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                                                                  EXHIBIT 10.12


                      LANDA MANAGEMENT SYSTEMS CORPORATION

                                VOTING AGREEMENT

     THIS VOTING AGREEMENT (the "Agreement") is made and entered into this 27th
day of February, 1998, by and among LANDA MANAGEMENT SYSTEMS CORPORATION, a
California corporation (the "Company"), those certain holders of the Company's
Common Stock and options to purchase Common Stock listed on Exhibit A hereto
(the "Key Shareholders") and the persons and entries listed on Exhibit B hereto
(the "Investors").

                                  WITNESSETH:

     WHEREAS, the Key Shareholders are the beneficial owners of an aggregate
of seven hundred fifty-eight thousand four hundred seventy-seven and
eighty-three one hundredths (758,477.83) shares of Common Stock and/or options
to purchase three hundred sixty-eight thousand eight hundred forty-eight
(368,848) shares of Common Stock and/or warrants to purchase three hundred fifty
thousand (350,000) shares of Common Stock of the Company; and

     WHEREAS, the Company proposes to sell shares of its Series D Preferred
Stock, (the "Series D Preferred Stock"), to the Investors pursuant to the
Series D Preferred Stock Purchase Agreement (the "Purchase Agreement") of even
date herewith (the "Financing");

     WHEREAS, in connection with the consummation of the Financing, the
Company, the Key Shareholders and the Investors have agreed to provide for the
future voting of their shares of the Company's capital stock as set forth below;

     NOW, THEREFORE, in consideration of the premises and for other good and
valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, the parties hereto agree as follows:


                                   ARTICLE 1

                                     VOTING

     1.1 COMMON SHARES; INVESTOR SHARES.

          1.1.1 The Key Shareholders each agree to hold all shares of voting
capital stock of the Company registered in their respective names or
beneficially owned by them as of the date hereof, and any and all other
securities of the Company legally or beneficially acquired by each of the Key
Shareholders after the date hereof (including but not limited to all shares of
Common Stock issued upon exercise of options and/or warrants to purchase Common
Stock; hereinafter collectively referred to as the "Common Shares"), subject to,
and to vote the Common Shares in accordance with, the provisions of this
Agreement.

          1.1.2 The Investors each agree to hold all shares of voting capital
stock of the Company now owned or hereinafter acquired by them (including but
not limited to all shares of Common Stock issued upon conversion of the
Company's Series D Preferred Stock) registered in their respective


                                       1.
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names or beneficially owned by them as of the date hereof and any and all other
securities of the Company legally or beneficially acquired by each of the
Investors after the date hereof) (hereinafter collectively referred to as the
"Investor Shares") subject to, and to vote the Investor Shares in accordance
with, the provisions of this Agreement.

     1.2  VOTING.

          (a)  At each election of directors in which the holders of Common
Stock and holders of Preferred Stock, voting together as a single class, are
entitled to elect directors of the Company, the Key Shareholders and Investors
shall consult each other and shall vote their respective shares of the Company's
voting stock so that at least such directors will be nominees that are mutually
acceptable to a majority in interest of the holders of Series D Preferred Stock.
It is anticipated that one of the directors to be elected pursuant to this
section will be Bryan Lang for so long as he remains an employee of the Company.

          (b)  Each Key Shareholder and each Investor agrees to vote its voting
stock in accordance with the voting of holders of a majority in interest of the
Series D Preferred Stock with respect to (i) the approval of any proposed
amendment to the Amended and Restated Articles of Incorporation of the Company
(the "Restated Articles"), (ii) the approval of any proposed amendment to the
Amended and Restated Bylaws of the Company, and (iii) any proposed Acquisition
or Asset Transfer (as each such term is defined in the Restated Articles).

     1.3  LEGEND.

          1.3.1     Concurrently with the execution of this Agreement, there
shall be imprinted or otherwise placed, on certificates representing the Common
Shares and the Investor Shares, and such legend shall be imprinted on each
Common Share issued upon exercise by a Key Shareholder of an option to purchase
Common Stock, the following restrictive legend (the "Legend"):

          "THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT
          TO THE TERMS AND CONDITIONS OF A VOTING AGREEMENT WHICH
          PLACES CERTAIN RESTRICTIONS ON THE VOTING OF THE SHARES
          REPRESENTED HEREBY. ANY PERSON ACCEPTING ANY INTEREST IN
          SUCH SHARES SHALL BE DEEMED TO AGREE TO AND SHALL BECOME
          BOUND BY ALL THE PROVISIONS OF SUCH AGREEMENT. A COPY OF
          SUCH VOTING AGREEMENT WILL BE FURNISHED TO THE RECORD HOLDER
          OF THIS CERTIFICATE WITHOUT CHARGE UPON WRITTEN REQUEST
          TO THE COMPANY AT ITS PRINCIPAL PLACE OF BUSINESS."

