders;

     WHEREAS, the Company, certain of the Existing Investors and the New
Investors have entered into a Series D Preferred Stock Purchase Agreement of
even date herewith (the "Purchase Agreement"); and

     WHEREAS, the Company, the Management Stockholders and the Investors wish to
amend and restate the Original Agreement in the manner set forth below;

     NOW, THEREFORE, in consideration of the mutual promises and covenants
contained in this Agreement, and the consummation of the sale and purchase of
the Series D Preferred Stock pursuant to the Purchase Agreement, and for other
valuable consideration, receipt of which is hereby acknowledged, the parties
hereto agree as follows:

ARTICLE I.    DEFINITIONS

     1.  Certain Definitions. As used in this Agreement, the following terms
         -------------------
shall have the following respective meanings:

         "Commission" means the United States Securities and Exchange
          ----------
Commission, or any other federal agency at the time administering the Securities
Act.

         "Common Stock" means the Common Stock, $0.00001 par value, of the
          ------------
Company.
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          "Exchange Act" means the Securities Exchange Act of 1934, as amended,
           ------------
or any similar federal statute, and the rules and regulations of the Commission
issued under such Act, as they each may, from time to time, be in effect.

          "Initial Public Offering" means the initial public offering of shares
           -----------------------
of Common Stock pursuant to a Registration Statement at a price to the public of
at least $20.44 per share (adjusted for stock splits, stock dividends and
similar events) resulting in gross proceeds to the Company and any selling
stockholders of at least $50,000,000.

          "Management Stockholders" means the Management Stockholders and any
           -----------------------
persons or entities to whom the rights granted and obligations assumed under
this Agreement are transferred by the Management Stockholders, their successors
or assigns pursuant to Section 2 of Article V.

          "Registration Statement" means a registration statement filed by the
           ----------------------
Company with the Commission for a public offering and sale of Common Stock
(other than a registration statement on Form S-8 or Form S-4, or their
successors, or any other form for a similar limited purpose, or any registration
statement covering only securities proposed to be issued in exchange for
securities or assets of another corporation).

          "Registration Expenses" means the expenses described in Section 4 of
           ---------------------
Article III.

          "Registrable Shares" means (i) the shares of Common Stock issued or
           ------------------
issuable upon conversion of the Shares, (ii) with respect to Section 2 of
Article III, shares of Common Stock held by the Management Stockholders, (iii)
any shares of Common Stock, and any shares of Common Stock issued or issuable
upon the conversion or exercise of any other securities, acquired by the
Investors pursuant to Article IV of this Agreement, and (iv) any other shares of
Common Stock issued in respect of such shares (because of stock splits, stock
dividends, reclassifications, recapitalizations or similar events); provided,
                                                                    --------
however, that shares of Common Stock which are Registrable Shares shall cease to
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be Registrable Shares (a) upon any sale pursuant to a Registration Statement or
Rule 144 under the Securities Act, (b) upon any sale in any manner to a person
or entity which, by virtue of Section 2 of Article V, is not entitled to the
rights provided by this Agreement, or (c) at such time as such shares are
eligible for resale pursuant to Rule 144(k) under the Securities Act.  Wherever
reference is made in this Agreement to a request or consent of holders of a
certain percentage of Registrable Shares, the determination of such percentage
shall include shares of Common Stock issuable upon conversion of the Shares even
if such conversion has not yet been effected.

          "Securities Act" means the Securities Act of 1933, as amended, or any
           --------------
similar federal statute, and the rules and regulations of the Commission issued
under such Act, as they each may, from time to time, be in effect.

          "Shares" means (i) the shares of Series A Preferred Stock, $0.01 par
           ------
value per share, of the Company, (ii) the shares of Series B Preferred Stock,
$0.01 par value per share, of the Company, (iii) the shares of Series C
Preferred Stock, $0.01 par value per share, of the Company, and the shares of
Series D Preferred Stock, $0.01 par value per share, of the Company.

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          "Stockholders" means the Investors and any persons or entities to whom
           ------------
the rights granted under this Agreement are transferred by the Investors, their
successors or assigns pursuant to Section 2 of Article V.

ARTICLE II.    VOTING RIGHTS

     1.   Voting of Shares. In any and all elections of directors of the Company
          ----------------
(whether at a meeting or by written consent in lieu of a meeting), each Investor
and Management Stockholder shall vote or cause to be voted all Voting Shares (as
defined in Section 2 of Article II) owned by him or it, or over which he or it
has voting control, and otherwise use his or its respective best efforts, so as
to fix the number of directors at six and to elect as directors (i) one
representative designated by the holders of a majority of the then outstanding
shares of Common Stock, (ii) the Chief Executive Officer of the Company, (iii)
one representative designated by Battery Ventures IV, L.P., (iv) one
representative designated by Matrix Partners V, L.P., and (v) two
representatives whom is neither a stockholder, director, officer or employee of
the Company, to be agreed upon by the directors designated pursuant to clauses
(ii), (iii) and (iv) above, one of whom is currently William Foster.

     2.   Voting Shares. "Voting Shares" shall mean and include any and all
          -------------
shares of the Common Stock, Series A Preferred Stock, Series B Preferred Stock,
Series C Preferred Stock, Series D Preferred Stock and/or shares of capital
stock of the Company, by whatever name called, which carry voting rights
(including voting rights which arise by reason of default) which are now owned
or subsequently acquired by an Investor or Management Stockholder, however
acquired, including without limitation stock splits and stock dividends.

     3.   Restrictive Legend. All certificates representing Voting Shares owned
          ------------------
or hereafter acquired by the Investors and Management Stockholders or any
transferee bound by this Agreement shall have affixed thereto a legend
substantially in the following form:

          "The shares of stock represented by this certificate are
          subject to certain voting agreements as set forth in the
          First Amended and Restated Investor Rights Agreement by and
          among the registered owner of this certificate, the Company
          and certain other stockholders of the Company, a copy of
          which is available for inspection at the offices of the
          Secretary of the Company."

     4.  Transfers of Voting Rights.  Any transferee to whom Voting Shares are
         --------------------------
transferred by an Investor or Management Stockholder, whether voluntarily or by
operation of law, shall be bound by the voting obligations imposed upon the
transferor under this Agreement, and shall be entitled to the rights granted to
the transferor under this Agreement, to the same extent as if such transferee
were an Investor or Management Stockholder hereunder.

ARTICLE III.    REGISTRATION RIGHTS

     1.   Required Registrations.
          ----------------------

          (a)  At any time beginning 180 days after the closing of the Company's
first underwritten public offering of shares of Common Stock pursuant to a
Registration Statement, a

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Stockholder or Stockholders holding in the aggregate at least 35% of the
Registrable Shares may request, in writing, that the Company effect the
registration on Form S-1 or Form S-2 (or any successor form) of Registrable
Shares owned by such Stockholder having an aggregate offering price of at least
$5,000,000 (based on the then current market price). If the Stockholder or
Stockholders initiating the registration intend(s) to distribute the Registrable
Shares by means of an underwriting, such Stockholder or Stockholders shall so
advise the Company in its request. In the event such registration is
underwritten, the right of other Stockholders to participate in such
registration shall be conditioned on such Stockholders' participation in such
underwriting. Upon receipt of any such request, the Company shall promptly give
written notice of such proposed registration to all other Stockholders. Such
Stockholders shall have the right, by giving written notice to the Company
within 30 days after the Company provides its notice, to elect to have included
in such registration such of their Registrable Shares as such Stockholders may
request in such notice of election; provided that if the underwriter (if any)
managing the offering determines that, because of marketing factors, all of the
Registrable Shares requested to be registered by all Stockholders may not be
included in the offering, then all Stockholders who have requested registration
shall participate in the registration pro rata based upon the number of
Registrable Shares which they have requested to be so registered. Thereupon, the
Company shall, as expeditiously as possible, use its reasonable best efforts to
effect the registration on Form S-1 or Form S-2 (or any successor form) of all
Registrable Shares which the Company has been requested to so register.

          (b)  At any time after the Company becomes eligible to file a
Registration Statement on Form S-3 (or any successor form relating to secondary
offerings), a Stockholder or Stockholders may request the Company, in writing,
to effect the registration on Form S-3 (or such successor form), of Registrable
Shares having an aggregate offering price of at least $1,000,000 (based on the
then current public market price). Upon receipt of any such request, the Company
shall promptly give written notice of such proposed registration to all other
Stockholders. Such Stockholders shall have the right, by giving written notice
to the Company within 30 days after the Company provides its notice, to elect to
have included in such registration such of their Registrable Shares as such
Stockholders may request in such notice of election; provided that if the
underwriter (if any) managing the offering determines that, because of marketing
factors, all of the Registrable Shares requested to be registered by all
Stockholders may not be included in the offering, then all Stockholders who have
requested registration shall participate in the registration pro rata based upon
the number of Registrable Shares which they have requested to be so registered.
Thereupon, the Company shall, as expeditiously as possible, use its reasonable
best efforts to effect the registration on Form S-3 (or such successor form) of
all Registrable Shares which the Company has been requested to so register.

          (c)  The Company shall not be required to effect more than two
registrations pursuant to paragraph (a) above; provided, however, that such
                                               --------  -------
obligation shall be deemed satisfied only when a registration statement covering
the applicable Registrable Shares shall have (i) become effective and, if such
method of disposition is a firm commitment underwritten public offering, all
such Registrable Shares have been sold pursuant thereto, or (ii) been withdrawn
at the request of the Stockholders requesting such registration (other than as a
result of information concerning the business or financial condition of the
Company which is made known to the Stockholders after the date on which such
registration was requested). There shall be no limit on the number of
registrations which may be requested pursuant to paragraph (b) above. In
addition,

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the Company shall not be required to effect any registration (other than on Form
S-3 or any successor form relating to secondary offerings) within six months
after the effective date of any other Registration Statement on Form S-1 of the
Company.

          (d)  If at the time of any request to register Registrable Shares
pursuant to this Section 1, the Company is engaged or has plans to engage within
90 days of the time of the request in a registered public offering of securities
for its own account or is engaged in any other activity which, in the good faith
determination of the Company's Board of Directors, would be adversely affected
by the requested registration to the material detriment of the Company, then the
Company may at its option direct that such request be delayed for a period not
in excess of six months from the effective date of such offering or the date of
commencement of such other material activity, as the case may be, such right to
delay a request to be exercised by the Company not more than once in any 12-
month period.

     2.   Incidental Registration.
          -----------------------

          (a)  Whenever the Company proposes to file a Registration Statement at
any time and from time to time, whether at the request of any Stockholder or
otherwise (other than a Registration Statement filed in connection with the
Company's initial public offering of Common Stock), it will, prior to such
filing, give written notice to all Stockholders and all Management Stockholders
of its intention to do so and, upon the written request of a Stockholder or
Stockholders, or a Management Stockholder or Management Stockholders, given
within 30 days after the Company provides such notice (which request shall state
the intended method of disposition of such Registrable Shares), the Company
shall use its reasonable best efforts to cause all Registrable Shares which the
Company has been requested by such Stockholder or Stockholders, or Management
Stockholder or Management Stockholders, to register to be registered under the
Securities Act to the extent necessary to permit their sale or other disposition
in accordance with the intended methods of distribution specified in the request
of such Stockholder or Stockholders, or Management Stockholder or Management
Stockholders; provided, however, that the Company shall have the right to
              --------  -------
postpone or withdraw any registration effected pursuant to this Section 2
without obligation to any Stockholder or Management Stockholder.

     (b)  In connection with any registration under this Section 2 involving an
underwriting, the Company shall not be required to include any Registrable
Shares in such registration unless the holders thereof accept the terms of the
underwriting as agreed upon between the Company and the underwriters selected by
it. If in the opinion of the managing underwriter it is desirable because of
marketing factors to limit the number of Registrable Shares to be included in
the offering, then the Company shall be required to include in the registration
only that number of Registrable Shares, if any, which the managing underwriter
believes should be included therein; provided, however, that no persons or
                                     --------  -------
entities other than the Company, the Stockholders, the Management Stockholders
and other persons or entities holding registration rights shall be permitted to
include securities in the offering. If the number of Registrable Shares to be
included in the offering in accordance with the foregoing is less than the total
number of shares which the holders of Registrable Shares have requested to be
included, then the holders of Registrable Shares who have requested registration
and other holders of securities entitled to include them in such registration
shall participate in the registration pro rata based upon their

                                      -5-
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total ownership of shares of Common Stock (giving effect to the conversion into
Common Stock of all securities convertible thereinto); provided, however, that
                                                       --------  -------
if the Registration Statement is filed by the Company upon the exercise of
demand registration rights held by stockholders other than holders of
Registrable Shares ("Other Holders") and does not include shares to be sold for
the account of the Company, then the Other Holders shall be entitled to include
all of the shares requested by them to be included in such Registration
Statement before holders of Registrable Shares shall be entitled to include
Registrable Shares therein. If any holder would thus be entitled to include more
securities than such holder requested to be registered, the excess shall be
allocated among other requesting holders pro rata in the manner described in the
preceding sentence.

     3.  Registration Procedures. If and whenever the Company is required by the
         -----------------------
provisions of this Agreement to use its reasonable best efforts to effect the
registration of any of the Registrable Shares under the Securities Act, the
Company shall:

         (a)  File with the Commission a Registration Statement with respect to
such Registrable Shares and use its reasonable best efforts to cause that
Registration Statement to become and remain effective;

         (b)  As expeditiously as possible prepare and file with the Commission
any amendments and supplements to the Registration Statement and the prospectus
included in the Registration Statement as may be necessary to keep the
Registration Statement effective, in the case of a firm commitment underwritten
public offering, until each underwriter has completed the distribution of all
securities purchased by it, and, in the case of any other offering, until the
earlier of the sale of all Registrable Shares covered thereby or 120 days after
the effective date thereof;

         (c)  As expeditiously as possible furnish to each selling Stockholder
or Management Stockholder such reasonable numbers of copies of the prospectus,
including a preliminary prospectus, in conformity with the requirements of the
Securities Act, and such other documents as the selling Stockholder or
Management Stockholder may reasonably request in order to facilitate the public
sale or other disposition of the Registrable Shares owned by the selling
Stockholder or Management Stockholder; and

         (d)  As expeditiously as possible use its best efforts to register or
qualify the Registrable Shares covered by the Registration Statement under the
securities or Blue Sky laws of such states as the selling Stockholder or
Management Stockholder shall reasonably request, and do any and all other acts
and things that may be necessary or desirable to enable the selling Stockholder
or Management Stockholder to consummate the public sale or other disposition in
such states of the Registrable Shares owned by the selling Stockholder or
Management Stockholder; provided, however, that the Company shall not be
                        --------  -------
required in connection with this paragraph (d) to qualify as a foreign
corporation or execute a general consent to service of process in any
jurisdiction.

         (e)  Use its best efforts to have the Registrable Shares listed,
subject to notice, on the NASDAQ National Market or other applicable exchange.

                                      -6-
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     If the Company has delivered preliminary or final prospectuses to the
selling Stockholders or Management Stockholders and after having done so the
prospectus is amended to comply with the requirements of the Securities Act, the
Company shall promptly notify the selling Stockholders or Management
Stockholders and, if requested, the selling Stockholders or Management
Stockholders shall immediately cease making offers of Registrable Shares and
return all prospectuses to the Company.  The Company shall promptly provide each
selling Stockholder and Management Stockholder with revised prospectuses and,
following receipt of the revised prospectuses, the selling Stockholder or
Management Stockholder shall be free to resume making offers of the Registrable
Shares.

     Notwithstanding the foregoing, each selling Stockholder and Management
Stockholder shall cease making offers or sales pursuant to a Registration
Statement during any period (not to exceed 90 days in any 12-month period) in
which the Company determines, by notice to each selling Stockholder and
Management Stockholder, that it is in possession of material non-public
information.

     4.  Allocation of Expenses. The Company will pay all Registration Expenses
         ----------------------
of all registrations under this Agreement; provided, however, that if a
                                           --------  -------
registration under Section 1 of Article III is withdrawn at the request of the
Stockholders requesting such registration (other than as a result of information
concerning the business or financial condition of the Company which is made
known to the Stockholders after the date on which such registration was
requested) and if the requesting Stockholders elect not to have such
registration counted as a registration requested under Article III, Section 1,
the requesting Stockholders shall pay the Registration Expenses of such
registration pro rata in accordance with the number of their Registrable Shares
included in such registration. For purposes of this Section 4, the term
"Registration Expenses" shall mean all expenses incurred by the Company in
complying with Article III, Section 1, including, without limitation, all
registration and filing fees, exchange listing fees, printing expenses, fees and
expenses of counsel for the Company and the fees and expenses of one counsel
selected by the selling Stockholder(s) to represent the selling Stockholder(s),
state Blue Sky fees and expenses, and the expense of any special audits incident
to or required by any such registration, but excluding underwriting discounts,
selling commissions and the fees and expenses of selling Stockholders' and
Management Stockholders' own counsel (other than the counsel selected to
represent all selling Stockholder(s)).

     5.  Indemnification and Contribution.
         --------------------------------

         (a)  In the event of any registration of any of the Registrable Shares
under the Securities Act pursuant to this Agreement, the Company will indemnify
and hold harmless the seller of such Registrable Shares, each underwriter of
such Registrable Shares, and each other person, if any, who controls such seller
or underwriter within the meaning of the Securities Act or the Exchange Act
against any losses, claims, damages or liabilities, joint or several, to which
such seller, underwriter or controlling person may become subject under the
Securities Act, the Exchange Act, state securities or Blue Sky laws or
otherwise, insofar as such losses, claims, damages or liabilities (or actions in
respect thereof) arise out of or are based upon any untrue statement or alleged
untrue statement of any material fact contained in any Registration Statement
under which such Registrable Shares were registered under the Securities Act,
any preliminary prospectus or final prospectus contained in the Registration
Statement, or any

                                      -7-
<PAGE>

amendment or supplement to such Registration Statement, or arise out of or are
based upon the omission or alleged omission to state a material fact required to
be stated therein or necessary to make the statements therein not misleading;
and the Company will reimburse such seller, underwriter and each such
controlling person for any legal or any other expenses reasonably incurred by
such seller, underwriter or controlling person in connection with investigating
or defending any such loss, claim, damage, liability or action; provided,
                                                                --------
however, that the Company will not be liable in any such case to the extent that
-------
any such loss, claim, damage or liability arises out of or is based upon any
untrue statement or omission made in such Registration Statement, preliminary
prospectus or final prospectus, or any such amendment or supplement, in reliance
upon and in conformity with information furnished to the Company, in writing, by
or on behalf of such seller, underwriter or controlling person specifically for
use in the preparation thereof.

         (b)  In the event of any registration of any of the Registrable Shares
under the Securities Act pursuant to this Agreement, each seller of Registrable
Shares, severally and not jointly, will indemnify and hold harmless the Company,
each of its directors and officers and each underwriter (if any) and each
person, if any, who controls the Company or any such underwriter within the
meaning of the Securities Act or the Exchange Act, against any losses, claims,
damages or liabilities, joint or several, to which the Company, such directors
and officers, underwriter or controlling person may become subject under the
Securities Act, Exchange Act, state securities or Blue Sky laws or otherwise,
insofar as such losses, claims, damages or liabilities (or actions in respect
thereof) arise out of or are based upon any untrue statement or alleged untrue
statement of a material fact contained in any Registration Statement under which
such Registrable Shares were registered under the Securities Act, any
preliminary prospectus or final prospectus contained in the Registration
Statement, or any amendment or supplement to the Registration Statement, or
arise out of or are based upon any omission or alleged omission to state a
material fact required to be stated therein or necessary to make the statements
therein not misleading, if the statement or omission was made in reliance upon
and in conformity with information relating to such seller furnished in writing
to the Company by or on behalf of such seller specifically for use in connection
with the preparation of such Registration Statement, prospectus, amendment or
supplement; provided, however, that the obligations of such Stockholders
            --------  -------
hereunder shall be limited to an amount equal to the proceeds to each
Stockholder of Registrable Shares sold in connection with such registration.

         (c)  Each party entitled to indemnification under this Article III,
Section 5 (the "Indemnified Party") shall give notice to the party required to
provide indemnification (the "Indemnifying Party") promptly after such
Indemnified Party has actual knowledge of any claim as to which indemnity may be
sought, and shall permit the Indemnifying Party to assume the defense of any
such claim or any litigation resulting therefrom; provided, that counsel for the
                                                  --------
Indemnifying Party, who shall conduct the defense of such claim or litigation,
shall be approved by the Indemnified Party (whose approval shall not be
unreasonably withheld); and, provided, further, that the failure of any
                             --------  -------
Indemnified Party to give notice as provided herein shall not relieve the
Indemnifying Party of its obligations under this Article III, Section 5. The
Indemnified Party may participate in such defense at such party's expense;
provided however that the Indemnifying Party shall pay such expense if
representation of such Indemnified Party by the counsel retained by the
Indemnifying Party would be inappropriate due to actual or potential differing
interests between the Indemnified Party and any other party represented by

                                      -8-
<PAGE>

such counsel in such proceeding. No Indemnifying Party, in the defense of any
such claim or litigation shall, except with the consent of each Indemnified
Party, consent to entry of any judgment or enter into any settlement which does
not include as an unconditional term thereof the giving by the claimant or
plaintiff to such Indemnified Party of a release from all liability in respect
of such claim or litigation, and no Indemnified Party shall consent to entry of
any judgment or settle such claim or litigation without the prior written
consent of the Indemnifying Party.

         (d)  In order to provide for just and equitable contribution to joint
liability under the Securities Act in any case in which either (i) any holder of
Registrable Shares exercising rights under this Agreement, or any controlling
person of any such holder, makes a claim for indemnification pursuant to this
Article III, Section 5 but it is judicially determined (by the entry of a final
judgment or decree by a court of competent jurisdiction and the expiration of
time to appeal or the denial of the last right of appeal) that such
indemnification may not be enforced in such case notwithstanding the fact that
this Article III, Section 5 provides for indemnification in such case, or (ii)
contribution under the Securities Act may be required on the part of any such
selling Stockholder or any such controlling person in circumstances for which
indemnification is provided under this Article III, Section 5; then, in each
such case, the Company and such Stockholder will contribute to the aggregate
losses, claims, damages or liabilities to which they may be subject (after
contribution from others) in such proportions so that such holder is responsible
for the portion represented by the percentage that the public offering price of
its Registrable Shares offered by the Registration Statement bears to the public
offering price of all securities offered by such Registration Statement, and the
Company is responsible for the remaining portion; provided, however, that, in
                                                  --------  -------
any such case, (A) no such holder will be required to contribute any amount in
excess of the proceeds to it of all Registrable Shares sold by it pursuant to
such Registration Statement, and (B) no person or entity guilty of fraudulent
misrepresentation, within the meaning of Section 11(f) of the Securities Act,
shall be entitled to contribution from any person or entity who is not guilty of
such fraudulent misrepresentation.

     6.  Indemnification with Respect to Underwritten Offering. In the event
         -----------------------------------------------------
that Registrable Shares are sold pursuant to a Registration Statement in an
underwritten offering pursuant to Article III, Section 1, the Company agrees to
enter into an underwriting agreement containing customary representations and
warranties with respect to the business and operations of an issuer of the
securities being registered and customary covenants and agreements to be
performed by such issuer, including without limitation customary provisions with
respect to indemnification by the Company of the underwriters of such offering.

     7.  Information by Holder.  Each Stockholder and Management Stockholder
         ---------------------
including Registrable Shares in any registration shall furnish to the Company
such information regarding such Stockholder or Management Stockholder and the
distribution proposed by such Stockholder or Management Stockholder as the
Company may reasonably request in writing and as shall be required in connection
with any registration, qualification or compliance referred to in this
Agreement.

     8.  "Stand-Off" Agreement.  Except with respect to transfers permitted by
          --------------------
Section 7.2(2) of the Purchase Agreement where the transferee agrees in writing
to be subject to the

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<PAGE>

terms and conditions of any lock-up agreement to which the transferor is a party
relating to the securities of the Company being transferred, each Stockholder
and Management Stockholder, if requested by the Company and the managing
underwriter of an offering by the Company of Common Stock or other securities of
the Company pursuant to a Registration Statement, shall agree not to sell
publicly or otherwise transfer or dispose of any Registrable Shares or other
securities of the Company held by such Stockholder for a specified period of
time (not to exceed 180 days) following the effective date of such Registration
Statement; provided that:

         (a)  such agreement shall only apply to the first Registration
Statement covering Common Stock to be sold on its behalf to the public in an
underwritten offering;

         (b)  all officers and directors of the Company and all holders of at
least 5% of the Company's capital stock enter into similar agreements; and

         (c)  the Company and the managing underwriter shall agree not to
release (other than early releases granted to parties other than officers and
directors of the Company, in an aggregate amount not to exceed 100,000 shares of
Common Stock) any of the parties listed in subparagraph (b) above prior to the
grant of a proportional release to the Stockholders.

     9.  Limitations on Subsequent Registration Rights.  The Company shall not,
         ---------------------------------------------
without the prior written consent of Stockholders holding at least 67% of the
Registrable Shares held by all Stockholders, enter into any agreement (other
than this Agreement) with any holder or prospective holder of any securities of
the Company which would allow such holder or prospective holder to include
securities of the Company in any Registration Statement, unless under the terms
of such agreement, such holder or prospective holder may include such securities
in any such registration only on terms substantially similar to the terms on
which holders of Registrable Shares may include shares in such registration.

     10. Rule 144 Requirements. After the earliest of (a) the closing of the
         ---------------------
sale of securities of the Company pursuant to a Registration Statement, (b) the
registration by the Company of a class of securities under Section 12 of the
Exchange Act, or (c) the issuance by the Company of an offering circular
pursuant to Regulation A under the Securities Act, the Company agrees to:

         (i)   Comply with the requirements of Rule 144(c) under the Securities
Act with respect to current public information about the Company;

         (ii)  Use its best efforts to file with the Commission in a timely
manner all reports and other documents required of the Company under the
Securities Act and the Exchange Act (at any time after it has become subject to
such reporting requirements); and

         (iii) Furnish to any holder of Registrable Shares upon request (A) a
written statement by the Company as to its compliance with the requirements of
said Rule 144(c), and the reporting requirements of the Securities Act and the
Exchange Act (at any time after it has become subject to such reporting
requirements), (B) a copy of the most recent annual or quarterly report of the
Company, and (C) such other reports and documents of the Company as such holder
may reasonably request to avail itself of any similar rule or regulation of the
Commission allowing it to sell any such securities without registration.

                                      -10-
<PAGE>

ARTICLE IV.    RIGHT OF FIRST REFUSAL

     1.   Right of First Refusal
          ----------------------

          (a)  The Company shall not issue, sell or exchange, agree to issue,
sell or exchange, or reserve or set aside for issuance, sale or exchange, (i)
any shares of its Common Stock, (ii) any other equity securities of the Company,
including, without limitation, shares of preferred stock, (iii) any option,
warrant or other right to subscribe for, purchase or otherwise acquire any
equity securities of the Company, or (iv) any debt securities convertible into
capital stock of the Company (collectively, the "Offered Securities"), unless in
each such case the Company shall have first complied with Article IV of this
Agreement. The Company shall deliver to the Stockholders a written notice of any
proposed or intended issuance, sale or exchange of Offered Securities (the
"Offer"), which Offer shall (i) identify and describe the Offered Securities,
(ii) describe the price and other terms upon which they are to be issued, sold
or exchanged, and the number or amount of the Offered Securities to be issued,
sold or exchanged, (iii) identify the persons or entities, if known, to which or
with which the Offered Securities are to be offered, issued, sold or exchanged,
and (iv) offer to issue and sell to or exchange with each of the Stockholders
(A) such portion of the Offered Securities as the aggregate number of Shares
(including shares of Common Stock issuable upon conversion of the Shares even if
such conversion has not yet been effected) then held by such Stockholder bears
to the total number of shares of Common Stock then outstanding (including shares
of Common Stock issuable upon conversion of convertible securities even if such
conversion has not yet been effected) (the "Basic Amount"), and (B) such
additional portion of the Offered Securities as such Stockholder indicates it
will purchase or acquire should other Stockholders acquire less than all of the
Offered Securities initially offered to the other Stockholders (the
"Undersubscription Amount"). Each Stockholder shall have the right, for a period
of 30 days following delivery of the Offer, to purchase or acquire, at the price
and upon the other terms specified in the Offer, the number or amount of Offered
Securities described above. The Offer by its term shall remain open and
irrevocable for such 30-day period.

          (b)  To accept an Offer, in whole or in part, a Stockholder must
deliver a written notice to the Company prior to the end of the 30-day period of
the Offer, setting forth the portion of the Stockholder's Basic Amount that such
Stockholder elects to purchase and, if such Stockholder shall elect to purchase
all of its Basic Amount, the Undersubscription Amount (if any) that such
Stockholder elects to purchase (the "Notice of Acceptance"). If the Basic
Amounts subscribed for by all Stockholders are less than the total Offered
Securities, then each Stockholder who has set forth Undersubscription Amounts in
its Notice of Acceptance shall be entitled to purchase, in addition to the Basic
Amounts subscribed for, all Undersubscription Amounts it has subscribed for;
provided, however, that should the Undersubscription Amounts subscribed for
--------  -------
exceed the difference between the Offered Securities and the Basic Amounts
subscribed for (the "Available Undersubscription Amount"), each Stockholder who
has subscribed for any Undersubscription Amount shall be entitled to purchase
only that portion of the Available Undersubscription Amount as the
Undersubscription Amount subscribed for by such Stockholder bears to the total
Undersubscription Amounts subscribed for by all Stockholders, subject to
rounding by the Board of Directors to the extent it reasonably deems necessary.

                                      -11-
<PAGE>

          (c)  To the extent that Notices of Acceptance are not given by the
Stockholders in respect of all the Offered Securities, the Company shall have 90
days from the expiration of the period set forth in Article IV, Section 1(a) to
issue, sell or exchange all or any part of such Offered Securities as to which a
Notice of Acceptance has not been given by the Stockholders (the "Refused
Securities"), but only to the offerees or purchasers described in the Offer and
only upon terms and conditions (including, without limitation, unit prices and
interest rates) which are not more favorable, in the aggregate, to the acquiring
person or persons or less favorable to the Company than those set forth in the
Offer.

          (d)  In the event the Company shall propose to sell less than all the
Refused Securities (any such sale to be in the manner and on the terms specified
in Article IV, Section 1(c)), then each Stockholder may, at its sole option and
in its sole discretion, reduce the number or amount of the Offered Securities
specified in its Notice of Acceptance to an amount that shall be not less than
the number or amount of the Offered Securities that the Stockholder elected to
purchase pursuant to Article IV, Section 1(b) multiplied by a fraction, (i) the
numerator of which shall be the number or amount of Offered Securities the
Company actually proposes to issue, sell or exchange (including Offered
Securities to be issued or sold to Stockholders pursuant to Article IV, Section
1(b) prior to such reduction) and (ii) the denominator of which shall be the
amount of all Offered Securities. In the event that any Stockholder so elects to
reduce the number or amount of Offered Securities specified in its Notice of
Acceptance, the Company may not issue, sell or exchange more than the reduced
number or amount of the Offered Securities unless and until such securities have
again been offered to the Stockholders in accordance with Article IV, Section
1(a).

          (e)  Upon the closing of the issuance, sale or exchange of all or less
than all the Refused Securities, the Stockholders shall acquire from the
Company, and the Company shall issue to the Stockholders, the number or amount
of Offered Securities specified in the Notices of Acceptance, as reduced
pursuant to Article IV, Section 1(d) if the Stockholders have so elected, upon
the terms and conditions specified in the Offer. The purchase by the
Stockholders of any Offered Securities is subject in all cases to the
preparation, execution and delivery by the Company and the Stockholders of a
purchase agreement relating to such Offered Securities reasonably satisfactory
in form and substance to the Stockholders and their respective counsel.

          (f)  Any Offered Securities not acquired by the Stockholders or other
persons in accordance with Article IV, Section 1 may not be issued, sold or
exchanged until they are again offered to the Stockholders under the procedures
specified in this Article.

     2.   Excluded Issuances. The rights of the Stockholders under this Article
          ------------------
IV shall not apply to:

          (a)  Common Stock issued as a stock dividend to holders of Common
Stock or upon any subdivision or combination of shares of Common Stock;

          (b)  The issuance of the Shares and any shares of Common Stock issued
upon conversion thereof;

                                      -12-
<PAGE>

          (c)  Shares of Common Stock, or options exercisable therefor, issuable
to officers, directors, consultants and employees of the Company or any
subsidiary pursuant to any plan, agreement or arrangement approved by a vote of
the Board of Directors of the Company or the Compensation Committee of the Board
of Directors;

          (d)  Securities issued solely in consideration for the acquisition
(whether by merger or otherwise) by the Company or any of its subsidiaries of
all or substantially all of the stock or assets of any other entity;

          (e)  Shares of Common Stock sold by the Company in an underwritten
public offering pursuant to an effective registration statement under the
Securities Act; or

          (f)  Up to 1,000,000 shares of Common Stock issued by the Company,
with the approval of a majority of the Board of Directors, in connection with
lease financings, strategic alliances and similar arrangements.

ARTICLE V.    GENERAL

     1.   Termination.  Article II of this Agrement shall terminate on the
          -----------
 earlier of (a) the tenth anniversary of the date of this Agreement or (b) the
 closing of an Initial Public Offering. All of the Company's obligations to
 register Registrable Shares under Article III of this Agreement shall terminate
 on the tenth anniversary of the Initial Public Offering. Article IV of this
 Agreement shall terminate upon the earlier of (a) the sale of all or
 substantially all of the assets or business of the Company, by merger, sale of
 assets or otherwise, or (b) the closing of an Initial Public Offering.

     2.   Transfer of Rights. This Agreement, and the rights and obligations of
          ------------------
the Stockholders and Management Stockholders hereunder, may be assigned by the
Stockholders and Management Stockholders to any person or entity to which Shares
are transferred by the Stockholders or Management Stockholders, and such
transferee shall be deemed a "Stockholder" or "Management Stockholder" for
purposes of this Agreement; provided that (i) the transferee provides written
notice of such assignment to the Company and (ii) no assignee shall be a
customer or competitor of the Company unless the Board of Directors of the
Company otherwise agrees.

     3.   Severability. The provisions of this Agreement are severable, so that
          ------------
the invalidity or unenforceability of any provision of this Agreement shall not
affect the validity or enforceability of any other term or provision of this
Agreement, which shall remain in full force and effect.

     4.   Specific Performance. In addition to any and all other remedies that
          --------------------
may be available at law in the event of any breach of this Agreement, the
Stockholders shall be entitled to specific performance of the agreements and
obligations of the Company and the Stockholders hereunder and to such other
injunctive or other equitable relief as may be granted by a court of competent
jurisdiction.

                                      -13-
<PAGE>

     5.   Governing Law. This Agreement shall be governed by, and construed and
          -------------
enforced in accordance with, the laws of the State of Delaware (without
reference to the conflicts of law provisions thereof).

     6.   Notices. All notices, requests, consents, and other communications
          -------
under this Agreement shall be in writing and shall be delivered by hand or
mailed by first class certified or registered mail, return receipt requested,
postage prepaid:

     If to the Company, at Convergent Networks, Inc., 900 Chelmsford Street,
Tower 3, Lowell, Massachusetts 01851, Attention: President, or at such other
address or addresses as may have been furnished in writing by the Company to the
Purchasers, with a copy to Hale and Dorr LLP, 60 State Street, Boston,
Massachusetts 02109, Attention: John A. Burgess, Esq.;

     If to an Investor, at his or its address as set forth on Attachment A or
                                                              ------------
Attachment B, or at such other address or addresses as may have been furnished
------------
to the Company in writing by such Investor; or

     If to a Management Stockholder, at his address set forth below his
signature to this Agreement.

     Notices provided in accordance with this Article V, Section 6 shall be
deemed delivered upon personal delivery or two business days after deposit in
the mail.

     7.   Complete Agreement; Amendments. This Agreement constitutes the full
          ------------------------------
and complete agreement of the parties hereto with respect to the subject matter
hereof. This Agreement may be amended and any provision may be waived,
prospectively or retroactively, at any time by a written instrument signed by
the Company and Stockholders holding at least 67% of the Registrable Shares then
held by all Stockholders. No waivers of or exceptions to any term, condition or
provision of this Agreement, in any one or more instances, shall be deemed to
be, or construed as, a further or continuing waiver of any such term, condition
or provision.

     8.   Pronouns.  Whenever the content may require, any pronouns used in this
          --------
Agreement shall include the corresponding masculine, feminine or neuter forms,
and the singular form of nouns and pronouns shall include the plural, and vice
versa.

     9.   Counterparts. This Agreement may be executed in any number of
          ------------
counterparts, each of which shall be deemed to be an original, and all of which
together shall constitute one Agreement binding on all the parties hereto.

     10.  Captions. Captions of sections have been added only for convenience
          --------
and shall not be deemed to be a part of this Agreement.

     11.  Addition of Investors.  Each purchaser of shares of Series A Preferred
          ---------------------
Stock, Series B Preferred Stock, Series C Preferred Stock and Series D Preferred
Stock of the Company under the respective Stock Purchase Agreement shall become
a party to, and an "Investor" under, this Agreement upon the closing of its
purchase of its respective shares thereunder and its execution of a counterpart
signature page to this Agreement.

                                      -14-
<PAGE>

     12.  Cancellation of Original Agreement. This Agreement replaces the
          ----------------------------------
Original Agreement, as amended to date, in its entirety, and such Original
Agreement shall hereafter be null and void.

     13.  Aggregation of Stock. All shares of Series D Preferred Stock and
          --------------------
Common Stock held or acquired by affiliated entities or persons shall be
aggregated for the purpose of determining the availability of any rights under
this Agreement.

                                      -15-
<PAGE>

                                 Attachment A

                              Existing Investors
                              ------------------

Matrix Partners V, L.P.
1000 Winter Street
Waltham, MA 02451
Attn: David Schantz
Fax: 781-890-2288

Matrix V Entrepreneurs Fund L.P.
1000 Winter Street
Waltham, MA 02451
Attn: David Schantz
Fax: 781-890-2288

Battery Ventures IV, L.P.
20 William Street, Suite 200
Wellesley Office Park
Wellesley, MA 02481
Attn: Todd Dagres
Fax: 781-577-1001

Battery Investment Partners IV, L.L.C.
20 William Street, Suite 200
Wellesley Office Park
Wellesley, MA 02481
Attn: Todd Dagres
Fax: 781-577-1001

North Bridge Venture Partners II, L.P.
950 Winter Street
Suite 4600
Waltham, MA 02451
Attn: Ed Hamilton
Fax: 781-290-0999

Worldview Technology Partners III, L.P.
435 Tasso Street, Suite 120
Palo Alto, CA 94301
Attn: John Boyle
Fax: 650-322-3880

<PAGE>

Worldview Technology International III, L.P.
435 Tasso Street, Suite 120
Palo Alto, CA 94301
Attn: John Boyle
Fax: 650-322-3880

Worldview Strategic Partners III, L.P.
435 Tasso Street, Suite 120
Palo Alto, CA 94301
Attn: John Boyle
Fax: 650.322.3880

VantagePoint Communications Partners, L.P.
1001 Bayhill Drive
Suite 100
San Bruno, CA 94066

VantagePoint Venture Partners III (Q), L.P.
1001 Bayhill Drive
Suite 100
San Bruno, CA 94066

VantagePoint Venture Partner III, L.P.
1001 Bayhill Drive
Suite 100
San Bruno, CA 94066

B.A.B.P., L.L.C.
c/o GLOBAL NAPs, Inc.
10 Merrymount Road
Quincy, MA 02169
Attn: Frank Gangi
Tel: 617.507.5100
Fax: 617.507.5200

Anthony Medaglia
c/o Hutchins, Wheeler & Dittmar
101 Federal Street
Boston, MA 02110
Fax: 617.951.1295

Cheng Wu
303 Kimball Road
Carlisle, MA 01741

<PAGE>

Mahesh Ganmukhi
1286 Curve Street
Carlisle, MA 01742

Seamus Gilchrist
13 Tedington Way
Mt. Laurel, NJ 08054

Gregor Ferguson
153 Simon Willard Road
Concord, MA 01742

McQuillan Consulting Self/Employed Profit Sharing Retirement Plan
John M. McQuillan, Trustee
1620 Sudbury Road #4
Concord, MA 01742

Bing Yang
c/o Convergent Networks, Inc.
900 Chelmsford Street
Tower Three
Lowell, MA 01851

Hwang-Ruey Wang
c/o Convergent Networks, Inc.
900 Chelmsford Street
Tower Three
Lowell, MA 01851

Jennifer Pigg
c/o The Yankee Group
31 St. James Avenue
Boston, MA 02116

Yongdong Zhao
11108 Readville Lane
Austin, TX 78739

Karl May
281 Blue Ridge Road
North Andover, MA 01845

Cheng Wu
303 Kimball Road
Carlisle, MA 01741

<PAGE>

Jeffrey McCarthy
171 Pope Road
Acton, MA 01720

Dennis Rainville
50 Swanson Road
Carlisle, MA 01741

Pamela F. Lenehan
c/o Convergent Networks, Inc.
900 Chelmsford Street
Tower Three
Lowell, MA 01851

<PAGE>

                                 Attachment B

                                 New Investors
                                 -------------

PUTNAM OTC AND EMERGING GROWTH FUND
PUTNAM FUNDS TRUST-PUTNAM EQUITY FUND 2000
PUTNAM FUNDS TRUST-PUTNAM TECHNOLOGY FUND
c/o Putnam Investments
One Post Office Square
Boston, MA 02110
Attn: General Counsel

PUTNAM WORLD TRUST II-PUTNAM EMERGING INFORMATION
SCIENCES FUND
c/o Putnam Investments
One Post Office Square
Boston, MA 02110
Attn: General Counsel

Pilgrim Baxter Hybrid Partners I, L.P.
825 DuPortail Road
6 Wayne, PA 19087
Attn: Matthew DiClemente
Fax: 610-722-5840

Pilgrim Baxter Hybrid Partners II, L.P.
825 DuPortail Road
6 Wayne, PA 19087
Attn: Matthew DiClemente
Fax: 610-722-5840

Kemper Small Capitalization Equity Fund, Snorklebay & Co.
Chapman and Cutler
111 West Monroe Street
Chicago, IL 60603
Attn: Anthony D. Yager
Tel: 312-845-3731

Kemper Variable Series - Small Capitalization Growth Portfolio-
Snailsand & Co.
Chapman and Cutler
111 West Monroe Street
Chicago, IL 60603
Attn: Anthony D. Yager
Tel: 312-845-3731<PAGE>

                                                                  EXHIBIT 10.7
                                                                  ------------

                                     LEASE

                                    BETWEEN

                       CROSS POINT LIMITED PARTNERSHIP,
                                 as Landlord,

                                      AND

                          CONVERGENT NETWORKS, INC.,
                                   as Tenant

                          Dated as of August _, 1999

<PAGE>

                                  LEASE INDEX
                                  -----------

<TABLE>
     <S>                                                        <C>
     LEASE.....................................................   1
     SCHEDULE OF ESSENTIAL TERMS...............................   1
     SECTION 1.  DEMISE AND TERM...............................   3
     SECTION 2.  RENT..........................................   3
     SECTION 3.  USE...........................................   7
     SECTION 4.  CONSTRUCTION OF THE PREMISES..................   7
     SECTION 5.  UTILITIES AND OTHER SERVICES..................   8
     SECTION 6.  RULES AND REGULATIONS.........................  10
     SECTION 7.  CERTAIN RIGHTS RESERVED TO LANDLORD...........  10
     SECTION 8.  MAINTENANCE AND REPAIRS.......................  11
     SECTION 9.  ALTERATIONS...................................  11
     SECTION 10. INSURANCE.....................................  12
     SECTION 11. WAIVER AND INDEMNITY..........................  13
     SECTION 12. FIRE AND CASUALTY.............................  13
     SECTION 13. CONDEMNATION..................................  15
     SECTION 14. ASSIGNMENT AND SUBLETTING.....................  15
     SECTION 15. SURRENDER.....................................  17
     SECTION 16. DEFAULTS AND REMEDIES.........................  17
     SECTION 17. HOLDING OVER..................................  20
     SECTION 18. ESTOPPEL CERTIFICATES.........................  20
     SECTION 19. SUBORDINATION.................................  21
     SECTION 20. QUIET ENJOYMENT...............................  22
     SECTION 21. BROKER........................................  22
     SECTION 22. NOTICES.......................................  22
     SECTION 23. PARKING.......................................  22
     SECTION 24. COOPERATIVE INTERRUPTIBLE SERVICE AGREEMENT...  23
     SECTION 25. SECURITY DEPOSIT..............................  23
     SECTION 26. DIRECTORY; SIGNS..............................  23
     SECTION 27. RENEWAL OPTION................................  24
     SECTION 28. TELECOMMUNICATIONS EQUIPMENT..................  24
     SECTION 29. MISCELLANEOUS.................................  25
     EXHIBIT A - LEGAL DESCRIPTION OF FEE LAND.................   1
     EXHIBIT A-1 - LEGAL DESCRIPTION OF EASEMENT LAND..........   4
     EXHIBIT B - FLOOR PLAN OF PREMISES........................   1
     EXHIBIT C - SKETCH PLAN...................................   1
     EXHIBIT D - WORK LETTER...................................   2
     EXHIBIT E - LANDLORD'S SERVICES...........................   1
     EXHIBIT F - ..............................................   1
     RULES AND REGULATION S....................................   1
</TABLE>

                                       i
<PAGE>

                                     LEASE
                                     -----

     THIS LEASE is made as of the _______ day of August, 1999 by and between
CROSS POINT LIMITED PARTNERSHIP, a Massachusetts limited partnership having an
address at 900 Chelmsford Street, Lowell, Massachusetts 01851 ("Landlord"), and
Convergent Networks, Inc., a Delaware corporation having an address at 2
Highwood Drive, Tewksbury, MA 01876 ("Tenant"), for space in the Building (as
defined below).