          1.3.2     The Company agrees that, during the term of this Agreement,
it will not remove, and will not permit to be removed (upon registration of
transfer, reissuance of otherwise), the Legend from any such certificate and
will place or cause to be placed the Legend on any new certificate issued to
represent Common Shares or Investor Shares theretofore represented by a
certificate carrying the Legend.

     1.4  SUCCESSORS. The provisions of this Agreement shall be binding upon
the successors in interest to any of the Common Shares or Investor Shares. The
Company shall not permit the transfer of


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any of the Common Shares or Investor Shares on its books or issue a new
certificate representing any of the Common Shares or Investor Shares unless and
until the person to whom such security is to be transferred shall have executed
a written Agreement, substantially in the form of this Agreement, pursuant to
which such person becomes a party to this Agreement and agrees to be bound by
all the provisions hereof as if such person were a Key Shareholder or Investor,
as applicable. Notwithstanding the foregoing, upon any transfer effected
pursuant to Section 2.3 of the Purchase Agreement, such transferee shall be
deemed to be an Investor hereunder and the shares of voting capital stock of the
Company then transferred to it and/or thereafter acquired by it shall be deemed
"Investor Shares."

     1.5  OTHER RIGHTS. Except as provided by this Agreement, each key
Shareholder and Investor shall exercise the full rights of a shareholder with
respect to the Common Shares and the Investor Shares, respectively.


                                   ARTICLE 2

                                  TERMINATION

     2.1  This Agreement shall continue in full force and effect from the date
hereof through the earliest of the following dates, on which it shall terminate
in its entirety:

          2.1.1 the date of the closing of a firmly underwritten public offering
of the Company's Common Stock pursuant to a registration statement filed with,
and declared effective under the Securities Act of 1933, as amended; or

          2.1.2 at such time as the Investors hold less than One Million
(1,000,000) shares of Series D Preferred Stock (as adjusted for stock splits
and the like); or

          2.1.3 ten (10) years from the date of this Agreement; or

          2.1.4 the date as of which the parties hereto terminate this
Agreement by written consent of a majority in interest of the Investors and a
majority in interest of the Key Shareholders.


                                   ARTICLE 3

                                 MISCELLANEOUS

     3.1  OWNERSHIP. Each Key Shareholder represents and warrants to the
Investors that (a) he now owns the Common Shares and/or Options and/or Warrants
to purchase Common Stock of the Company set forth opposite such person's name on
Exhibit A hereto, free and clear of liens or encumbrances, and has not, prior to
or on the date of this Agreement, executed or delivered any proxy or entered
into any other voting agreement or similar arrangement other than on which has
expired or terminated prior to the date hereof, and (b) such Key Shareholder has
full power and capacity to execute, deliver and perform this Agreement, which
has been duly executed and delivered by, and evidences the valid and binding
obligation of, such Key Shareholder enforceable in accordance with its terms.

     3.2  FURTHER ACTION. If and when the Common Shares are sold, each Key
Shareholder (or the personal representative of any Key Shareholder) shall do all
things and execute and deliver all documents and make all transfers, and cause
any transferee of the Common Shares to do all things and


                                       3.
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execute and deliver all documents, as may be necessary to consummate such sale
consistent with this Agreement.

     3.3  SPECIFIC PERFORMANCE. The parties hereto hereby declare that it is
impossible to measure in money the damages which will accrue to a party hereto
or to their heirs, personal representatives, or assigns by reason of a failure
to perform any of the obligations under this Agreement and agree that the terms
of this Agreement shall be specifically enforceable. If any party hereto or his
heirs, personal representatives, or assigns institutes any action of proceeding
to specifically enforce the provisions hereof, any person against whom such
action or proceeding is brought hereby waives the claim or defense therein that
such party or such personal representative has an adequate remedy at law, and
such person shall not offer in any such action or proceeding the claim or
defense that such remedy at law exists.

     3.4  GOVERNING LAW. This Agreement, and the rights of the parties hereto,
shall be governed by and construed in accordance with the laws of the State of
California as such laws apply to agreements among California residents made and
to be performed entirely within the State of California.

     3.5  AMENDMENT. This Agreement may be amended only by an instrument in
writing signed by the Company, a majority in interest of the Investors and a
majority in interest of the Key Shareholders.