     The following schedule (the "Schedule") sets forth certain basic terms of
this Lease:

                          SCHEDULE OF ESSENTIAL TERMS
                          ---------------------------

1.   Fee Land: The parcel of land known and numbered as 900 Chelmsford Street,
     --------
     Lowell, Massachusetts, located partly in Lowell and partly in Chelmsford,
     County of Middlesex, Commonwealth of Massachusetts, and more particularly
     described in Exhibit A attached hereto and incorporated herein by this
     reference.

2.   Easement Land: The parcel of land located in Lowell, County of Middlesex,
     -------------
     Commonwealth of Massachusetts, and more particularly described in Exhibit
     A-1 attached hereto and incorporated herein by this reference.

3.   Land:  Collectively, the Fee Land and the Easement Land.
     ----

4.   Building: The building, comprised of Towers I, II and III, located at the
     --------
     Fee Land and all other leasable improvements located at the Fee Land from
     time to time.

5.   Property:  Collectively, the Building, the Land and any other building or
     --------
     improvements hereafter located on or at the Fee Land.

6.   Premises: Approximately 72,632 rentable square feet of floor area (the
     --------
     "Premises Rentable Area") consisting of 36,316 rentable square feet on the
     eleventh (II') floor of Tower III of the Building and 36,316 rentable
     square feet of floor area on either the tenth (10') floor or the twelfth
     (12'h) floor of Tower III of the Building, to be delivered in accordance
     with Section 4 (a) hereof, as shown on the floor plans attached hereto as
     Exhibit B and incorporated herein by this reference.

7.   Commencement Date: September 13, 1999
     -----------------

8.   Expiration Date: September 12, 2006
     ---------------

9.   Annual Base Rent:   September 13, 1999-August 31, 2000: $17.00/RSF Gross
     ----------------
                         Plus Tenant electricity

                         September 1, 2000-August 31, 2001: $18-OO/RSF Gross
                         Plus Tenant electricity

                         September 1, 2001-August 31, 2002: $19.00/RSF Gross
                         Plus Tenant electricity

                         September 1, 2002-August 31, 2003: $20.00/RSF Gross
                         Plus Tenant electricity

                                      -1-
<PAGE>

                         September 1, 2003-August 31, 2004: $21.00/RSF Gross
                         Plus Tenant electricity

                         September 1, 2004-August 31, 2005: $22.00/RSF Gross
                         Plus Tenant electricity.

                         September 1, 2005-August 31, 2006: $23.00/RSF Gross
                         Plus Tenant electricity

                         September 1, 2006-September 12, 2006: $23.00/RSF Gross
                         Plus Tenant electricity

10.  Monthly Base Rent:  One twelfth (1/12th) of Annual Base Rent.
     -----------------

11.  Monthly Electricity Payment:  Such sum as is invoiced to Tenant
     ---------------------------
     pursuant to Section 5 hereof

12.  Tenant's Proportionate Share:  The quotient of the Premises Rentable
     ----------------------------
     Area divided by the total rentable floor area in the Building, as the same
     may be adjusted from time to time based on changes in Premises Rentable
     Area, the floor area of the Building, or both. As of the date of this
     Lease, the total rentable area of the Building is 1,216,738 square feet,
     and Tenant's Proportionate Share is 5.969%.

13.  Base Expense Year:  Calendar Year 1999 (i.e., January 1, 1999 -
     -----------------
     December 31, 1999).

14.  Base Tax Year:  Fiscal Year 2000 (i.e., July 1, 1999 - June 30, 2000).
     -------------

15.  Security Deposit:  Letter of Credit in the original amount of $500,000
     ----------------
     to be deposited with Landlord pursuant to Section 25 hereof.

16.  Broker(s):               Spaulding & Slye
     ---------
                              255 State Street
                              Boston, MA 02109
                              Attn: Curtis P. Oberg

                              Insignia/ESG, Inc.
                              One Financial Center
                              Boston, MA 02111
                              Attn: John Wilson

17.  Address of Landlord:     Cross Point Limited Partnership
     -------------------
                              900 Chelmsford Street
                              Lowell, Massachusetts 01851

18.  Address of Tenant:       Convergent Networks, Inc.
     -----------------
                              900 Chelmsford Street
                              Lowell, Massachusetts 01851

19.  Effective Date:   The date on which all of the following have occurred: (a)
     --------------
fall execution of this Lease, (b) delivery of the Security Deposit to Landlord,
and (c) payment of Base Rent for the first partial month and the first full
calendar month.

                                      -2-
<PAGE>

     1.   DEMISE AND TERM. Landlord hereby leases to Tenant and Tenant hereby
leases from Landlord the premises (the "Premises") described in Item 6 of the
Schedule, subject to the covenants and conditions set forth in this Lease, for a
term (the "Term") commencing on the date (the "Commencement Date") described in
Item 7 of the Schedule and expiring on the date (the "Expiration Date")
described in Item 8 of the Schedule, unless terminated earlier as otherwise
provided in this Lease. Upon the request of either of them, Landlord and Tenant
agree to execute a supplemental agreement confirming the configuration of the
Premises, once same has been determined.

Tenant shall have, as appurtenant to the Premises, the right to use in common
with others entitled thereto, subject to reasonable rules and regulations from
time to time made by Landlord: (a) the common lobbies, hallways, stairways and
elevators of the Building serving the Premises in common with others; (b) the
common walkways necessary for access to the Building; and (c) the common pipes,
ducts, conduits, wires and appurtenant fixtures serving the Premises.
Notwithstanding anything herein to the contrary, all the perimeter walls of the
Premises except the interior surfaces thereof, any space in or adjacent to the
Premises used for shafts, stacks, pipes, conduits, wires and appurtenant
fixtures, fan rooms, ducts, electric or other utilities, sinks or other Building
facilities, and the use thereof, are expressly excluded from the Premises and
reserved to Landlord.

     2.   RENT

     A.   Definitions.  For purposes of this Lease, the following
          -----------
          terms shall have the following meanings:

          (i)    "Base Expense Year" shall mean the year set forth in Item 13 of
                 Schedule.

          (ii)   "Base Tax Year" shall mean the year set forth in Item 14 of the
                 Schedule.

          (iii)  "Base Expenses" shall mean the amount of Expenses (as defined
                 below) for the Base Expense Year.

          (iv)   "Base Taxes" shall mean the amount of Taxes (as defined below)
                 for the Base Tax Year.

          (v)    "Expenses" shall mean all expenses, costs and disbursements
                 (other than Taxes) paid or incurred by Landlord in connection
                 with the ownership, management, maintenance, operation,
                 replacement and repair of the Property, including by way of
                 example rather than limitation: security expenses; legal fees;
                 salaries, wages, fringe benefits, worker's compensation
                 insurance premiums and payroll ' taxes and union dues of
                 workers and other on-site employees of Landlord; all insurance
                 premiums, fees and impositions; costs of capital improvements
                 made or installed for purposes of reducing Expenses or made or
                 installed pursuant to governmental requirements or insurance
                 requirements, and the replacement of equipment or improvements,
                 as amortized over their useful lives in accordance with
                 generally accepted accounting principles; costs for repairs,
                 maintenance, service contracts, management fees, governmental
                 permits and overhead expenses; costs of furnishing water,
                 sewer, gas, fuel, electricity and other utility services;
                 janitorial service, care of interior and exterior landscaping,
                 snow removal and trash removal; and the costs of any other
                 items attributable to operating or maintaining any or all of
                 the Property. Expenses shall not include: (a) costs of tenant
                 alterations; (b) interest and principal payments on mortgages
                 (except interest on the cost of any capital improvements for
                 which

                                      -3-
<PAGE>

                 amortization may be included in the definition of Expenses) or
                 any rental payments on any ground leases (except for rental
                 payments which constitute reimbursement for Taxes and
                 Expenses); (c) advertising expenses and leasing commissions;
                 (d) any cost or expenditure for which Landlord is reimbursed,
                 whether by insurance proceeds or otherwise, except through
                 Adjustment Rent (as defined below); (e) the cost of any kind of
                 service furnished to any other tenant in the Building which
                 Landlord does not generally make available to all tenants in
                 the Building; and (f) legal expenses of negotiating leases.

          (vi)   "Rent" shall mean Base Rent (as defined below), Adjustment Rent
                 (as defined below), and any other sums or charges due by Tenant
                 hereunder.

          (vii)  "Taxes" shall mean all taxes, assessments, betterments and fees
                 levied upon the Building, the Fee Land, the Easement Land (but
                 only to the extent that such taxes, assessments and fees are
                 paid or payable by Landlord to the taxing authority or are
                 reimbursed or reimbursable by Landlord to a third party which
                 has an interest in the Easement Land and which is obligated as
                 between Landlord and such third party to pay taxes, assessments
                 and fees levied upon the Easement Land) or the rents collected
                 therefrom, by any governmental entity based upon the ownership,
                 leasing, renting or operation of the Building, the Fee Land or
                 the Easement Land, including all reasonable costs and expenses
                 of protesting any such taxes, assessments or fees. Taxes shall
                 not include any net income, capital stock, succession,
                 transfer, franchise, gift, estate or inheritance taxes;
                 provided, however, if at any time during the Term, a tax or
                 excise on income is levied or assessed by any governmental
                 entity, in lieu of or as a substitute for, in whole or in part,
                 real estate taxes or other ad valorem taxes, such tax shall
                                            ----------
                 constitute and be included in Taxes. For the purposes of
                 determining Taxes for any given year, the amount to be included
                 for such year (a) from special assessments payable in
                 installments shall be the amount of the installments (and any
                 interest) due and payable during such year, and (b) from all
                 other Taxes shall at Landlord's election either be the amount
                 accrued, assessed or otherwise imposed for such year or the
                 amount due and payable in such year.

          (viii) "Tenant's Proportionate Share" shall mean the percentage set
                 forth in Item 12 of the Schedule, which has been determined by
                 dividing the rentable square feet of floor area in the Premises
                 by the rentable square feet of floor area in the Building.

     B.   Components of Rent.  Tenant agrees to pay the following amounts to
          ------------------
Landlord at the office of the Building or at such other place as Landlord
designates:

          (i)    Base rent ("Base Rent") to be paid in monthly installments in
                 the amount set forth in Item 10 of the Schedule in advance on
                 or before the first day of each month of the Term commencing
                 with the Commencement Date, except that Tenant shall pay the
                 Base Rent due and payable for the first partial month and the
                 first full calendar month of the Term upon execution and
                 delivery of this Lease by Tenant.

                 Notwithstanding the foregoing, Landlord and Tenant hereby agree
                 that during the first lease year, on account of Landlord's
                 delivery of the Premises to Tenant in phases, as more
                 particularly described in section 4(B) below, Tenant shall pay
                 Base Rent as follows:

                                      -4-
<PAGE>

                 (a)   Tenant shall pay Base Rent for the Phase I Space
                       (hereinafter defined in section 4.A) at the MI rates and
                       in the amounts set forth in Item 10 of the Schedule and
                       as otherwise provided herein;

                 (b)   Tenant shall pay Base Rent for the Phase 11 Space
                       (hereinafter defined in section 4.A) in monthly
                       installments of $4,342 per month ($0.50 per rentable
                       square foot per month) beginning on the Commencement Date
                       until the earlier of (i) the date Tenant takes occupancy
                       of all or any portion of the Phase 11 Space, or (ii)
                       December 31, 1999. Thereafter Tenant shall pay Base Rent
                       for the Phase 11 Space at the full rates and in the
                       amounts set forth in Item 10 of the Schedule and as
                       otherwise provided herein; and

                 (c)   Tenant shall pay Base Rent for the Phase III Space
                       (hereinafter defined in section 4.A) in monthly
                       installments of $13,816 per month ($0.50 per rentable
                       square foot per month) beginning on the Commencement Date
                       until the earlier of (i) the date Tenant takes occupancy
                       of all or any portion of the Phase III Space, or (ii)
                       June 30, 2000. Thereafter Tenant shall pay Base Rent for
                       the entire Premises at the full rates and in the amounts
                       set forth in Item 10 of the Schedule and as otherwise
                       provided herein.

          (ii)   Adjustment rent ("Adjustment Rent") commencing on the first
                 anniversary of the Commencement Date (i.e., September 1, 2000)
                 in an amount equal to Tenant's Proportionate Share of (a) the
                 increase in Expenses for any calendar year during the Term over
                 the Base Expenses and (b) the increase in Taxes for any fiscal
                 year or partial fiscal year during the Term over the Base
                 Taxes. Prior to each calendar year or partial calendar year
                 during the Term, Landlord shall estimate the amount of
                 Adjustment Rent due for such calendar year, and Tenant shall
                 pay Landlord one-twelfth of such estimate on or before the
                 first day of each month during such calendar year. Such
                 estimate may be revised by Landlord whenever if obtains
                 information relevant to making such estimate more accurate.
                 After the end of each calendar year or partial calendar year
                 during the Term, Landlord shall deliver to Tenant a report
                 setting forth the actual Expenses and Taxes for such calendar
                 year and a statement of the amount of Adjustment Rent that
                 Tenant has paid and is payable for such calendar year. Within
                 thirty (30) days after receipt of such report and statement,
                 Tenant shall pay to Landlord the amount of Adjustment Rent due
                 for such calendar year minus any payments of Adjustment Rent
                 made by Tenant for such calendar year. If Tenant's estimated
                 payments of Adjustment Rent exceed the amount due Landlord for
                 such calendar year, Landlord shall apply such excess as a
                 credit against Tenant's other obligations under this Lease or
                 promptly refund such excess to Tenant if the Term has already
                 expired, provided Tenant is not then in default hereunder, in
                 either case without interest to Tenant.

          (iii)  Electricity payment ("Electricity Payment") to be paid within
                 ten (10) days of receipt of an invoice from Landlord specifying
                 the amount and cost of electricity utilized by Tenant in the
                 Premises as measured by the check meter(s) installed for the
                 Premises.

                                      -5-
<PAGE>

          (iv)   If Tenant has elected to receive a Tenant Improvement Advance
                 from Landlord (as defined in the Work Letter attached as
                 Exhibit D hereto), then commencing on September 1, 2000,
                 ---------
                 "Tenant Improvement Advance Amortization Payments" to be paid
                 by Tenant on a monthly basis in an amount calculated as
                 follows: Tenant Improvement Advance Amortization Payments shall
                 be in an amount which is necessary to fully amortize the
                 balance of Tenant Improvement Advances (including all interest
                 accrued thereon as provided in the Work Letter) over the
                 remainder of the Term of the Lease (disregarding any extension
                 periods), using an interest factor of 12% per annum, annual
                 posting of principal, and constant monthly payments. For
                 example, if Tenant requests a Tenant Improvement Advance of
                 $1,000 on January 1, 2000, Tenant would pay Landlord, beginning
                 on September 1, 2000, $21.89 (annual amortization of $1000,
                 plus $80 in accrued interest for the period from January 1,
                 2000 to August 31, 2000) per month in Tenant Improvement
                 Advance Amortization Payments over the remaining Term of the
                 Lease.

     C.   Payment of Rent.  The following provisions shall govern the payment of
          ---------------
Rent: (i) if this Lease commences or ends on a day other than the first day or
last day of a calendar month or year, respectively, the Rent for the month/year
in which this Lease so begins or ends shall be prorated and the monthly
installment(s) shall be adjusted accordingly; (ii) all Rent shall be paid to
Landlord without offset or deduction, and the covenant to pay Rent shall be
independent of every other covenant in this Lease; (iii) if during all or any
portion of any calendar year during the Term the Building is not at least
ninety-five percent (95%) occupied by tenants, Landlord may elect to make an
appropriate adjustment of Expenses for such calendar year to determine the
Expenses that would have been paid or incurred by Landlord had the Building been
at least ninety-five percent (95%) occupied by tenants for the entire calendar
year and the amount so determined shall be deemed to have been the Expenses for
such calendar year; (iv) any sum due from Tenant to Landlord which is not paid
within five (5) days of the date the same is due shall bear interest from the
date due until the date paid at the annual rate of the prime rate of Fleet
National Bank (or any successor bank thereto), plus four percent (4%), but in no
event higher than the maximum rate permitted by law (the "Default Rate"); and,
in addition, Tenant shall pay Landlord a late charge for any Rent payment which
is paid more than five (5) business days after its due date equal to five
percent (5%) of such payment; (v) if changes are made to this Lease or the
Building changing the number of square feet contained in the Premises or in the
Building, Landlord shall make an appropriate adjustment to Tenant's
Proportionate Share; (vi) Tenant shall have the right to inspect Landlord's
accounting records relative to Expenses and Taxes during normal business hours
at any time within ninety (90) days following the furnishing to Tenant of the
annual statement of Adjustment Rent; and, unless Tenant shall take written
exception to any item in any such statement within such ninety (90) day period,
such statement shall be considered as final and accepted by Tenant; (vii) in the
event of the termination of this Lease prior to the determination of any
Adjustment Rent, Tenant's agreement to pay any such sums and Landlord's
obligation to refund any such sums (provided Tenant is not in default hereunder)
shall survive the termination of this Lease; (viii) no adjustment to the Rent by
virtue of the operation of the rent adjustment provisions in this Lease shall
result in the payment by Tenant in any year of less than the Base Rent shown on
the Schedule; (ix) Landlord may at any time change the fiscal year of the
Building; (x) each amount owed to Landlord under this Lease for which the date
of payment is not expressly fixed shall be due on the same date as the Rent
listed on the statement showing such amount is due; and (xi) if Landlord fails
to give Tenant an estimate of Adjustment Rent prior to the beginning of any
calendar year, Tenant shall continue to pay Adjustment Rent at the rate for the
previous calendar year until Landlord delivers such estimate.

                                      -6-
<PAGE>

     3.   USE. Tenant agrees that it shall occupy and use the Premises only as
business offices, testing laboratory and research and development space for
electronics and computer equipment, and uses ancillary thereto and for no other
purposes. Tenant shall comply with all federal, state and local laws, ordinances
and regulations and all covenants, conditions and restrictions of record
applicable to Tenant's use or occupancy of the Premises. Without limiting the
foregoing, Tenant shall not cause, nor permit, any hazardous or toxic substances
to be brought upon, produced, stored, used, discharged or disposed of in, on or
about the Premises without the prior written consent of Landlord (except for
such substances and amounts as are typically used in Class A office buildings,
such as household cleaning agents, printing ink, etc.) and then only in
compliance with all applicable environmental laws.

     4.   CONSTRUCTION OF THE PREMISES.

     A.   Delivery of Possession.  Landlord shall deliver the Premises to Tenant
          ----------------------
in three phases.

          (i)   Phase I. Landlord shall deliver the entirety of the eleventh
                (11th) floor of Tower III of the Building (the "Phase I Space")
                on the Commencement Date.

          (ii)  Phase 11. On or before December 1, 1999, Landlord will notify
                --------
                Tenant of the location of an additional 8,684 rentable square
                feet of floor area for Tenant's occupancy, which shall be, at
                Landlord's option, on either the tenth (10th) or the twelfth
                (12th) floor of Tower III of the Building (the "Phase II
                Space"). Landlord shall thereupon deliver, and Tenant shall take
                occupancy of, the Phase 11 Space no later than January 1, 2000.

          (iii) Phase III.  Landlord shall deliver, and no later than July 1,
                ---------
                2000 Tenant shall take occupancy of, the remainder of the
                rentable space of the floor of Tower III on which the Phase 11
                Space is located, comprising the remaining 27,632 rentable
                square feet of such floor (the "Phase III Space")

          (iv)  Early Access. Tenant shall have the right to enter the Phase I
                ------------
                Space upon the Effective Date for purposes of commencing the
                Tenant's Work and/or installing telecommunications and computer
                cable, infrastructure improvements, and to perform certain other
                reasonable administrative functions. Tenant shall have the right
                to enter the Phase II Space and the Phase III Space thirty (30)
                days prior to the scheduled delivery date for the same purposes.

          (v)   Accelerated Delivery Dates. In the event Tenant wishes to take
                --------------------------
                occupancy of the Phase II Space and/or Phase III Space prior to
                the date Landlord is obligated to deliver the same, Tenant may
                notify Landlord in writing of the date on which it wishes to
                take occupancy of such space. Without increasing any of
                Landlord's obligations with respect to the delivery of any
                portion of the Premises, Landlord will notify Tenant of the
                space available for occupancy, and endeavor to deliver such
                space as soon as reasonably possible under the circumstances.

     B.   Condition of Premises.  Other than as specified in the Work Letter
          ---------------------
attached hereto as Exhibit D, Landlord shall deliver the Premises to Tenant
"broom clean", but otherwise "as is, where is, with all faults" and without any
express or implied representations or warranties of any kind (including, without
limitation, any

                                      -7-
<PAGE>

warranties of merchantability, fitness or habitability), and no agreement of
Landlord to after, remodel, decorate, clean or improve the Premises or the
Building or the Property (or to provide Tenant with any credit or allowance for
the same) has been made, and no representation regarding the condition of the
Premises or the Building or the Property or the suitability of the Premises for
Tenant's proposed use thereof have been made, by or on behalf of Landlord or
relied upon by Tenant, except as expressly provided elsewhere in this Lease.

     C.   Tenant's Work. Tenant shall, at Tenant's cost and expense, design and,
          -------------
upon its receipt of possession of the Premises, install improvements to the
Premises (the "Tenant's Work"), based on the sketch plan attached hereto
               -------------
as Exhibit C (the "Sketch Plan"), substantially in accordance with the terms,
   ---------       -----------
conditions, and specifications listed on Exhibit D hereto (the "Work Letter").
                                         ---------              -----------

     5.   UTILITIES AND OTHER SERVICES.

     A.   Utilities and Services Furnished by Landlord.  Landlord agrees to
          --------------------------------------------
furnish or cause to be furnished to the Premises the utilities and services
described in Exhibit E attached hereto and incorporated herein by this reference
(hereinafter referred to collectively as "Landlord's Services"), subject to the
conditions and in accordance with the standards set forth in this Section 5 and
in the attached Exhibit E. All costs and expenses incurred by Landlord in
connection with furnishing Landlord's Services shall be included as part of
Expenses pursuant to Section 2 hereof except for the cost of furnishing
electrical energy to the Premises as provided in the attached Exhibit E.

Landlord shall furnish electrical energy to the Premises as provided in the
attached Exhibit E. As described in Section 2(B)(iii) hereof, Tenant shall pay
to Landlord the Electricity Payment, as additional rent, to cover the cost of
the electricity consumed on the Premises during the Term. Consumption of
electricity in the Premises will be measured by check meter. Periodically after
the Commencement Date, Landlord shall determine the actual cost of electricity
consumed on the Premises by reading the check meter for the Premises and by
applying the Electric Rate(s) applicable to the period covered by such reading.

The phrase "Electric Rate" shall mean the composite effective rate per kilowatt-
hour taking into account the base utility rate, fuel adjustment factor, premium
charges or credits for hours of use, and any other charges which Landlord is
required to pay in connection with furnishing electricity to the Building.
Tenant shall pay to Landlord within ten (10) days after receipt of an invoice
therefor the cost of electricity consumed on the Premises for the period covered
by any reading of the check meter for the Premises as reflected on such invoice.

     B.   Special and Additional Usage.  Landlord may impose a reasonable charge
          ----------------------------
for any utilities and services, including without limitation, air conditioning,
electricity, and water, provided by Landlord by reason of (i) any use of the
Premises at any time other than the hours set forth above or in the attached
Exhibit E; (ii) any use beyond what Landlord agrees herein or in the attached
Exhibit E to furnish; or (iii) special electrical, cooling and ventilating needs
created by Tenant's telephone equipment, computers, electronic data processing
equipment and other similar equipment or uses.

     C.   Cooperation; Payment of Charges; Approval of Special Equipment Usage.
          --------------------------------------------------------------------
Tenant agrees to cooperate fully at all times with Landlord and to abide by all
reasonable regulations and requirements which Landlord may prescribe for the use
of the above utilities and services. Tenant agrees to pay any charge imposed by
Landlord pursuant to Sections A and B above and any failure to pay any excess
costs as described above shall constitute a breach of the obligation to pay Rent
under this Lease and shall entitle Landlord to the rights herein

                                      -8-
<PAGE>

granted for such breach and shall entitle Landlord to immediately discontinue
providing such additional or special service * Tenant's use of electricity shall
at no time exceed the capacity of the service to the Premises or the electrical
risers or wiring installation .

     D.   Failure, Stoppage or Interruption of Service, No Release from
          -------------------------------------------------------------
Obligations.  Landlord shall not be liable for, and Tenant shall not be entitled
-----------
to any abatement or reduction of Rent by reason cf, Landlord's failure to
furnish any of the foregoing services when such failure is caused by accident,
breakage, repairs, riots, strikes, lockouts or other labor disturbance or labor
dispute of any character, governmental regulation, moratorium or offier
governmental action, inability by exercise of reasonable diligence to obtain
electricity, water or ftiel, or by any other cause beyond Landlord's immediate
control or for stoppages or interruptions of any such services for the purpose
of making necessary repairs or improvements. Landlord will use reasonable
efforts to minimize, to the extent possible, stoppages and interruptions of any
such services during the normal business hours of the Building. Failure,
stoppage or interruption of any such service shall not be construed as an actual
or constructive eviction or as a partial eviction against Tenant, or release
Tenant from the prompt and punctual performance by Tenant of the covenants
contained herein or operate to abate Rent.

     E.   Limitation and Unavailability of Service.  Anything hereinabove to the
          ----------------------------------------
contrary notwithstanding, Landlord and Tenant agree that Landlord's obligation
to furnish heat, electricity, air conditioning and/or water to the Premises
shall be subject to and limited by all laws, rules, and regulations of any
governmental authority affecting the supply, distribution, availability,
conservation or consumption of energy, including, but not limited to, heat,
electricity, gas, oil and/or water. Landlord shall abide by all such
governmental laws, rules and regulations and, in so doing, Landlord shall not be
in default in any manner whatsoever under the terms of this Lease, and
Landlord's compliance therewith shall not affect in any manner whatsoever
Tenant's obligation to pay the full Rent set forth in this Lease.

     F.   Load Bearing Capacity.  Tenant shall not place a load upon any floor
          ---------------------
of the Premises which exceeds the load per square foot which such floor was
designed to carry and which is allowed by law. Landlord reserves the right to
prescribe in a reasonable manner the weight and position of all safes and heavy
installations which Tenant wishes to place in the Premises so as to properly
distribute the weight thereof.

     G.   Unreasonable Noise or Vibration.  Business machines and mechanical
          -------------------------------
equipment belonging to Tenant which cause unreasonable noise or vibration that
may be transmitted to the structure of the Building or to any leased space to
such a degree as to be objectionable to Landlord or to any tenants in the
Building shall be placed and maintained by Tenant, at Tenant's expense, on
vibration eliminators or other devices sufficient to eliminate such unreasonable
noise or vibration.

     H.   Telephone.  Subject to applicable codes, Landlord has or will cause to
          ---------
be installed telephone risers (collectively the "risers") from the outside of
the Building to the telephone room (the "telephone room") serving the Premises.
Tenant shall have the right to use the risers by installing telephone lines (the
"telephone lines") from the Premises to the telephone room if and to the extent
such telephone lines are not now in place. Landlord makes no representations or
warranties with respect to the capacity, suitability or design of the risers,
the telephone room or the telephone lines. If there is more than one tenant on a
floor, Landlord shall allocate hookups to the telephone room based on the
proportion of rentable square feet that each tenant occupies on the floor. The
installation and hook-up of telephone lines by Tenant shall be subject to all of
the terms and conditions of this Lease, including, without limitation, Section 9
of this Lease. Landlord shall not be liable for, and Tenant waives all claims
with respect to, any damages or losses sustained by Tenant or by any occupant of
the Premises,

                                      -9-
<PAGE>

including, without limitation, any compensatory, property or consequential
damages, resulting from the 'operation or maintenance of the risers, telephone
rooms and telephone lines, including, without limitation, (i) any damage to
Tenant's telephone lines, telephones or other equipment connected to the
telephone lines, or (ii) interruption or failure of, or interference with,
telephone or other service coming through the telephone lines to the Premises.

     I.   Supplemental HVAQ Equipment.  Tenant acknowledges that the portion of
          ---------------------------
the Premises on the 11th floor of the Building contains two supplemental cooling
units, associated components located on the roof of the Building, and connecting
conduits (the "Supplemental Cooling Equipment"). While the Supplemental Cooling
Equipment shall remain the property of Landlord, Landlord grants Tenant
permission to make use of the Supplemental Cooling Equipment so long as Tenant:
(i) arranges for regular, professional maintenance of the Supplemental Cooling
Equipment by a contractor approved by Landlord, (ii) pays all electricity and
other utility charges associated with the operation and maintenance of the
Suppiemental Cooling Equipment, and (iii) accepts sole responsibility for any
loss, cost or damage (exclusive of normal wear and tear) suffered by Landlord or
Tenant arising out of the presence or operation of the Supplemental Cooling
Equipment. Tenant shall have the right to relocate the Supplemental Cooling
Equipment within the Premises, subject to the requirements of Section 9 hereof
regarding alterations.

     6.   RULES AND REGULATIONS. Tenant shall observe and comply and shall cause
its subtenants, assignees, invitees, employees, contractors' and agents to
observe and comply with the rules and regulations listed on Exhibit F attached
                                                            ---------
hereto and incorporated herein by this reference and with such reasonable
modifications and additions thereto as Landlord may make from time to time.
Landlord shall not be liable for failure of any person to obey such rules and
regulations. Landlord shall not be obligated to enforce such rules and
regulations against any person, and the failure of Landlord to enforce any such
rules and regulations shall not constitute a waiver thereof or relieve Tenant
from compliance therewith.

     7.   CERTAIN RIGHTS RESERVED TO LANDLORD. Landlord reserves the following
rights, each of which Landlord may exercise without notice to Tenant and without
liability to Tenant, and the exercise of any such rights shall not be deemed to
constitute an eviction or disturbance of Tenant's use or possession of the
Premises and shall not give rise to any claim for set-off or abatement of rent
or any other claim: (a) to change the name or street address of the Building or
the suite number of the Premises; (b) to install, affix and maintain any and all
signs on the exterior or interior of the Building; (c) to make repairs,
decorations, alterations, additions, or improvements, whether structural or
otherwise, in and about the Building, and for such purposes to enter upon the
Premises, temporarily close doors, corridors and other areas in the Building and
interrupt or temporarily suspend services or use of common areas, and Tenant
agrees to pay Landlord for overtime and similar expenses incurred if such work
is done other than during ordinary business hours at Tenant's request (provided
Landlord shall use reasonable efforts, to the extent reasonably possible and
commercially prudent, in Landlord's discretion, to mitigate any material
disruption to the business of Tenant and other Tenants in the Building from
Landlord's exercising such rights); (d) to retain at all times, and to use in
appropriate instances, keys to all doors within and into the Premises; (e) to
grant to any person or to reserve unto itself the exclusive right to conduct any
business or render any service in the Building; (f) to show or inspect the
Premises at reasonable times and, if vacated or abandoned, to prepare the
Premises for reoccupancy; (g) to install, use and maintain in and through the
Premises, pipes, conduits, wires and ducts serving the Building, provided that
such installation, use and maintenance does not unreasonably interfere with
Tenant's use of the Premises; (h) to take any other action which Landlord deems
reasonable in connection with the operation, maintenance or preservation of the
Building; and (i) to comply with the provisions of any mortgage or deed of trust
encumbering fee title to the Property (a "mortgage").

                                     -10-
<PAGE>

     8.   MAINTENANCE AND REPAIRS. Tenant, at its expense, shall maintain and
keep the Premises neat and clean and in good order and repair at all times
during the Term. In addition, Tenant shall reimburse Landlord for the cost of
any repairs to the Building necessitated by the acts or omissions of Tenant, its
subtenants, assignees, invitees, employees, contractors and agents, to the
extent Landlord is not reimbursed for such costs under its insurance policies.
Subject to the preceding sentence, Landlord shall perform any maintenance or
make any repairs to the Building as Landlord shall desire or deem necessary for
the safety, operation or preservation of the Building, or as Landlord may be
required or requested to do by any governmental authority or by the order or
decree of any court or by any other proper authority.

Except as otherwise provided in Sections 12 and 13 below and subject to Tenant's
obligations set forth in the preceding paragraph or elsewhere in this Lease,
Landlord shall keep and maintain or cause to be kept and maintained the
structural components of the Building (including, without limitation, the roof
and the roof membrane), all common areas of the Property, and all Building
systems (excluding only those non-standard portions of Building systems which
are located within a tenant's premises and service only such tenant's premises)
in a neat, safe and orderly condition and shall make all necessary repairs
thereto. Except as otherwise provided in this Lease, the cost of all such
maintenance shall be borne by Landlord and shall be included as part of
Expenses.

     9.   ALTERATIONS

     A.   Requirements.  Tenant shall not make any replacement, alteration,
          ------------
improvement or addition to or removal from the Premises (collectively an
"alteration") costing more than $5,000 to complete without the prior written
consent of Landlord, which consent shall not be unreasonably withheld or
delayed. In the event Tenant proposes to make any alteration, Tenant shall,
prior to commencing such alteration, submit to Landlord for prior written
approval: (i) detailed plans and specifications; (ii) sworn statements,
including the names, addresses and copies of contracts for all contractors;
(iii) all necessary permits evidencing compliance with all applicable
governmental rules, regulations and requirements; (iv) certificates of insurance
in form and amounts required by Landlord, naming Landlord and any other parties
designated by Landlord as additional insureds; and (v) all other documents and
information as Landlord may reasonably request in connection with such
alteration. Tenant agrees to pay Landlord's standard charges for review of all
such items and supervision of the alteration, which charge as of the date of
this Agreement is five (5%) percent of the cost of the alteration. Neither
approval of the plans and specifications nor supervision of the alteration by
Landlord shall constitute a representation or warranty by Landlord as to the
accuracy, adequacy, sufficiency or propriety of such plans and specifications or
the quality of workmanship or the compliance of such alteration with applicable
law. Tenant shall pay the entire cost of the alteration and, if reasonably
requested by Landlord, shall deposit with Landlord prior to the commencement of
the alteration, security for the payment and completion of the alteration in
form and amount required by Landlord. Each alteration shall be performed in a
good and workmanlike manner, in accordance with the plans and specifications
approved by Landlord, and shall meet or exceed the standards for construction
and quality of materials established by Landlord for the Building. In addition,
each alteration shall be performed in compliance with all applicable
governmental and insurance company laws, regulations and requirements. Each
alteration shall be performed by union contractors if reasonably required by
Landlord and in harmony with Landlord's employees, contractors and other
tenants. Each alteration, whether temporary or permanent in character, made by
Landlord or Tenant in or upon the Premises (excepting only Tenant's furniture,
equipment and trade fixtures) shall become Landlord's property and shall remain
upon the Premises at the expiration or termination of this Lease without
compensation to Tenant; provided, however, that Landlord shall have the right to
require Tenant to remove such alteration at Tenant's sole cost and expense in
accordance with the provisions

                                     -11-
<PAGE>

of Section 15 of this Lease. Notwithstanding the foregoing, in the event of any
permitted alteration costing Tenant more than $100,000 to fully complete,
Landlord shall notify Tenant prior to Tenant's commencing such alteration work
whether Landlord shall require removal of such alteration by Tenant at the end
of the Term, and Tenant shall be entitled to rely on such notice.

Tenant acknowledges that the Premises may constitute a place of public
accommodation or a commercial facility under Title III of the Americans with
Disabilities Act (the "ADA") and that the ADA is applicable to both an owner and
a lessee of a place of public accommodation or commercial facility. Tenant
further acknowledges that under the ADA any alteration to the Premises must
comply with accessibility standards set forth in the rules promulgated by the
Department of Justice at 28 C.F.R. 36. 101 et. seq.  Notwithstanding anything in
this Lease to the contrary, in the event Tenant makes any alteration to the
Premises or conducts itself in a manner which would require compliance with
Title III of the ADA and the accessibility standards promulgated by the
Department of Justice, Tenant agrees to design and build such alterations to the
Premises and/or to conduct itself in such a fashion as to comply with the ADA
and the accessibility standards.

     B.   Liens.  Upon completion of any alteration, Tenant shall promptly
          -----
furnish Landlord with sworn owner's and contractors statements and full and
final waivers of lien covering all labor and materials included in such
alteration. Tenant shall not permit any mechanic's lien to be filed against the
Building, or any part thereof, arising out of any alteration performed, or
alleged to have been performed, by or on behalf of Tenant. If any such lien is
filed, Tenant shall within ten (10) days thereafter (or such shorter period as
required by the terms of any mortgage, provided Tenant has received notice of
such shorter period) have such lien released of record or deliver to Landlord a
bond in form, amount, and issued by a surety satisfactory to Landlord,
indemnifying Landlord and the holder of a mortgage (a "mortgagee") against all
costs and liabilities resulting from such lien and the foreclosure or attempted
foreclosure thereof. If Tenant fails to have such lien so released or to deliver
such bond to Landlord, Landlord or a mortgagee, without investigating the
validity of such lien, may pay or discharge the same; and Tenant shall reimburse
Landlord or the mortgagee, as applicable, upon demand for the amount so paid by
Landl6rd or the mortgagee, including Landlord's reasonable and actual expenses
and attorneys' fees.

     10.  INSURANCE

     A.   Tenant's Insurance.  Tenant, at its expense, shall maintain at all
          ------------------
times during the Term the following insurance policies: (i) all risk or
equivalent special form coverage insuring the full replacement cost of all
improvements, alterations or additions to the Premises made at Tenant's expense,
and all other property owned or used by Tenant and located in the Premises; (ii)
commercial general liability insurance, contractual liability insurance and
property damage insurance with respect to the Building and the Premises, with
limits to be set by Landlord from time to time but in any event not less than
$3,000,000.00 combined single limit for personal injury, sickness or death or
for damage to or destruction of property for any one occurrence; and (iii)
insurance against such other risks and in such other amounts as Landlord may
from time to time reasonably require. The form of all such policies and
deductibles thereunder shall be subject to Landlord's prior reasonable approval.
All such policies shall be issued by insurers reasonably acceptable to Landlord
and licensed to do business in The Commonwealth of Massachusetts and shall
contain a waiver of any rights of subrogation thereunder. In addition, the
policies shall name Landlord, the mortgagee and its agents, and any other
parties designated by Landlord as additional insureds, shall require at least
thirty (30) days' prior written notice to Landlord, the mortgagee, and such
other parties designated by Landlord of termination or modification and shall be
primary and not contributory. Tenant shall at least fifteen (15) days prior to
the Commencement Date, and within fifteen (15) days prior to the expiration of
each such policy, deliver to Landlord either a duplicate original of all
insurance

                                     -12-
<PAGE>

policies required to be maintained by Tenant hereunder or Evidence of Insurance
(in form ACORD 27 or its equivalent) for each such policy evidencing the
foregoing insurance or renewal thereof, as the case may be.

     B.   Landlord's Insurance.  Landlord shall take out and maintain in force
          --------------------
throughout the Term, in a company or companies authorized to do business in The
Commonwealth of Massachusetts, (i) casualty insurance on the Building in an
amount equal to the full replacement value of the Building (exclusive of
foundations), covering all risks of direct physical loss or damage and so-called
"extended coverage" risks and (ii) commercial general liability insurance with
respect to the Building and Property in such amounts as Landlord may from time
to time deem necessary or desirable. Any insurance required to be maintained by
Landlord hereunder may be maintained in the form of a blanket policy covering
the Building as well as other properties owned by Landlord or affiliates of
Landlord so long as the blanket policy does not reduce the limits nor diminish
the coverage required herein.