     3.6  SEVERABILITY. If any provision of this Agreement is held to be invalid
or unenforceable, the validity and enforceability of the remaining provisions of
this Agreement shall not be affected thereby.

     3.7  SUCCESSORS. This Agreement shall inure to the benefit of and be
binding upon the parties hereto and their respective heirs, successors, assigns,
administrators, executors and other legal representatives.

     3.8  ADDITIONAL SHARES. In the event that subsequent to the date of this
Agreement any shares or other securities (other than any shares or securities of
another corporation issued to the Company's shareholders pursuant to a plan of
merger) are issued on, or in exchange for, any of the Common Shares or Investor
Shares by reason of any stock dividend, stock split, consolidation of shares,
reclassification or consolidation involving the Company, such shares or
securities shall be deemed to be Common Shares or Investor Shares, as the case
may be, for purposes of this Agreement.

     3.9  COUNTERPARTS. This Agreement may be executed in one or more
counterparts, each of which will be deemed an original but all of which together
shall constitute one and the same agreement.

     3.10 WAIVER. No waivers of any breach of this Agreement extended by any
party hereto to any other party shall be construed as a waiver of any rights or
remedies of any other party hereto or with respect to any subsequent breach.

     3.11 ATTORNEY'S FEES. In the event that any suit or action is instituted to
enforce any provision in this Agreement, the prevailing party shall be entitled
to all costs and expenses of maintaining such suit or action, including
reasonable attorneys' fees.



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     3.12 ENTIRE AGREEMENT. This Agreement and the Exhibits hereto, along with
the Purchase Agreement and each of the Exhibits thereto, constitute the full and
entire understanding and agreement between the parties with regard to the
subjects hereof and thereof and no party shall be liable or bound to any other
in any manner by any representations, warranties, covenants and agreements
except as specifically set forth herein and therein.


                     [THIS SPACE INTENTIONALLY LEFT BLANK]

















                                       5.
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     IN WITNESS WHEREOF, the parties hereto have executed this VOTING AGREEMENT
as of the date first above written.


COMPANY:                                INVESTORS:

LANDA MANAGEMENT SYSTEMS CORPORATION    BEDROCK CAPITAL PARTNERS, L.L.P.


By:                                     By:
   ---------------------------------       ------------------------------------
     President                               General Partner


KEY SHAREHOLDERS:                       BEDROCK CAPITAL SIDE-BY-SIDE, L.P.


                                        By:
------------------------------------       ------------------------------------
BRYAN LANG                                   General Partner


------------------------------------    GREYLOCK IX LIMITED PARTNERSHIP
STEPHEN KAY                             By: Greylock IX GP Limited Partnership
                                        Its General Partner


                                        By:
------------------------------------       ------------------------------------
SHAREHOLDER                                  General Partner


                                        SEQUOIA CAPITAL VII,
                                        A CALIFORNIA LIMITED PARTNERSHIP
                                        By:  SC  VII-A  Management, LLC A
California
                                        Limited Liability Company,
                                        Its General Partner


                                        By:
                                           ------------------------------------
                                             Managing Member


                                        SEQUOIA TECHNOLOGY PARTNERS VII
                                        A CALIFORNIA LIMITED PARTNERSHIP
                                        By:  SC  VII-A  Management, LLC A
California
                                        Limited Liability Company,
                                        Its General Partner


                                        By:
                                           ------------------------------------
                                             Managing Member






                       SIGNATURE PAGE TO VOTING AGREEMENT
<PAGE>   7
                                        SQP 1997

                                        BY: SC VII-A MANAGEMENT, LLC A
                                        CALIFORNIA LIMITED LIABILITY COMPANY,
                                        ITS GENERAL PARTNER

                                        By:
                                           ---------------------------
                                             Managing Member

                                        SEQUOIA 1997 LLC

                                        BY: SC VII-A MANAGEMENT, LLC A
                                        CALIFORNIA LIMITED LIABILITY COMPANY,
                                        IT'S GENERAL PARTNER

                                        By:
                                           ---------------------------
                                             Managing Member

                                        SEQUOIA INTERNATIONAL PARTNERS

                                        BY: SC VII-A MANAGEMENT, LLC A
                                        CALIFORNIA LIMITED LIABILITY COMPANY,
                                        IT'S GENERAL PARTNER

                                        By:
                                           ---------------------------
                                             Managing Member

                                        ------------------------------
                                        GENE CATTARINA




                                        ------------------------------
                                        JOHN KARLEN




                       SIGNATURE PAGE TO VOTING AGREEMENT