     11.  WAIVER AND INDEMNITY.

     A.   Waiver.  Tenant releases Landlord, its property manager and their
          ------
respective agents and employees from, and waives all claims for, damage or
injury to person or property and loss of business sustained by Tenant and
resulting from the Building or the Premises or any part thereof or any equipment
therein becoming in disrepair, or resulting from any accident in or about the
Building. This paragraph shall apply particularly, but not exclusively, to
flooding, damage caused by Building equipment and apparatus, water, snow, frost,
steam, excessive heat or cold, broken glass, sewage, gas, odors, excessive noise
or vibration or the bursting or leaking of pipes, plumbing fixtures or sprinkler
devices. Without limiting the generality of the foregoing, Tenant waives all
claims and rights of recovery against Landlord, its property manager and their
respective agents and employees for any loss or damage to any property of
Tenant, which loss or damage is insured against, or required to be insured
against, by Tenant pursuant to Section 10 above, whether or not such loss or
damage is due to the fault or negligence of Landlord, its property manager or
their respective agents or employees, and regardless of the amount of insurance
proceeds collected or collectible under any insurance policies in effect.

     B.   Indemnity.  Tenant agrees to indemnify, defend and hold harmless
          ---------
Landlord, its property manager and their respective agents and employees, from
and against any and all claims, demands, actions, liabilities, damages, costs
and expenses (including attorneys' fees), for injuries to any persons and damage
to or theft or misappropriation or loss of property occurring in or about the
Building and arising from the use and occupancy of the Premises or from any
activity, work, or thing done, permitted or suffered by Tenant in or about the
Premises (including, without limitation, any alteration by Tenant) or from any
breach or default on the part of Tenant in the performance of any covenant or
agreement on the part of Tenant to be performed under this Lease or due to any
other act or omission of Tenant, its subtenants, assignees, invitees, employees,
contractors and agents. Without limiting the foregoing, Tenant shall indemnify,
defend and hold Landlord harmless from any claims, liabilities, damages, costs
and expenses arising out of the use or storage of hazardous or toxic materials
in the Building by Tenant. If any such proceeding is filed against Landlord or
any such indemnified party, Tenant agrees to defend Landlord or such party in
such proceeding at Tenant's sole cost by legal counsel reasonably satisfactory
to Landlord, if requested by Landlord.

     12.  FIRE AND CASUALTY

     A.   Obligation to Repair or Rebuild.  If the Premises or the Building
          -------------------------------
shall be damaged or destroyed by fire or other casualty, Tenant shall promptly
notify Landlord of any damage or destruction to the Premises of which Tenant has
knowledge or is aware, and Landlord, subject to its mortgagee's consent and to
the conditions

                                     -13-
<PAGE>

set forth in this Section 12, shall repair, rebuild or replace such damage and
restore the Premises and/or the Building, subject to Section 12(D) and Section
12(F) below, to substantially the same condition in which they were immediately
prior to such damage or destruction including restoration of the Base Building
Elements (as defined in the Work Letter attached hereto as Exhibit D, but
specifically excluding items (vii) and (viii) thereof); provided, however, that
Landlord shall only be obligated to restore such damage which is covered by its
fire and all risk insurance policy or policies.

     B.   Commencement and Completion of Work.  The work shall be commenced
          -----------------------------------
promptly and co~ipleted with due diligence, taking into account the time
required by Landlord to effect a settlement with, and procure insurance proceeds
from, the insurer, and for delays beyond Landlord's reasonable control.

     C.   Application of Proceeds. The net amount of any insurance proceeds
          -----------------------
(excluding proceeds received pursuant to any rental interruption coverage
obtained by Landlord), recovered by reason of the damage or destruction of the
Building in excess of the cost of adjusting the insurance claim and collecting
the insurance proceeds (such excess amount being hereinafter called the "net
insurance proceeds") shall be applied towards the reasonable cost of the work
required to be performed by Landlord under this Section 12. If the net insurance
proceeds are more than adequate to complete such work, the amount by which the
net insurance proceeds exceed the cost of such work shall be retained by
Landlord.

     D.   Tenant's Personal Property and Alterations.  Landlord's obligation or
          ------------------------------------------
election to restore the Premises under this Section 12 shall not include the
repair, restoration or replacement of the furniture or any other personal
property owned by or in the possession of Tenant. In addition, Landlord shall
not be under any obligation to repair, restore or replace any alterations or
improvements to the Premises made by or on behalf of Tenant.

     E.   Abatement of Rent.  Tenant will receive an abatement of Rent to the
          -----------------
extent and during the time the Premises are rendered untenantable due to a fire
or other casualty, such Rent to abate in such proportion as the part of the
Premises thus destroyed or rendered untenantable bears to the total Premises
from the date of such damage or destruction and until the earlier of the date
that (i) Landlord obtains a certificate of occupancy with respect to completion
of the work upon the Premises required to be performed by Landlord under this
Section 12 or (ii) Tenant recommences use of such part of the Premises and, in
cases in which the Premises are being restored by Landlord, to be conditioned
upon Tenant not occupying such part of the Premises for the conduct of business.
If the Premises are so slightly damaged by such fire or other casualty as not to
be rendered in any part unteriantable, Landlord shall complete the work upon the
Premises required to be performed by Landlord under this Section 12 with
reasonable promptness and the payment of Rent shall not be affected thereby.
Tenant shall, at its own cost and expense, remove so much of its furniture and
furnishings and other belongings from the Premises as Landlord shall require in
order to perform the work required to be performed by Landlord under this
Section 12.

     F.   Landlord's Option Not to Restore.  Notwithstanding any of the
          --------------------------------
foregoing provisions of this Section 12 to the contrary, if there is substantial
damage to the Building due to a fire or other casualty, or if, in the judgment
of Landlord's architect, damage to the Premises due to a fire or other casualty
is such that the work upon the Premises required to be performed by Landlord
under this Section 12 with respect to such fire or other casualty cannot be
completed within ninety (90) days after such fire or other casualty, then
Landlord shall have the option not to perform the work upon the Premises
required to be performed by Landlord under this Section 12 with respect to such
fire or other casualty, and may elect to terminate this Lease by sending a
written notice of

                                     -14-
<PAGE>

such termination to Tenant, the notice to specify a termination date not less
than thirty (30) days after its transmission. Landlord shall notify Tenant in
writing within sixty (60) days after the date of such fire or other casualty of
such architect's estimate of the period of time required to perform the work
upon the Premises required to be performed by Landlord with respect to such fire
or other casualty.

     G.   Tenant's Right to Terminate.  Notwithstanding anything herein to the
          ---------------------------
contrary, if the Premises are damaged by a fire or other casualty, then (i) if
the fire or other casualty occurs prior to the date which is two hundred seventy
(270) before the Expiration Date (as it may be extended pursuant to the Tenant's
Renewal Option) and if Landlord fails to complete the work upon the Premises
required to be performed by Landlord under this Section 12 with respect to such
fire or other casualty within two hundred seventy (270) days after such fire or
other casualty, Tenant may terminate this Lease by notice given to Landlord at
any time after the end of such two hundred seventy (270) day repair period but
prior to the date that Landlord has completed the work upon the Premises
required to be performed under this Section 12 with respect to such fire or
other casualty, and (ii) if the fire or other casualty occurs within two hundred
seventy (270) days of the Expiration Date (as it may be extended pursuant to the
Tenant's Renewal Option) and if as a consequence of such fire or other casualty
the Premises are rendered substantially unusable, the Tenant may terminate this
Lease by notice given to Landlord within thirty (30) days of the date on which
the fire or other casualty occurs.

     13.  CONDEMNATION. If the Premises or the Building is rendered untenantable
by reason of a condemnation (or by a deed given in lieu thereof), then either
party may terminate this Lease by giving written notice of termination to the
other party within thirty (30) days after such condemnation, in which event this
Lease shall terminate effective as of the date of such condemnation. If this
Lease so terminates, Rent shall be paid through and apportioned as of the date
of such condemnation. If such condemnation does not render the Premises or the
Building untenantable, this Lease shall continue in effect and Landlord shall
promptly restore the portion not condemned to the extent reasonably possible to
the condition existing prior to the condemnation. In such event, however,
Landlord shall not be required to expend an amount in excess of the proceeds
received by Landlord from the condemning authority. Landlord reserves all rights
to compensation for any condemnation (except for any awards payable directly to
Tenant for relocation expenses and except for any award for alterations to the
Premises paid for by Tenant except to the extent any such award diminishes the
award payable to Landlord on account of any such condemnation). Tenant hereby
assigns to Landlord any right Tenant may have to such compensation (except as
provided in the immediately preceding sentence), and Tenant shall make no claim
against Landlord or the condemning authority for compensation (except as
provided in the immediately preceding sentence) for termination of Tenant's
leasehold interest under this Lease or interference with Tenant's business.

     14.  ASSIGNMENT AND SUBLETTING.

     A.   Landlord's Consent.  Tenant shall not, without the prior written
          ------------------
consent of Landlord: (i) assign, convey, mortgage or otherwise transfer this
Lease or any interest hereunder, or sublease the Premises, or any part thereof,
whether voluntarily or by operation of law; or (ii) permit the use of the
Premises or any part thereof by any person other than Tenant and its employees.
Any such transfer, sublease or use described in the preceding sentence (herein
referred to as a "Transfer", which term shall include any reassignment of this
Lease after any initial assignment of this Lease by the Tenant named herein, or
any subsequent reassignment and any assignment of any sublease with respect to
all or any portion of the Premises and any subsubleasing of any portion of the
Premises previously subleased) occurring without the prior written consent of
Landlord shall be void and of no

                                     -15-
<PAGE>

effect. Landlord's consent to any Transfer shall not constitute a waiver of
Landlord's right to withhold its consent to any future Transfer. Landlord's
consent to any Transfer or acceptance of rent from any party other than Tenant
shall not release Tenant from any covenant or obligation under this Lease.
Landlord may require as a condition to its consent to any assigninent of this
Lease that the assignee execute an instrument in which such assignee assumes the
obligations of Tenant hereunder. For the purposes of this paragraph, the
transfer (whether direct or indirect) of all or substantially all of Tenant's
assets (including Tenant's interest under this Lease), all or a majority of the
capital stock in a corporate Tenant (whether by private sale or public offering
of such stock), or the merger, consolidation or reorganization of such Tenant,
or the transfer of all or any general partnership interest in any partnership
Tenant, shall not be considered a Transfer provided that (exrept in case of a
public offering of stock of a corporate Tenant) the Transferee of such assets or
interest shall in all events have a positive net worth, as reasonably determined
by Landlord.

     B.   Standards for Consent.  If Tenant desires the consent of Landlord to
          ---------------------
a Transfer, Tenant shall submit to Landlord, at least forty-five (45) days prior
to the proposed effective date of the Transfer, a written notice which includes
such information as Landlord may require about the proposed Transfer and the
transferee. If Landlord does not terminate this Lease, in whole or in part,
pursuant to Section 14(C), Landlord shall not unreasonably withhold its consent
to any assignment or sublease. Landlord shall provide Tenant with notice of its
grant or withholding of consent within thirty (30) days of receipt of Tenant's
notice described in the first sentence of this Section 14(B). Landlord shall not
be deemed to have unreasonably withheld its consent if, in the judgment of
Landlord (without implied limitation): (i) the transferee is of a character or
engaged in a business which is not in keeping with the standards or criteria
used by Landlord in leasing the Building; (ii) the financial condition of the
transferee is such that it may not be able to perform its obligations in
connection with this Lease; (iii) the purpose for which the transferee intends
to use the Premises or portion thereof is in violation of the terms of this
Lease or the lease of any other tenant in the Building; (iv) the transferee is a
current tenant of the Building or is a user who is then, or has at any time
during the Term been, in negotiations with Landlord for space at the Property
and such transferee's space needs could be accommodated by space available in
the Building under a direct lease from Landlord; (v) the rent to be charged the
transferee is less than the then fair market rental value of space in the
Building (which fair market rental value shall be deemed to be the rent set
forth in the most current lease by Landlord of space in the Building); or (vi)
consent to the Transfer would violate the terms and provisions of a mortgage. If
Landlord wrongfully withholds its consent to any Transfer, Tenant's sole and
exclusive remedy therefor shall be to seek specific performance of Landlord's
obligation to consent to such Transfer. If Landlord consents to any Transfer,
Tenant shall pay to Landlord one hundred percent (100%) of all rent and other
consideration received by Tenant in excess of the Rent paid by Tenant hereunder
for the portion of the Premises so transferred(after first deducting therefrom
all reasonable costs incurred by Tenant in connection therewith, including,
without limitation, reasonable legal, brokerage, space planning, and
construction costs in connection therewith, proviaed, however, that at
Landlord's option, Landlord shall have the right to require Tenant to deduct
such costs by amortizing such costs on a straight-line basis over the remaining
Term of the Lease (and including any Renewal Term, if so exercised) in equal
monthly amounts). Such rent shall be paid as and when received by Tenant. In
addition, Tenant shall pay to Landlord any attorneys' fees and expenses incurred
by Landlord in connection with any proposed Transfer, whether or not Landlord
consents to such Transfer.

     C.   Recapture.  Landlord shall have the right to terminate this Lease as
          ---------
to that portion of the Premises covered by a Transfer. Landlord may exercise
such right to terminate by giving notice to Tenant at any time within thirty
(30) days after the date on which Tenant has furnished to Landlord all of the
items required under Section 14(B) above. If Landlord exercises such right to
terminate, Landlord shall be entitled to recover

                                     -16-
<PAGE>

possession of, and Tenant shall surrender such portion of, the Premises (with
appropriate dernising partitions erected at the expense of Tenant) on the later
of (i) the effective date of the proposed Transfer, or (ii) ninety (90) days
after the date of Landlord's notice of termination. In the event Landlord
exercises such right to terminate, Landlord shall have the right to enter into a
lease with the proposed transferee without incurring any liability to Tenant on
account thereof. Notwithstanding the foregoing, Landlord's right to terminate
this Lease shall not apply to a proposed sublease of some or all of the Phase 11
Premises or the Phase III Premises which sublease is entered into prior to June
30, 2000 and which sublease has a term (including any option periods) which
extends to a date not later than June 30, 2001.

     D.   No Release.  In no event shall any Transfer release or relieve Tenant
          ----------
from its obligations to fully observe or perforin all of the terms, covenants
and conditions of this Lease on its part to be observed or performed (including
liability arising during any renewal term of this Lease or with respect to any
expansion space included in the Premises). It is agreed that the liabilities and
obligations of Tenant hereunder are enforceable either before, simultaneously
with or after proceeding against any assignee, sublessee or other transferee of
Tenant.

     15.  SURRENDER. Upon the expiration or earlier termination of the Term or
Tenant's right to possession of the Premises (and subject to the provisions of
Sections 12 and 13 hereof), Tenant shall return the Premises to Landlord broom
clean, and in good order and condition, ordinary wear only excepted. If Landlord
requires Tenant to remove any alterations pursuant to Section 9 above, then such
removal shall be done in a good and workmanlike manner; and, upon such removal,
Tenant shall restore the Premises to its condition prior to the installation of
such alterations. If Tenant does not remove such alterations after request to do
so by Landlord, Landlord may remove the same and restore the Premises; and
Tenant shall pay the cost of such removal and restoration to Landlord upon
demand. Tenant shall also remove its furniture, equipment, trade fixtures and
all other items of personal property from the Premises prior to the expiration
or earlier termination of the Term or Tenant's right to possession of the
Premises. If Tenant does not remove such items prior to the expiration or
earlier termination of the Term or Tenant's right to possession of the Premises,
Tenant shall be conclusively presumed to have conveyed the same to Landlord
without further payment or credit by Landlord to Tenant; or at Landlord's sole
option such items shall be deemed abandoned, in which event Landlord may cause
such items to be removed and disposed of at Tenant's expense, without notice to
Tenant and without obligation to compensate Tenant.

     16.  DEFAULTS AND REMEDIES.

     A.   Default.  The occurrence of any of the following shall constitute a
          -------
default (a "Default") by Tenant under this Lease:

          (i)  Tenant fails to pay any Rent when due and such failure to pay is
               not cured within five (5) days after written notice from
               Landlord; however, a Default shall occur without any obligation
               of Landlord to give any notice if Landlord has given Tenant
               written notice under this Section 16(A)(i) on more than two (2)
               occasions during the twelve (12) month interval preceding such
               failure to pay by Tenant;

          (ii) Tenant fails to perform or observe any other covenant or
               obligation of Tenant set forth in this Lease and such failure to
               perforin is not cured within thirty (30) days (or iminediately if
               the failure involves a hazardous condition) after notice from
               Landlord, or, in the case of

                                     -17-
<PAGE>

                a failure to observe any other covenant or obligation of Tenant
                set forth in this Lease which is not reasonably curable within
                thirty (30) days after notice from Landlord, Tenant fails to
                commence the cure of such failure promptly upon receipt of
                notice from Landlord to Tenant, or Tenant fails continuously to
                prosecute the cure of such failure, or Tenant fails to achieve
                such cure within ninety (90) days after such notice from
                Landlord to Tenant;

          (iii) the leasehold interest of Tenant is levied upon or attached
                under process of law and is not removed or bonded over to the
                satisfaction of Landlord within thirty (30) days;

          (iv)  Tenant or any guarantor of this Lease dies or dissolves;

          (v)   Tenant abandons or vacates the Premises; or

          (vi)  any voluntary or involuntary proceedings are filed by or against
                Tenant or any guarantor of this Lease under any bankruptcy,
                insolvency or similar laws and, in the case of any involuntary
                proceedings, are not dismissed within sixty (60) days after
                filing.

Notwithstanding any of the foregoing provisions of this Section 16(A) to the
contrary, no notice of the opportunity to cure a failure to perform or observe
any covenant or obligation of Tenant set forth in thi-s Lease need be given, and
no cure period whatsoever with respect thereto shall be allowed to Tenant, if
the failure to perform or observe is incurable.

     B.   Right of Re-Entry.  Upon the occurrence of a Default, Landlord may
          -----------------
elect to terminate this Lease, or, without terminating this Lease, terminate
Tenant's right to possession of all or any portion of the Premises, in either
case by written notice thereof to Tenant. Upon any such termination, Tenant
shall immediately surrender and vacate the Premises and deliver possession
thereof to Landlord. Tenant grants to Landlord the right, without notice to
Tenant, to enter and repossess the Premises and to expel Tenant and any others
who may be occupying the Premises and to remove any and all property therefrom,
without being deemed in any manner guilty of trespass and without relinquishing
Landlord's rights to Rent or any other right given to Landlord hereunder or by
operation of law.

     C.   Reletting.  If Landlord terminates Tenant's right to possession of the
          ---------
Premises without terminating this Lease, Landlord may relet the Premises or any
part thereof In such case, Landlord shall use reasonable efforts to relet the
Premises on such terms as Landlord shall reasonably deem appropriate; provided,
however, Landlord may first lease Landlord's other available space and shall not
be required to accept any tenant offered by Tenant or to observe any
instructions given by Tenant about such reletting. Tenant shall reimburse
Landlord for the costs and expenses of reletting the Premises including, but not
limited to, all brokerage, advertising, legal, alteration and other expenses
incurred to secure a nov; tenant for the Premises. In addition, if the
consideration collected by Landlord upon any such reletting, after payment of
the expenses of reletting the Premises which have not been reimbursed by Tenant,
is insufficient to pay monthly the full amount of the Rent, Tenant shall pay to
Landlord the amount of each monthly deficiency as it becomes due. If such
consideration is greater than the amount necessary to pay the full amount of the
Rent, the full amount of such excess shall be retained by Landlord and shall in
no event be payable to Tenant.

                                     -18-
<PAGE>

     D.   Termination of Lease.  If Landlord terminates this Lease pursuant to
          --------------------
the terms and provisions of this Section 16, Landlord may recover from Tenant
and Tenant shall pay to Landlord, on demand, the Rent and other charges payable
by Tenant to Landlord through the date of termination, and, in addition, shall
pay to Landlord as damages, at the election of Landlord, either: (x) an
accelerated lump sum amount equal to the present value (calculated using a
discount rate equal to Landlord's reasonable estimate of the yield, as of the
date of termination, produced by United States Treasury general obligation bills
or notes (as the case may be) maturing on the date nearest in time to the
Expiration Date) of the amount by which Landlord's reasonable estimate of the
aggregate amount of Rent owing from the date of such termination through the
Expiration Date plus Landlord's reasonable estimate of the aggregate expenses of
reletting the Premises exceeds Landlord's reasonable estimate of the fair rental
value of the Premises for the same period (after deducting from such fair rental
value the time needed to relet the Premises and the amount of concessions which
would normally be given to a new tenant); or (y) amounts equal to the Rent which
would have been payable by Tenant had this Lease not been so terminated, payable
upon the due dates therefor specified herein following such termination and
until the Expiration Date; provided, however, if Landlord shall re-let the
Premises during such period, then Landlord shall credit Tenant with the net
rents received by Landlord from such re-letting, such net rents to be determined
by first deducting from the gross rents as and when received by Landlord from
such re-letting the expenses incurred or paid by Landlord in tenninating this
Lease, as well as the expenses of re-letting, including altering and preparing
the Premises for new tenants, brokerage commissions, and all other similar and
dissimilar expenses properly chargeable against the Premises and the rental
therefrom, it being understood that any such re-letting rday be for a period
equal to or shorter or longer than the remaining Tenn of this Lease; and
provided, further, that (i) in no event shall Tenant be entitled to receive any
excess of such net rents over the sums payable by Tenant to Landlord hereunder
and (ii) in no event shall Tenant be entitled in any suit for the collection of
damages pursuant to this subparagraph or to a credit in respect of any net rents
from a re-letting except to the extent that such net rents are actually received
by Landlord prior to the commencement of such suit. If the Premises or any part
thereof shall be re-let in combination with other space, a proper apportionment
on a square foot area basis shall be made of the rent received from re-letting
and other expenses of such reletting.

Suit or suits for the recovery of such damages, or any installments thereof, may
be brought by Landlord 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.

     E.   Other Remedies.  At Landlord's election, and notwithstanding any
          --------------
subsequent or intervening cure thereof, Tenant's Default shall excuse Landlord
from its obligations to deliver the Phase II or Phase III Premises to Tenant
and/or to make any advance of funds to Tenant under the Work Letter, provided,
however, that if Landlord shall elect to exercise either such remedy, Landlord
shall be deemed to have elected to terminate the Lease as provided in Section
16(D) hereof. Further, Landlord may but shall not be obligated to perfonn any
obligation of Tenant under this Lease; and, if Landlord so elects, all costs and
expenses paid by Landlord in performing such obligation, together with interest
at the Default.Rate, shall be reimbursed by Tenant to Landlord on demand. Any
and all remedies set forth in this Lease: (i) shall be in addition to any and
all other remedies Landlord may have at law or in equity, (ii) shall be
cumulative, and (iii) may be pursued successively or concurrently as Landlord
may elect. The exercise of any remedy by Landlord shall not be deemed an
election of remedies or preclude Landlord from exercising any other remedies in
the future.

                                     -19-
<PAGE>

     F.   Bankruptcy.  If Tenant becomes bankrupt, the bankruptcy trustee shall
          ----------
not have the right to assume or assign this Leunless the trustee complies
with all requirements of the United States Bankruptcy Code; and Landlord
expressly reserves all of its rights, claims, and remedies thereunder.

     G.   Waiver of Trial by Jury.  Landlord and Tenant waive trial by jury in
          -----------------------
the event of any action, proceeding or counterclaim brought by either Landlord
or Tenant against the other in connection with this Lease.

     17.  HOLDING OVER. If Tenant retains possession of the Premises after the
expiration or earlier termination of the Term or Tenant's right to possession of
the Premises, Tenant shall pay Rent during such holding over at the greater of
(i) two hundred percent (200%) of the fair market rental value of the Premises
or (ii) two and one-quarter times the rate of Rent in effect immediately
preceding such holding over computed on a monthly basis for each month or
partial month that Tenant remains in possession. Tenant shall also pay,
indemnify and defend Landlord from and against all claims and damages,
consequential as well as direct, sustained by reason of Tenant's holding over.
In addition, at any time while Tenant remains in possession, Landlord may elect
instead, by written notice to Tenant and not otherwise, to have such retention
of possession constitute a renewal of this Lease for one (1) year for the fair
market rental value of the Premises as reasonably determined by Landlord but in
no event less than the Rent payable immediately prior to such holding over. The
provisions of this Section do not waive Landlord's right of re-entry or right to
regain possession by actions at law or in equity or any other rights hereunder,
and any receipt of payment by Landlord shall not be deemed a consent by Landlord
to Tenant's remaining in possession or be construed as creating or renewing any
lease or right of tenancy between Landlord and Tenant.

     18.  ESTOPPEL CERTIFICATES.

     A.   Tenant agrees that, from time to time upon not less than ten (10)
business days' prior request by Landlord, Tenant shall execute and deliver to
Landlord a written certificate certifying: (a) that this Lease is unmodified and
in full force and effect (or if there have been modifications, a description of
such modifications and that this Lease as modified is in full force and effect);
(b) the dates to which Rent has been paid; (c) that Tenant is in possession of
the Premises, if that is the case; (d) that Landlord is not in default under
this Lease, or, if Tenant believes Landlord is in default, the nature thereof in
detail; (e) that Tenant has no off-sets or defenses to the performance of its
obligations under this Lease (or if Tenant believes there are any off-sets or
defenses, a full and complete explanation thereof); and (f) such additional
matters as may be requested by Landlord, it being agreed that such certificate
may be relied upon by any prospective purchaser, mortgagee or other person
having or acquiring an interest in the Building. If Tenant fails to execute and
deliver any such certificate within ten (10) business days after request, Tenant
shall be deemed to be in Default of its obligations under the Lease and Landlord
shall have the remedies provided hereunder and at law and in equity for such
Default.

     B.   Landlord agrees that, upon not less than thirty (30) days prior
request by Tenant, and no more than once every twelve (12) months, Landlord
shall execute and deliver to Tenant a certificate providing the certifications
set forth in clauses (a)-(e) above (adjusted as applicable to Landlord),
provided, however, that such certifications shall be qualified to Landlord's
--------
knowledge and belief, and in no event shall Landlord be estopped or barred from
asserting facts contrary to such certifications in any proceeding (including,
without limitation, in any litigation involving this Lease, Tenant or any
successor to Tenant's interest under this Lease) so long as such contrary facts
are based on circumstances first arising after the date of the certification or
circumstances which were concealed from Landlord by Tenant,.

                                     -20-
<PAGE>

     19.  SUBORDINATION. This Lease is and shall be expressly subject and
subordinate at all times to (a) any present or future ground, underlying or
operating lease of the Building, and all amendments, renewals and modifications
to any such lease, and (b) the lien of any present or future mortgage or deed of
trust encumbering fee title to the Building and/or the leasehold estate under
any such lease. If any such mortgage or deed of trust shall be foreclosed, or if
any such lease shall be terminated, the mortgagee, beneficiary or lessor, as the
case may be, shall recognize the Tenant's interest in the Lease and the Tenant
shall attorn to the purchaser at the foreclosure sale or to the lessor under
such lease, subject to and in accordance with the terms of this Lease. Any such
purchaser or lessor, shall not be: (i) subject to any credits, offsets,
defenses, claims," counterclaims or demands that Tenant might have against any
prior landlord (including, without limitation, Landlord); (ii) bound by any
previous modification or amendment of the Lease or by any rent or additional
rent that Tenant might have paid for more than the current month to any prior
landlord, unless such modification or prepayment shall have been made with the
prior written consent of the mortgagee, purchaser (after such purchaser has
succeeded to the interest of the mortgagee or landlord) or lessor, as
applicable; (iii) liable for any accrued obligation, act or omission of any
prior landlord (including, without limitation, Landlord), whether prior to or
after foreclosure or termination of the superior lease, as the case may be; (iv)
bound by any covenant to undertake or complete any improvements to the Building
or the Premises, or to reimburse or pay Tenant for the cost of any such
improvement; (v) required to perform or provide any services not related to
possession or quiet enjoyment of the Premises; or (vi) required to account for
any security deposit other than any security deposit actually delivered to such
successor.

The foregoing provisions are declared to be self-operative and no further
instruments shall be required to effect such subordination and/or attornment;
provided, however, that upon Tenant's request Landlord shall request from any
such mortgagee, beneficiary or lessor (and Tenant, upon the request of any such
mortgagee, beneficiary, lessor or purchaser at foreclosure, as the case may be,
agrees to execute) such subordination and/or attornment instruments as may be
required by such person to confirm such subordination and/or attornment on the
form customarily used by such party. Notwithstanding the foregoing to the
contrary, any such mortgagee, beneficiary or lessor may elect to give the rights
and interests of Tenant under this Lease (excluding rights in and to insurance
proceeds and condemnation awards) priority over the lien of its mortgage or deed
of trust or the estate of its lease, as the case may be. In the event of such
election and upon the mortgagee, beneficiary or lessor notifying Tenant of such
election, the rights and interests of Tenant shall be deemed superior to and to
have priority over the lien of said mortgage or deed of trust or the estate of
such lease, as the case may be, whether this Lease is dated prior to or
subsequent to the date of such mortgage, deed of trust or lease. In such event,
Tenant shall execute and deliver whatever instruments may be required by such
mortgagee, beneficiary or lessor to confirm such superiority on the form
customarily used by such party. If Tenant fails to execute any instrument
required to be executed by Tenant under this Section 19 within ten (10) days
after request, Tenant shall be deemed to be in Default of its obligations under
the Lease and Landlord shall have the remedies provided hereunder and at law and
in equity for such Default.

As long as any mortgage is outstanding, Tenant agrees that Tenant shall not
cancel, surrender, terminate, or enter into any agreement to cancel, surrender
or terminate the Lease, without the prior written approval of such mortgagee. In
the event of any default on the part of Landlord, arising out of or accruing
under the Lease, whereby the validity or the continued existence of the Lease
might be impaired or terminated by Tenant, or Tenant might have a claim for
partial or total eviction or abatement of rent, Tenant shall not pursue any of
its rights with respect to such default or claim, and no notice of termination
of the Lease as a result of such default shall be effective, unless and until
Tenant has given written notice of such default or claim to the applicable

                                     -21-
<PAGE>

mortgage (but not later than the time that Tenant notified Landlord of such
default or claim) and granted to such mortgagee a reasonable time, which shall
not be less than the greater of (i) the period of time granted to Landlord under
the Lease, or (ii) thirty (30) days, after the giving of such notice by Tenant
to such mortgagee, to cure or to undertake the elimination of the basis for such
default or claim, after the time when Landlord shall have become entitled under
the Lease to cure the cause of such default or claim; it being expressly
understood that (a) if such default or claim cannot reasonably be cured within
such cure period, such mortgagee shall have such additional period of time to
cure same as it reasonably determines is necessary, so long as it continues to
pursue such cure with reasonable diligence, and (b) such mortgagee's right to
cure any such default or claim shall not be deemed to create any obligation for
such mortgagee to cure or to undertake the elimination of any such default or
claim.

     20.  QUIET ENJOYMENT. As long as no Default exists, which remains uncured,
Tenant shall peacefully and quietly have and enjoy the Premises for the Tenn,
free from interference by Landlord, subject, however, to the provisions of this
Lease. The loss or reduction of Tenant's light, air or view will not be deemed a
disturbance of Tenant's occupancy of the Premises nor will it affect Tenant's
obligations under this Lease or create any liability of Landlord to Tenant.

     21.  BROKER. Tenant and Landlord each represent (for themselves only) to
the other that they have dealt only with the broker(s) set forth in Item 16 of
the Schedule (the "Broker(s)") in connection with this Lease and that, insofar
as either knows, no other broker negotiated this Lease or is entitled to any
commission in connection herewith. Tenant and Landlord each agree to indemnify,
defend and hold the other, and Landlord's asset manager, its property manager
and their respective employees harmless from and against any claims for a fee or
commission made by any broker, other than the Broker(s), claiming to have acted
by or on behalf of Tenant or Landlord in connection with this Lease. Landlord
shall be responsible for payment of the fees and commissions payable to the
Brokers in connection with this Lease.

     22.  NOTICES. All notices and demands to be given by one party to the other
party under this Lease shall be given in writing, mailed or delivered to
Landlord or Tenant, as the case may be, at the address of each party set forth
in the Schedule or at such other address as either party may hereafter
designate. Notices shall be delivered by hand or by United States certified or
registered mail, postage prepaid, return receipt requested, or by a nationally
recognized overnight air courier service. Notices shall be considered to have
been given upon the earlier to occur of actual receipt or refusal to accept
delivery thereof.

     23.  PARKING. During the Term, Tenant shall be permitted to use at no cost
to Tenant its allocable share of vehicular parking spaces in the parking areas
designated by Landlord for use by Building tenants, subject to such reasonable
terms, conditions and regulations as are from time to time applicable to
authorized users of such parking areas. Tenant's allocable share of such parking
spaces shall be 3.5 parking spaces per 1,000 square feet of rentable floor area
within the Premises, i.e. two hundred fifty-four (254) parking spaces. Such
parking spaces shall be available for Tenant's use on an unassigned, non-
reserved basis. So long as Landlord elects to make available to tenants of the
Building, as matter of management practice, space in the Landlord's 300-space
garage at the Property, Tenant shall have the option on a first-come, first-
served basis to convert one unassigned parking space per 4,000 square feet of
rentable space of the Premises (i.e., up to 18 spaces) to an unassigned space
available in the garage for which Tenant shall pay Landlord's prevailing monthly
rates. Landlord may, pursuant to Section 6 hereof, establish reasonable rules
and regulations regarding Tenant's use of such parking

                                     -22-
<PAGE>

areas. Landlord represents that, as of the date of this Lease, eighteen (18)
spaces are available for Tenant's use in said garage.

     24.  COOPERATIVE INTERRUPTIBLE SERVICE AGREEMENT. Landlord has entered into
that certain Cooperative Interruptible Service Agreement dated March 21, 1994
with Massachusetts Electric Company. If Landlord shall be required to pay a
penalty or extra fee under such Cooperative Interruptible Service Agreement
because of Landlord's election not to allow interruption of electrical service
to the Building after request thereof by Massachusetts Electric Company, Tenant
shall reimburse Landlord for Tenant's Proportionate Share of the amount of such
penalty or extra fee. Such reimbursement shall be made by Tenant to Landlord
within thirty (30) days of receipt by Tenant of a statement setting forth the
total amount of the penalty or extra fee and Tenant's Proportionate Share
thereof.

     25.  SECURITY DEPOSIT. The security deposit set forth in Item 15 of the
Schedule (the "Security Deposit"), shall be deposited and maintained with
Landlord as follows: (a) upon full execution hereof Tenant shall deliver a
letter of credit in the amount of $500,000, drawable on a national bank
headquartered in Boston, Massachusetts and in all other respects acceptable to
Landlord (the "LC"); (b) in the event Tenant shall elect to receive any Tenant
Improvement Advance from Landlord, Tenant shall, on January 1, 2000, and again,
on September 1, 2000 (if additional Tenant Improvement Advances have been made),
cause the amount of the LC to be increased to an amount equal to (i) $500,000,
plus (ii) the amount of all such Tenant Improvement Advance amounts advanced to
Tenant prior to such date, and (c) so long as no Default has occurred under the
Lease, Tenant shall be entitled to reduce the amount of the Security Deposit
evidenced by the LC by $100,000 per year, beginning on September 1, 2001, and on
each anniversary thereof, until the face amount of the LC equals $100,000. In no
event shall the amount of the Security Deposit be reduced below $100,000.

     The Security Deposit is security for the performance of Tenant's
obligations under this Lease. Upon the occurrence of a Default, Landlord may use
all or any part of the Security Deposit for the payment of any Rent or for the
payment of any amount which Landlord may pay or become obligated to pay by
reason of such Default, or to compensate Landlord for any loss or damage which
Landlord may suffer by reason of such Default. If any portion of the Security
Deposit is used, Tenant shall within five (5) days after written demand therefor
deposit cash with Landlord in an amount sufficient to restore the Security
Deposit to its original amount. Landlord shall not be required to keep the
Security Deposit separate from its general funds, and Tenant shall not be
entitled to interest on the Security Deposit. In no event shall the Security
Deposit be considered an advanced payment of Rent, and in no event shall Tenant
be entitled to use the Security Deposit for the payment of Rent. If no default
by Tenant exists hereunder, the Security Deposit or any balance thereof shall be
returned to Tenant within thirty (30) days after the expiration of the Term and
vacation of the Premises by Tenant. Landlord shall have the right to transfer
the Security Deposit to any purchaser of the Building. Upon such transfer,
Tenant shall look solely to such purchaser for return of the Security Deposit;
and Landlord shall be relieved of any liability with respect to the Security
Deposit.

     26.  DIRECTORY; SIGNS. Landlord will place Tenant's i name and suite number
on the Building standard directory. Except for signs which are located wholly
within the interior of the Premises and which are not visible from the exterior
of the Premises, no signs shall be placed, erected, maintained or painted by
Tenant at any place upon the Premises or the Property, except with Landlord's
prior written approval, which approval shall not be unreasonably withheld or
delayed.

                                     -23-
<PAGE>

     27.  RENEWAL OPTION

     A.   Provided Tenant is not in default under this Lease beyond applicable
cure or grace periods and no event or condition exists which with notice and the
expiration of any grace period would constitute a default under this Lease at
the time the option may be exercised, and provided Tenant will be occupying all
of the Premises on the commencement date of the applicable Renewal Tenn (as
hereinafter defined), Landlord grants Tenant one (1) option (the "Renewal
Option") to renew this Lease with respect to all of the Premises for one (1)
additional period of five (5) years (the "Renewal Term"). The Renewal Option may
be exercised by Tenant delivering written notice to Landlord at least twelve
(12) months, but no earlier than fifteen (15) months, prior to the expiration
date of the Term. Time is of the essence in the exercise of the Renewal Option.

     B.   The Base Rent payable for the Renewal Term shall be one hundred
percent (100%) percent of the market rental rate being charged by landlords to
tenants renewing their leases in similarly dernised and improved premises in
Class A office buildings of similar size and quality, offering a similar amenity
package. Within thirty (30) business days after Tenant's exercise of the Renewal
Option, if exercised, Landlord shall notify Tenant in writing of the proposed
Base Rent for the Renewal Term (the "Renewal Rental Rate") as determined by the
above formula. Tenant shall have fifteen (15) business days from the receipt of
Landlord's notice to either accept or dispute Landlord's determination of the
Renewal Rental Rate. In the event that Tenant disputes Landlord's determination,
Tenant shall so notify Landlord and advise Landlord of Tenant's determination of
the Renewal Rental Rate for the applicable Renewal Term as determined by the
above formula. If Landlord and Tenant cannot agree upon the market rental rate
within fifty (50) days of Tenant's original notice of its intent to exercise its
Renewal Option, the following dispute resolution mechanism shall be utilized:
The parties, within ten (10) days after the expiration of said fifty (50) day
period, shall jointly appoint as arbitrator, a certified commercial real estate
appraiser with a minimum of ten (10) years experience in the applicable market.
If Landlord and Tenant cannot agree on an acceptable arbitrator, Landlord and
Tenant shall each choose, within an additional ten (10) days thereafter, its own
arbitrator who meets the qualifications described above. The arbitrators shall
then jointly select, within an additional ten (10) days, an arbitrator to serve
as the arbitrator hereunder. Within fifteen (15) days after appointment, the
arbitrator shall choose either Landlord's or Tenant's determination of market
rental rate. The cost of the arbitrator(s) shall bome equally by Landlord and
Tenant.

     C.   Landlord and Tenant shall execute an amendment to this Lease within
thirty (30) days after the determination of the market rental rate for the
Renewal Term, which amendment shall set forth th& Renewal Term, the annual Base
Rent and all other terms and conditions for the Renewal Term.

     D.   Except as set forth above, the Renewal Term shall be subject to all of
the terms and conditions of this Lease; provided, h6wever, that there shall be
no extension rights at the expiration of the Renewal Tenn.

     28.  TELECOMMUNICATIONS EQUIPMENT.

     Landlord hereby grants to Tenant a non-exclusive license to use a portion
of the roof of Tower III of the Building (to be determined by Landlord) for
installation and use of one satellite or wireless antenna (the "Communication
Equipment") during the Term of the Lease. Landlord shall have the unrestrained
right to approve the location, size, and installation of the Communication
Equipment to ensure the same does not (a) interfere with or compromise the
rights or operation of equipment of any other tenant or licensee of space on the
roof, or (b) present any risk of damage to such equipment, the roof, roof
membrane, or the structure of the roof and/or the Building. Tenant shall have no
obligation to pay rent for such license, but Tenant shall, at its sole cost

                                     -24-
<PAGE>

and expense, maintain such Communication Equipment in good condition and repair,
and comply with the terms and conditions set forth herein and in Exhibit F
hereto for use of the Communication Equipment and the roof and the building
structure. Unless Landlord's prior written consent has been obtained, said
license may not be transferred or assigned by Tenant to any party (other than a
party to which Tenant's rights under this Lease have been Transferred and with
respect to which Landlord's consent is either not required or has been obtained
pursuant to Section 14 of this Lease).

     29.  MISCELLANEOUS.

     A.   Successors and Assigns.  Subject to Section 14 of this Lease, each
          ----------------------
provision of this Lease shall extend to, bind and inure to the benefit of
Landlord and Tenant and their respective legal representatives, successors and
assigns; and all references herein to Landlord and Tenant shall be deemed to
include all such parties.

     B.   Entire Agreement.  This Lease, and the riders and exhibits, if any,
          ----------------
attached hereto which are hereby made a part of this Lease, represent the
complete agreement between Landlord and Tenant; and Landlord has made no
representations or warranties except as expressly set forth in this Lease. No
modification or amendment of or waiver under this Lease shall be binding upon
Landlord or Tenant unless in writing signed by Landlord and Tenant.

     C.   Time of Essence.  Time is of the essence of this Lease and each and
          ---------------
all of its provisions.

     D.   Execution and Delivery.  Submission of this instrument for examination
          ----------------------
or signature by Tenant does not constitute a reservation of space or an option
for lease, and it is not effective until execution and delivery by both Landlord
and Tenant. Execution and delivery of this Lease by Tenant to Lmdlord shall
constitute an irrevocable offer by Tenant to lease the Premises on the terms and
conditions set forth herein, which offer may not be revoked for five (5)
business days after such delivery.

     E.   Severability. The invalidity or unenforceability of any provision of
          ------------
this Lease shall not affect or impair any other provisions of this Lease.

     F.   Governing Law.  This Lease shall be governed by and construed in
          -------------
accordance with the laws of The Commonwealth of Massachusetts.

     G.   Attorneys' Fees.  Tenant shall pay to Landlord all costs and expenses,
          ---------------
including reasonable attorneys fees, incurred by Landlord in enforcing this
Lease or incurred by Landlord as a result of any litigation to which Landlord
becomes a party as a result of this Lease.

     H.   Joint and Several Liability.  If Tenant is comprised of more than one
          ---------------------------
party, each such party shall be jointly and severally liable for Tenant's
obligations under this Lease.

     I.   Force Majeure.  Landlord shall not be in default hereunder and Tenant
          -------------
shall not be excused from performing any of its obligations hereunder if
Landlord is prevented from performing any of its obligations hereunder due to
any accident, breakage, strike, shortage of materials, acts of God or other
causes beyond Landlord's reasonable control.

                                     -25-
<PAGE>

     J.   Captions.  The headings and titles in this Lease are for convenience
          --------
only and shall have no effect upon the construction or interpretation of this
Lease.

     K.   No Waiver.  No receipt of money by Landlord from Tenant after
          ---------
termination of this Lease or after the service of any notice or after the
commencing of any suit or after final judgment for possession of the Premises
shall renew, reinstate, continue or extend the Term or affect any such notice or
suit. No waiver of any default of Tenant shall be implied from any omission by
Landlord to take any action on account of such default if such default persists
or be repeated, and no express waiver shall affect any default other than the
default specified in the express waiver and then only for the time and to the
extent therein stated.

     L.   No Recording.  Tenant shall not record this Lease. Landlord and
          ------------
Tenant shall, upon request of either, execute and deliver a notice of this Lease
in such recordable form as may be permitted by applicable law.

     M.   Definition of Landlord; Landlord's Liabilily.  The word "Landlord" is
          --------------------------------------------
used herein to include the Landlord named above as well as its successors and
assigns, each of whom shall have the same rights, remedies, powers, authorities
and privileges as it would have had it originally signed this Lease as Landlord.
Any such person, whether or not named herein, shall have no liability hereunder
after it ceases to hold title to the Premises except for obligations which may
have theretofore accrued. Neither Landlord nor any principal, employee or
partner of Landlord nor any owner of the Property, whether disclosed or
undisclosed, shall have any personal liability with respect to any of the
provisions of this Lease or the Premises, and neither Landlord nor any
principal, employee or partner of Landlord shall have any personal liability to
Tenant for any liability of,or claim against Landlord under this Lease beyond
the equity of the Landlord in the Building and the Fee Land.

     N.   Financial Reports.  Within fifteen (15) days after Landlord's request
          -----------------
therefor, Tenant shall furnish to Landlord Tenant's most recent audited
financial statements (including any notes to them) or, if no such audited
statements have been prepared, such other financial statements (and notes to
them) as may have been prepared by an independent certified public accountant
or, failing those, Tenant's internally prepared financial statements. Tenant
shall discuss its financial statements with Landlord and Tenant shall reasonably
provide components of its books and records in order to enable Landlord to
verify the financial statements. Landlord will not disclose any aspect of
Tenant's financial statements that Tenant designates to Landlord as confidential
except (i) to Landlord's lenders or prospective purchasers of the Property or
any portion thereof, (ii) in litigation between Landlord and Tenant, and (iii)
if required by court order.

     O.   Telecommunications.  Tenant and its telecommunications companies,
          ------------------
including but not limited to local exchange telecommunications companies and
alternative access vendor services companies, shall have no right of access to
and within the Building for the installation and operation of telecommunications
systems, including but not limited to voice, video, data, and any other
telecommunications services provided over wire, fiber optic, microwave,
wireless, and any other transmission systems, for part or all of Tenant's
telecommunications within the Building and from the Building to any other
location without Landlord's prior written consent, the withholding of which
shall not be patently unreasonable.

     P.   Landlord's Representations.  Landlord is the owner of the Property,
          --------------------------
and Landlord has full right, power, and authority to enter into this Lease. To
Landlord's knowledge, as of the date hereof, the Building, its structure, roof,
and mechanical, electrical and HVAC building systems are in good operating
condition; the smoke alarms and life safety systems in the Building are in good
working order and comply with all state and

                                     -26-
<PAGE>

local fire and safety code requirements applicable thereto; the Building common
areas are in compliance with all requirements of the ADA.

     IN WITNESS WHEREOF, Landlord and Tenant have executed this Lease as a
scaled instrument as of the day and year first above written.

WITNESS:                           LANDLORD:

                                   CROSS POINT LIMITED PARTNERSHIP, a
                                   Massachusetts limited partnership

                                        By: YBCP, L.L.C., its general partner

                                            By: BRE/Cross Point LLC, a member

________________________                    By: ________________________
Name:                                           Name:
                                                Title:

WITNESS:                           TENANT:

                                   CONVERGENT NETWORKS, INC., a Delaware
                                   corporation

________________________           By: _________________________________
Name:                                    Name:
                                         Title: President (or Vice President)

________________________           By: _________________________________
Name:                                    Name:
                                         Title: Treasurer (or Assistant
                                         Treasurer)

                                     -27-
<PAGE>

                                   EXHIBIT A
                                   ---------

                         LEGAL DESCRIPTION OF FEE LAND
                         -----------------------------

Three (3) certain parcels of land located in Lowell and in Chelmsford in
Middlesex County, Massachusetts, more particularly described as Parcel 1, Parcel
2, and Parcel 3, below:

Parcel 1:
--------

A certain parcel of land situated southwest of Industrial Avenue at River Meadow
Brook in the City of Lowell, County of Middlesex, Commonwealth of Massachusetts,
bounded and described as follows:

Beginning at a point on the southwesterly side of Industrial Avenue and the
northeasterly comer of said lot thence;

S 59-05'36"E   A distance of sixty-four and forty-seven hundredths feet (64.47')
               to a point; thence

S 46-22'30"W   A distance of six hundred twenty-eight and eighty three
               hundredths feet (628.83') to a point; thence

S 56-26'20"W   A distance of three hundred ninety and twenty-five hundredths
               feet (390.25') to a point; thence

N 17-55'20"W   A distance of one hundred thirty and no hundredths feet (130.00')
               to a point; thence

N 56-03'05"E   A distance of four hundred eighty-eight and fifty-four hundredths
               feet (488.54') to a point; thence

Northeasterly  And curving left along the arc of a curve having a radius of two
               thousand eight hundred ninety-seven and ninety three hundredths
               feet (2897.93'), a length of four hundred sixty and twenty-four
               hundredths feet (460.24') to the point of beginning on the
               southwesterly side of Industrial Avenue.

The above described parcel of land contains 2.276 acres in the City of Lowell,
Massachusetts and is shown as Lot 2 on a plan entitled "Subdivision Plan of Land
in Lowell, Massachusetts" by Vanasse Hangen Brustlin, Inc., scale 1" = 80',
dated February 27, 1995 and revised May 22, 1995, which plan is recorded with
the Middlesex North District Registry of Deeds with the below-described deed.

For title to Parcel 1, see deed recorded with the Middlesex North District
Registry of Deeds in Book 7158, Page 147.

Parcel 2:
--------

A certain parcel of land with the buildings thereon situated partly in Lowell
and partly in Chelmsford, Middlesex County, Massachusetts, and bounded and
described as follows:

Beginning at a point located 165.08 feet on a curve to the right having a radius
of 4,750.00 feet from Sta. 1285+02.50 located on centerline of location, Lowell
Secondary Branch, Boston and Maine Corporation, thence running on a curve to the
left a distance of 198.85 feet to a point; thence turning and running

                                     A - 1
<PAGE>

North 57- 09' 30" East, 1,417.96 feet to a point; thence turning and running

On a curve to the left having a radius of 2,831.93 feet a distance of 466.97
feet to a point; thence turning and running

South 57- 5 8' 11 " East 44.54 feet to a point; thence turning and running

South. 46- 56' 05" West 35.74 feet to a point; thence turning and running

South 57- 5 8' 11 " East 23.45 feet to a point; thence turning and running

On a curve to t1he right having a radius of 2,897.93 feet a distance of 460.49
feet to a point; thence turning and running

South 57- 09' 30" West 982.69 feet to a point; thence turning and running

South 49. 27' 00" East 8.65 feet to a point; thence turning and running

South 43- 17' 30" West 600.00 feet to the point of beginning.

Be all of said measurements, more or less, however otherwise bounded and
described, said parcel containing an area of 2.125 acres in the Town of
Chelmsford and 1.452 acres in the City of Lowell, or a total of 3.577 acres,
more or less, and being shown upon plan marked: "Plan of Land in Lowell &
Chelmsford, Massachusetts, Robert W. Meserve, et al, Trustees of the Property of
the Boston and Maine Corporation to Wang Laboratories, Inc., Scale: I" = 60',
August 19, 1980, Dana F. Perkins and Assoc., Inc., Civil Engineers and
Surveyors, Reading -Lowell, Mass." recorded with the Middlesex North District
Registry of Deeds in Plan Book 134, Page 70.

For title to Parcel 2, see deed recorded with the Middlesex North District
Registry of Deeds in Book 7158, Page 147.

Parcel 3:
--------

A certain parcel of land with the buildings thereon, situate partly in Lowell
and partly in Chelmsford in the County of Middlesex, Commonwealth of
Massachusetts, bounded and described as follows:

Northwesterly by Chelmsford Street, seven hundred sixty-one and 07/100 (761.07)
feet;

Northerly by the southerly line forming the junction of said Chelmsford Street
and Industrial Avenue, one hundred one and 41/100 (101.41) feet;

Northeasterly by the southwesterly line of said Industrial Avenue, eight hundred
ninety and 19/100 (890.19) feet;

Southeasterly by land now or formerly of Trustees of the New York, New Haven and
Hartford Railroad Company Debtor, twelve hundred ninety-three and 24/100
(1293.24) feet; and

Westerly eleven and 12/100 (11.12) feet;

Northwesterly three hundred twenty-four and 83/100 (324.83) feet;

Northerly eleven and 06/100 (11.06) feet;

                                     A - 2
<PAGE>

Northwesterly one hundred eighty-six and 60/100 (186-60) feet; and

Southwesterly two hundred sixteen (216) feet by land now for formerly of
Massachusetts Electric Company.

All of the boundaries are determined by the Land Court to be located as shown on
Plan 33375-A, drawn by Dana F. Perkins & Sons Inc., Surveyors, dated July 6,
1964 and October 1965, as modified and approved by the Court, filed in the Land
Registration Office, a copy of a portion of which is filed with Certificate of
Title No. 14864.

For title to Parcel 3, see Certificate of Title No. 31319 filed with the
Middlesex North Registry District of the Land Court in Registration Book 159,
Page 237.

                                     A - 3
<PAGE>

                                  EXHIBIT A-1
                                  -----------

                      LEGAL DESCRIPTION OF EASEMENT LAND
                      ----------------------------------

A certain parcel of land situated at the southwesterly intersection of
Industrial Avenue and River Meadow Brook in the City. of Lowell, County of
Middlesex, Commonwealth of Massachusetts, bounded and described as follows:

Beginning at the point at the northwesterly comer of the intersection of
Industrial Avenue and a private way known as Reiss Avenue; thence

S 44-05'16"E   A distance of fifty and no hundredths feet (50.00') to a point,
               by said Industrial Avenue; thence

S 45-54'44"W   A distance of fifty and no hundredths feet (50.00') to a point;
               thence

S 44-05'16"E   A distance of eighty-seven and sixty five hundredths feet
               (87.65') to a point; thence

S 10-54'44"W   A distance of two hundred seven and ninety hundredths feet
               (207.90') to a point; thence

N 82-54'42"E   A distance of two hundred seventy five and fifty hundredths feet
               (275.50') to a point, the last four (4) courses by land now or
               formerly of Shaw Corp; thence

S 07-05'18"E   A distance of one hundred forty-two and twenty-nine hundredths
               feet (142.29') to a point; thence

S 00-24'42"W   A distance of four hundred sixty-seven and fifteen hundredths
               feet (467.15') to a point of non-tangency; thence

Southwesterly  And curving to the right along the are of a curve having a radius
               of one thousand nine hundred twenty and no hundredths feet
               (1,920.00') a length of three hundred and fifty-five hundredths
               feet (300.55') to a point; thence

Southwesterly  And curving to the right along the arc of a curve having a radius
               of seven hundred twenty and no hundredths feet (720.00') a length
               of two hundred seventy-nine and ninety-four hundredths feet
               (279.94') to a point; thence

Northwesterly  And curving to the right along the arc of a curve having a radius
               of two hundred forty and no hundredths feet (240.00'), a length
               of three hundred ten and twenty-nine hundredths feet (310.29') to
               a point; thence

N 71-38'56"W   A distance of five hundred twenty-seven and seventeen hundredths
               feet (527.17') to a point; thence

Northwesterly  And curving to the right along the arc of a curve having a radius
               of two thousand nine hundred twenty and no hundredths feet
               (2,920.00'), a length of sixty three and twenty-one hundredths
               feet (63.2l') to a point, the last seven (7) courses by the State
               Highway layout #4709 of both the Lowell Connector and Route 495;
               thence

                                     A - 4
<PAGE>

N 17-55'20"W   A distance of seven hundred fifty-eight and thirty-nine
               hundredths feet (758.39') to a point; thence

N42-12'04"E    A distance of one hundred seventy-three and two hundredths feet
               (173.02') to a point; thence

N17-55'20"W    A distance of four hundred sixty-four and forty-eight hundredths
               feet (464.48') to a point, the last three (3) courses by land now
               or formerly of New England Power Co. and the Town Line; thence

N56-26'20"E    A distance of three hundred ninety and twenty-five hundredths
               feet (390.25') to a point; thence

N46-22'30"E    A distance of six hundred twenty-eight and eighty-three
               hundredths feet (628.83') to a point, the last two (2) courses by
               Lot 2; thence

S 59-05'36"E   A distance of one hundred twenty-four and eight three hundredths
               feet (124.83') to a point; thence

S 44-05'16"E   A distance of one hundred five and thirty-seven hundredths feet
               (105.37') to a point; thence

Southwesterly  And curving to the right along the arc of a curve having a radius
               of ninety-one and no hundredths feet (91.00'), a length of
               twenty-seven and thirty-one hundredths feet (27.3 1') to a point;
               thence

S 00-24'42"W   A distance of three hundred thirty-eight and thirteen hundredths
               feet (338.13') to a point; thence

Southwesterly  And curving to the right along the arc of a curve having a radius
               of ninety-one and no hundredths feet (91.00'), a length of
               seventy-two and twenty-seven hundredths feet (72.27') to the
               point of beginning, the last five (5) courses by the westerly
               sideline of Industrial Avenue.

     The above described parcel of land contains 42.403 acres in the City of
Lowell, Massachusetts and is shown as Lot I on a plan entitled "Subdivision Plan
of Land in Lowell, Massachusetts" by Vanasse Hangen Brustlin, Inc., scale I" =
80', dated February 27, 1995 and revised May 22, 1995, which plan is recorded
with the Middlesex North District Registry of Deeds with the below-referenced
deed.

     The above described parcel of land includes, in addition to land not
registered, the following parcels of registered land: (i) Lot 3 as shown on Land
Court Plan No. 30641B, more particularly described in Certificate of Title No.
22535; and (ii) Lot 6 as shown on Land Court Plan No. 30641 C, more particularly
described in Certificate of Title No. 25059.

     For title reference, see deed of Wang Laboratories, Inc. recorded with the
Middlesex North District Registry of Deeds in Book 7518, Page 140 and filed for
registration with Middlesex North Registry District of the Land Court as
Document No. 159311, and Certificate of Title No. 31999.

                                    A - 5
<PAGE>

                                   EXHIBIT B
                                   ---------

                            FLOOR PLAN OF PREMISES
                            ----------------------

     See attached floor plans for floors 10, 11, and 12 of Tower III of the
Building.

                                     B - 1
<PAGE>

                                   EXHIBIT C
                                   ---------

                                  SKETCH PLAN
                                  -----------

                          [TO BE PROVIDED BY TENANT]

                                     C - 1
<PAGE>

                                   EXHIBIT D
                                   ---------

                                  WORK LETTER
                                  -----------

THIS WORK LETTER AGREEMENT ("Work Letter") is entered into as of the day of
                             -----------
August, 1999 by and between CROSS POINT LIMITED PARTNERSHIP, ("Landlord"), and
                                                               --------
CONVERGENT NETWORKS, INC. ("Tenant").
                            ------

                                   RECITALS
                                   --------

A.   Concurrently with the execution of this Work Letter, Landlord and Tenant
have entered into a certain Lease dated the date hereof (the "Lease") leasing
                                                              -----
72,632 rentable square feet of space on two floors of Tower III of the Building
(the "Premises"), as more particularly described in the Lease. All terms not
      --------
defined herein have the same meaning as set forth in the Lease.

B.   The terms and conditions of this Work Letter shall apply to the design and
construction of alterations to the Premises, which is to be designed and
constructed by Tenant.

C.   In order to induce Landlord to enter into the Lease and in consideration of
the mutual covenants hereinafter contained, Landlord and Tenant agree as
follows:

                                   AGREEMENT
                                   ---------

1.   LANDLORD'S DELIVERY OF THE PREMISES.
     -----------------------------------

     (a)  Landlord agrees to deliver the Premises to Tenant in the following
     condition (the "Base Building Elements") no later than August 15, 1999:
                     ----------------------

          (i)    Landlord's Services (as defined in the Lease) fully installed,
                 available and in good working condition.

          (ii)   Sprinkler risers delivered to the floor; valve connections and
                 main sprinkler service available.

          (iii)  Electrical/telephone closets available.

          (iv)   Primary HVAC ductwork from mechanical equipment room to the
                 Premises.

          (v)    Fire protection alarm system installed.

          (vi)   Life safety systems installed.

          (vii)  Minor items of damage listed on Schedule I hereto having been
                 repaired.

          (viii) Data, electric and phone wiring to the existing cubicles in the
                 same condition as they are as of the date of this Work Letter.

     (b)  Tenant acknowledges that certain furniture and installations (the
     "Workstations") are presently stored in the Premises. The Workstations are
     the property of Steelcase Corporation and were leased by

                                     E - 2
<PAGE>

     the former tenant of the Premises. If Tenant wishes to make use of the
     Workstations during the Lease term, Tenant shall be responsible for making
     any necessary arrangements directly with Steelcase Corporation. If Tenant
     wishes to have the Workstations removed, Tenant shall be responsible for
     making any necessary arrangements directly with Steelcase Corporation.
     Landlord shall cooperate with Tenant in this regard and permit Steelcase
     Corporation or its agents reasonable access to the Premises for purposes of
     removing the Workstations, but Landlord shall have no liability to tenant
     under the Lease or under this Workletter on account of the presence of the
     Workstations in the Premises.

2.   TENANT'S WORK.  As used in the Lease and this Work Letter Agreement, the
     -------------
term "Tenant's Work" means those items of general tenant improvement
      -------------
construction shown on the Final Plans (described in Paragraph 5(b) below). All
Tenant's Work attached to the Premises and components thereof shall at all times
be and remain the sole property of Landlord, excluding Tenant's computer and
telecommunications equipment.

3.   CONSTRUCTION REPRESENTATIVES.  Landlord appoints the following person(s) as
     ----------------------------
Landlord's representative ("Landlord's Representative") to act for Landlord in
                            -------------------------
all matters covered by this Work Letter:

     James E. Lesko III
     Cross Point Limited Partnership
     900 Chelmsford Street
     Lowell, MA 01851

Tenant appoints the following person(s) as Tenant's representative ("Tenant
Representative") to act for Tenant in all matters covered by this Work Letter.

     Karen Vergura
     Convergent Networks, Inc.
     900 Chelmsford Street
     Lowell, MA 01851

All communications with respect to the matters covered by this Work Letter are
to be made to Landlord's Representative or Tenant's Representative, as the case
may be, in writing, in compliance with the notice provisions of the Lease.
Either party may change its representative under this Work Letter at any time by
written notice to the other party in compliance with the notice provisions of
the Lease.

4.   DESIGN AND CONSTRUCTION. All Tenant's Work shall be performed by designers
     -----------------------
("Tenant's Architect") and contractors ("Tenant's Contractor") selected and
  ------------------                     -------------------
engaged by Tenant and approved in advance by Landlord (such approval not to be
unreasonably withheld).

5.   TENANT IMPROVEMENT PLANS.
     ------------------------

     (a)  Preparation of Final Plans.  Tenant's Architect will prepare (i)
          --------------------------
     schematic design drawings (the "Schematics"), (ii) design development
                                     ----------
     drawings (the "Designs"), and (iii) complete architectural plans, drawings
                    -------
     and specifications and complete engineered mechanical, structural and
     electrical working drawings for all of Tenant's Work (the "Final Plans").
                                                                -----------
     The Final Plans will show: (A) the subdivision (including partitions and
     walls), layout, lighting, finish and decoration work (including carpeting
     and other floor coverings) for the Premises; (B) all internal and external
     communications and utility facilities which will require the installation
     of conduits or other improvements from the base Building shell and/or
     within common areas; and (C) all other specifications for Tenant's Work.
     The Schematics, the Designs

                                     E - 3
<PAGE>

     and the Final Plans will each be submitted to Landlord for Landlord's
     approval. Landlord agrees to advise Tenant in writing of any disapproval of
     the Schematics, the Designs or the Final Plans and the reasons therefor
     within five (5) business days of receipt thereof. If Landlord in its
     reasonable discretion does.,not approv'e the Schematics, the Designs or the
     Final Plans, Tenant will then cause Tenant's Architect to redesign the
     Schematics, the Designs or the Final Plans, as applicable, incorporating
     the revisions reasonably requested by Lafidlord so as to make the
     Schematics, the Designs, or Final Plans consistent with Landlord's
     requests.

     (b)  Requirements of the Final Plans.  The Final Plans will include
          -------------------------------
     locations and complete dimensions of the Tenant's Work, and will: (i) be
     compatible with the Building shell and with the design, construction and
     equipment of the Building; (ii) be compatible with and of at least equal
     quality as tenant improvement work generally approved by Landlord; (iii)
     comply with all applicable laws, ordinances, rules and regulations of all
     governmental authorities having jurisdiction, and all applicable insurance
     regulations; (iv) not require Building service beyond the level normally
     provided to other tenants in the Building without Landlord's prior written
     consent, and will not overload the floors of the Building; and (v) be
     generally of a "Class A" nature and quality, as determined by Landlord in
     its reasonable discretion.

     (c)  Submittal of Final Plans. Once the Final Plans have been approved by
          ------------------------
     Landlord, Tenant shall submit the following to Landlord: (i) the Final
     Plans signed and stamped by Tenant's Architect; (ii) an application for a
     building permit, signed by Tenant's Contractor; and (iii) any other
     documents required by the City of Lowell to obtain a building permit
     (collectively the "Application Documents"). Landlord will then co-sign the
                        ---------------------
     application for a building permit and Tenant will submit the Application
     Documents to the appropriate governmental agencies for plan checking and
     the issuance of a building permit. Tenant's Architect will make any changes
     to the Final Plans which are requested by the applicable governmental
     authorities to obtain the building permit but only after receipt of
     Landlord's prior written approval, such approval not to be unreasonably
     withheld.

     (d)  Changes to Shell of Building. Tenant's Work shall in no event require
          ----------------------------
     any structural or any changes in the building shell.

6.   PAYMENT FOR TENANT'S WORK.
     -------------------------

     (a)  Tenant Improvement Allowance, Tenant Improvement Advance and Excess
          -------------------------------------------------------------------
     Costs. Landlord shall pay for Tenant's Work up to a maximum of $363,160
     -----
     ($5.00 per rentable square foot of the entire Premises) (the "Tenant
                                                                   ------
     Improvement Allowance"). If the Tenant Improvement Allowance is exhausted,
     ---------------------
     Landlord shall also advance up to an additional $363,160 in the manner set
     forth in the preceding sentence to pay additional costs of Tenant's Work
     (the "Tenant Improvement Advance"). Tenant must notify Landlord on or prior
           --------------------------
     to July 1, 2000 whether it elects to receive all or any portion of the
     Tenant improvement Advance. Tenant shall repay the Tenant Improvement
     Advance to Landlord, together with interest at the rate of 12% per annum
     thereon, as provided in Section 2(B) of the Lease. The Tenant Improvement
     Allowance and the Tenant Improvement Advance shall only be used for:

          (i)  Payment of plan check, engineering and tech fees, permit and
               license fees relating to construction of Tenant's Work.

          (ii) Payments to Tenant's Contractor for construction of Tenant's
               Work, including, without limitation, the following:

                                     E - 4
<PAGE>

               (A)  Installation within the Premises of all partitioning, doors,
                    floor coverings, ceilings, wall coverings and painting,
                    millwork and similar items;

               (B)  All electrical wiring, lighting fixtures, outlets and
                    switches, and other electrical work to be installed within
                    the Premises;

               (C)  Any additional tenant requirements including, but not
                    limited to, air quality control, special heating,
                    ventilation and air conditioning, noise or vibration control
                    or other special systems;

               (D)  All plumbing, including fixtures and pipes, to be installed
                    within the Premises;

               (E)  Testing and inspection costs; and

               (F)  Contractor's fees, including, but not limited to, any fees
                    based on general conditions.

     (b)  Changes.  If, after the Final Plans have been approved by Landlord,
          -------
     Tenant requests any material changes or substitutions to the Final Plans
     during construction, Tenant shall obtain Landlord's written approval of
     such change in accordance with Paragraph 10 hereof.

     (c)  Payments to Tenant's Contractor.  Tenant's Contractor shall be paid in
          -------------------------------
     monthly installments based upon its submission of customary documentation
     which is of a scope and detail sufficient to satisfy a commercial
     construction lender operating in the market area in which the Property is
     located.

     (d)  Additional Costs.  All costs in excess of the Tenant Improvement
          ----------------
     Allowance and the Tenant Improvement Advance (if elected) ("Excess Costs")
               C                                                 ------------
      shall be paid by Tenant. Tenant shall also pay on demand Landlord's
     customary construction review and supervision fee, which fee shall be equal
     to five percent (5%) of the total hard construction costs payable by Tenant
     for construction of Tenant's Work.. Tenant hereby indemnifies Landlord
     against liability for any mechanics' and other liens filed in connection
     with any Excess Costs for Tenant's Work, including the liens of any chattel
     mortgages, security agreements or financing statements upon any materials
     or fixtures installed in and constituting part of the Premises. Tenant, at
     its expense, shall procure the discharge of all such liens within twenty
     (20) days after the filing of any such lien against the Property or any
     part thereof.

     (e)  No Credit.  Tenant shall not be entitled to a credit for any portion
          ---------
     of the Tenant Improvement Allowance or Tenant Improvement Advance which is
     not used.

7.   CONSTRUCTION OF TENANT'S WORK.  Until Landlord approves the Final Plans and
     -----------------------------
all necessary permits have been obtained from the appropriate governmental
authorities, Tenant's Contractor shall not begin the construction of any of
Tenant's Work. The cost of such work shall be paid as provided in Paragraph 6.
Upon receipt of Landlord's approval of the Final Plans and all necessary permits
as provided above, Tenant and Tenant's Contractor shall commence Tenant's Work
and shall diligently prosecute the same with all reasonable speed to full and
final completion. Tenant shall conduct and attend weekly progress meetings with
Landlord's Representative at the end of each week during construction.

8.   FREIGHT/CONSTRUCTION ELEVATOR.  Landlord will, consistent with its
     -----------------------------
obligation to other tenants in the Building, make the freight/construction
elevator reasonably available to Tenant in connection with

                                     E - 5
<PAGE>

the completion of the Premises and furnishing and moving into the Premises.
Tenant airees to pay for any after-hours staffing of the freight/construction
elevator, if needed.

9.   APPROVALS.  Whenever any party under this Work Letter must reasonably grant
     ---------
its approval such party shall also not unreasonably delay or condition its
approval. Any approval shall be deemed granted unless such party responds within
seven (7) days after its receipt of the items for which approval is sought.

10.  LANDLORD'S APPROVAL.  Landlord, in its sole discretion, may withhold its
     -------------------
approval of the Final Plans, changes to the Final Plans or other documents or
plans that:

     (a)  Exceeds or adversely affects the structural integrity of the Building,
     or any part of the heating, ventilating, air conditioning, plumbing,
     mochanical, electrical, communication, or other systems of the Building;

     (b)  Is not approved by any mortgagee at the time the work is proposed;

     (c)  Would not be approved by a prudent owner of property similar to the
     Building;

     (d)  Violates any agreement which affects the Building or binds the
     Landlord;

     (e)  Landlord believes will increase the cost of operation or maintenance
     of any of the systems of the Building;

     (f)  Does not conform to the applicable building code or is not approved by
     any governmental, quasi-govermnental, or utility authority with
     jurisdiction over the Premises; or

     (g)  Is not compatible with and at least of comparable quality with
     improvements in other tenant spaces in the Building.

11.  TENANT'S CONTRACTOR'S INSURANCE.  During the construction of Tenant's Work,
     -------------------------------
Tenant's Contractor shall carry worker's compensation insurance covering all
persons employed in connection with said construction in statutory limits,
general liability insurance (with completed operations endorsement) for any
occurrence in or about the Premises and Property in which Landlord, Landlord's
agents, and any mortgagee shall be named as parties insured, and any other type
of insurance reasonably required by Landlord, all in such limits as Landlord may
reasonably prescribe, with insurers reasonably satisfactory to Landlord. Tenant
shall furnish Landlord with satisfactory evidence that such insurance is in
effect before the commencement of the construction of Tenant's Work and, on
request, at reasonable intervals thereafter.

12.  INDEMNIFICATION OF LANDLORD.  Tenant indemnifies and holds Landlord, and
     ---------------------------
Landlord's agents and their respective employees, harmless from and against any
and all losses, claims, demands, liabilities, fines, penalties and expenses,
including their respective reasonable attorneys' fees, costs and disbursements,
in any way arising from or related to the construction of Tenant's Work by
Tenant's Contractor, any subcontractors or any other party hired by or through
Tenant or Tenant's Contractor.

13.  DEFAULTS BY TENANT.  In the event of any default by Tenant with respect to
     ------------------
any of the provisions of this Work Letter or any other agreement with Landlord
relating to construction in or about the Premises, which default remains uncured
30 days after receipt of notice thereof from Landlord, Landlord may, in addition
to exercising any other right or remedy Landlord may have, treat such default
as-a Default by Tenant under the

                                     E - 6
<PAGE>

Lease and exercise any or all rights available under the Lease in connection
therewith, including, if applicable, the right of termination. In the event of
any termination of the Lease by Landlord, Landlord may elect in its absolute
discretion, with respect to any work performed by or on behalf of Tenant prior
to the date of such termination, to either:

     (a)  retain for its own use part or all of any such work, without
     compensation to Tenant therefor; or

     (b)  demolish or remove part or all of any such work and restore part or
     all of the Premises to its condition prior to the initial tender of
     possession thereof to Tenant, in which event Tenant shall reimburse
     Landlord upon demand for all costs reasonably incurred by Landlord in
     connection with such demolition, removal and/or restoration.

     IN WITNESS WHEREOF, the undersigned Landlord and Tenant have caused this
Work Letter Agreement to be duly executed by their duly authorized
representatives as of the date of the Lease.

WITNESS:                            LANDLORD:

                                    CROSS POINT LIMITED PARTNERSHIP, a
                                    Massachusetts limited partnership

                                         By: YBCP, L.L.C., its general partner

                                             By: BRE/Cross Point LLC, a member

_____________________                        By: __________________
Name:                                             Name:
                                                  Title:

WITNESS:                            TENANT:

                                    CONVERGENT NETWORKS, INC., a Delaware
                                    corporation

_____________________               By: ___________________________
Name:                                    Name:
                                         Title: President (or Vice President)

_____________________               By: ____________________________
Name:                                    Name:
                                         Title: Treasurer (or Assistant
                                         Treasurer)

                                     E - 7
<PAGE>

                                  SCHEDULE 1
                                  ----------

                           LIST OF REQUIRED REPAIRS
                           ------------------------

                                     D - 8
<PAGE>

                                   EXHIBIT E
                                   ---------

                              LANDLORD'S SERVICES
                              -------------------

I.  CLEANING
    --------

A.  Office Area

    Daily: (Monday through Friday, inclusive, holidays excepted).

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

    2.  Sweep and dust mop all uncarpeted areas using a dust-treated mop.

    3.  Vacuum all rugs and carpeted areas.

    4.  Hand dust and wipe clean with treated cloths all horizontal surfaces
including furniture, office equipment, window sills, door ledges, chair rails,
and convector tops, within reach, but excluding active work areas.

    5.  Wash clean all water fountains.

    6.  Remove and dust under all desk equipment and telephones and replace
same.

    7.  Hand dust all grill work within normal reach.

    8.  Upon completion of cleaning, all lights will be turned off and doors
locked, leaving the Premises in an orderly condition.

    Weekly:

    1.  Dust exposed coat racks and the like.

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

    Quarterly:

    Render high dusting not reached in daily cleaning to include:

    1.  Dusting all pictures, frames, charts, graphs and similar wall hangings.

    2.  Dusting all vertical surfaces, such as walls, partitions, doors and
ducts.

    3.  Dusting of all pipes, ducts, and high moldings.

    4.  Dusting of all horizontal blinds.

                                      E-1
<PAGE>

B.  Lavatories

    Daily:  (Monday through Friday, inclusive, holidays excepted.)

    1.  Sweep and damp mop floors.

    2.  Clean all mirrors, powder shelves, dispensers and receptacles, bright
work, flushometers, piping and toilet seat hinges.

    3.  Wash both sides of all toilet seats.

    4.  Wash all basins, bowls and urinals.

    5.  Dust and clean all powder room fixtures.

    6.  Empty and clean paper towel and sanitary disposal receptacles.

    7.  Remove waste paper and refuse.

    8.  Refill tissue holders, soap dispensers, towel dispensers, vending
sanitary dispensers; materials to be furnished by Landlord.

    9.  A sanitizing solution will be used in all lavatory cleaning.

    Monthly:

    1.  Machine scrub lavatory floors.

    2.  Wash all partitions and tile walls in lavatories.

C.  Main Lobby, Elevators, Building Exterior and Corridors

    Daily: (Monday through Friday, inclusive, holidays excepted.)

    1.  Sweep and wash all floors.

    2.  Wash all rubber mats.

    3.  Clean elevators, wash or vacuum floors, wipe down walls and doors.

    4.  Spot clean any metal work inside lobby.

    5.  Spot clean any metal work surrounding Building Entrance doors.

    Monthly: All resilient tile floors in public areas to be treated equivalent
to spray buffing.

D.  Window Cleaning

    Windows of exterior walls will be washed three (3) times annually.

                                      E-2
<PAGE>

E.   Common Areas

     Landlord shall keep repaired and maintain all common areas of the Property
and any sidewalks, parking areas, curbs and access ways adjoining the Property
in a clean and orderly condition. Snow and ice will be removed from exterior
sidewalks, parking areas and curbs and access ways adjoining the Property, as
necessary.

II.  HEATING, VENTILATING, AIR-CONDITIONING
     --------------------------------------

     Landlord shall furnish space heating and cooling as non-nal seasonal
changes may require to provide reasonably comfortable space temperature and
ventilation for occupants of the Premises under normal business operation,
Monday through Friday, inclusive, from 8:00 a.m. to 6:00 p.m. and Saturday from
8:00 a.m. to 1:00 p.m., holidays excepted (hereinafter referred to as "Normal
Business Hours"). As of the date of this Lease, and without any implied
limitation on Landlord's ability to change such rates at its sole discretion,
Landlord's charge for providing HVAC service to the Premises beyond Normal
Business Hours is $40.00 per hour, per floor of the Premises served.

     The HVAC system will be operated during such hours so as to maintain inside
conditions as follows:

     A.  During the summer, not more than 78 degrees Fahrenheit (plus or minus 2
degrees) and 50% relative humidity when the outside temperature does not exceed
88 degrees Fahrenheit dry bulb and 74 degrees Fahrenheit wet bulb; and

     B.  During the winter, not less than 72 degrees Fahrenheit (plus or minus 2
degrees) (no humidity control) when the outside temperature is not less than 9
degrees Fahrenheit dry bulb (no wet bulb).

     The air-conditioning system is based upon an occupancy of not more than one
person per 150 square feet of usable floor area, and upon a combined lighting
and standard electrical load not to exceed 7 watts per square foot of usable
floor area. If Tenant exceeds this condition or introduces into the Premises
equipment which overloads the system, and/or in any other way causes the system
not adequately to perform their proper functions, and the system is damaged
thereby, Landlord shall give notice thereof to Tenant and Tenant shall pay the
reasonable cost of repairing such damage (within ten (10) days of receipt of
invoice therefor), and Tenant shall immediately cease the act or omission
causing such damage; provided, however, that if Landlord agrees that the system
may be supplemented to prevent the recurrence of the problem, Landlord shall
give notice thereof to Tenant, and Tenant may elect to have such supplemental
work performed, at Tenant's sole cost and expense, by notice to Landlord within
thirty (30) days of receipt of Landlord's notice.

III. WATER
     -----

     Cold water at temperatures supplied by the City of Lowell water mains for
lavatory, toilet and other approved purposes and hot water for lavatory purposes
only from regular Building supply at prevailing temperatures; provided, however,
if Tenant requires, uses or consumes water for any purpose (~.g., kitchen
purposes, shower facilities, etc.) other than lavatory and toilet purposes,
Landlord may, at Tenant's sole cost and expense, install a meter or meters to
measure the water so supplied, in which case Tenant shall, upon Landlord's
request, reimburse Landlord for the cost of the water (including heating and
cooling thereof) consumed in such areas and the sewer use charges resulting
therefrom.

                                      E-3
<PAGE>

IV.  ELEVATORS
     ---------

     Landlord shall provide elevator service; provided, however, that Landlord
shall, from time to time, have the right to remove elevators from service as may
be required for servicing or maintaining the elevators or the Building or
removing freight.

V.   ELECTRICAL SERVICE
     ------------------

     Landlord shall furnish electric energy in accordance with base Building
electrical capacity limits and load limits of 10 watts per square foot,
exclusive of HVAC, for the operation of lighting fixtures and the 120-volt
electrical outlets initially installed in the Premises for the operation of
Tenant's normal office fixtures and equipment and for the air handlers serving
the Premises.

VI.  SECURITY
     --------

     Tenant shall have access to the Premises only through an entrance or
entrances designated by Landlord from time to time on a 24 hours per day, 7 days
per week basis. Tenant shall be solely responsible for all security within the
Premises.

                                      E-4
<PAGE>

                                   EXHIBIT F
                                   ---------

                             RULES AND REGULATIONS
                             ---------------------

     1.  Tenant shall not make any room-to-room canvas to solicit business from
other tenants in the Building and shall not exhibit, sell or offer to sell, use,
rent or exchange any item or services in -or from the Premises unless ordinarily
included within Tenant's use of the Premises as specified in the Lease.

     2.  Tenant shall not make any use of the Premises which may be dangerous to
person or property or which shall increase the cost of insurance or require
additional insurance coverage.

     3.  Tenant shall not paint, display, inscribe or affix any sign, picture,
advertisement, notice, lettering or direction or install any lights on any part
of the outside or inside of the Building, other than the Premises, and then not
on any part of the inside of the Premises which can be seen from outside the
Premises, except as approved by Landlord in writing.

     4.  Tenant shall not use the name of the Building in advertising or other
publicity, except as the address of its business, and shall not use pictures of
the Building in advertising or publicity.

     5.  Tenant shall not obstruct or place objects on or in sidewalks,
entrances, passages, courts, corridors, vestibules, halls, elevators and
stairways in and about the Building. Tenant shall not place objects against
glass partitions or doors or windows or adjacent to any open common space which
would be unsightly from the Building corridors or from the exterior of the
Building.

     6.  Bicycles shall not be permitted in the Building other than in a
location designated by Landlord.

     7.  Tenant shall not allow any animals, other than seeing eye dogs, in the
Premises or the Building.

     8.  Tenant shall not disturb other tenants or make excessive noises, cause
disturbances, create excessive vibrations, odors or noxious fumes or use or
operate any electrical or electronic devices or other devices that emit
excessive sound waves or are dangerous to other tenants of the Building or that
would interfere with the operation of any devise or equipment or radio or
television broadcasting or reception from or within the Building or elsewhere,
and shall not place or install any projections, antennae, aerials or similar
devices outside of the Building or the Premises.

     9.  Tenant shall not waste electricity or water and shall cooperate fully
with Landlord to assure the most effective operation of the Building's heating
and air conditioning systems, and shall refrain from attempting to adjust any
controls except for the thermostats within the Premises. Tenant shall keep all
doors to the Premises closed.

     10. Unless Tenant installs new doors to the Premises, Landlord shall
furnish two (2) sets of keys for all doors to the Premises at the commencement
of the Term. Tenant shall furnish Landlord with duplicate keys for any new or
additional locks on doors installed by Tenant. When the Lease is terminated,
Tenant shall deliver all keys to Landlord and will provide to Landlord the means
of opening any safes, cabinets or vaults left in the Premises.

     11. Tenant shall not install any signal, communication, alarm or other
utility or service system or equipment without the prior written consent of
Landlord.

                                      F-1
<PAGE>

     12.  Tenant shall not use any draperies or other window coverings instead
of or in addition to the Building standard window coverings designated and
approved by Landlord for exclusive use throughout the Building.

     13.  Landlord may require that all persons who enter or leave the Building
identify themselves to watchmen, by registration or otherwise. Landlord,
however, shall have no responsibility or liability for any theft, robbery or
other crime in the Building. Tenant shall assume full responsibility for
protecting the Premises, including keeping all doors to the Premises locked
after the close of business.

     14.  Tenant shall not overload floors; and Tenant shall obtain Landlord's
prior written approval as to size, maximum weight, routing and location of
business machines, safes, and heavy objects. Tenant shall not install or operate
machinery or any mechanical devices of a nature not directly related to Tenant's
ordinary use of the Premises.

     15.  In no event shall Tenant bring into the Building inflarnmables such as
gasoline, kerosene, naphtha and benzene, or explosives or firearms or any other
articles of an intrinsically dangerous nature.

     16.  Furniture, equipment and other large articles may be brought into the
Building only at the time and in the manner designated by Landlord. Tenant shall
furnish Landlord with a list of furniture, equipment and other large articles
which are to be removed from the Building, and Landlord may require permits
before allowing anything to be moved in or out of the Building. Movements of
Tenant's property into or out of the Building and within the Building are
entirely at the risk and responsibility of Tenant.

     17.  No person or contractor, unless approved in advance by Landlord, shall
be employed to do janitorial work, interior window washing, cleaning, decorating
or similar services in the Premises.

     18.  Tenant shall not use the Premises for lodging, cooking (except for
microwave reheating and coffee makers) or manufacturing or selling any alcoholic
beverages or for any illegal purposes.

     19.  Tenant shall cooperate and participate in all reasonable security
programs affecting the Building.

     20.  Tenant shall not loiter, eat, drink, sit or lie in the lobby or other
public areas in the Building. Tenant shall not go onto the roof of the Building
or any other non-public areas of the Building (except the Premises), and
Landlord reserves all rights to control the public and nonpublic areas of the
Building. In no event shall Tenant have access to any electrical, telephone,
plumbing or other mechanical closets without Landlord's prior written consent.

     21.  Tenant shall not use the freight or passenger elevators, loading docks
or receiving areas of the Building except in accordance, with regulations for
their use established by Landlord.

     22.  Tenant shall not dispose of any foreign substances in the toilets,
urinals, sinks or other washroom facilities, nor shall Tenant permit such items
to be used other than for their intended purposes; and Tenant shall be liable
for all damage as a result of a violation of this rule.

     23.  In no event shall Tenant allow its employees to use the Premises or
any portion of the public areas of the Building as smoking areas.

                                      F-2

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