Document:

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                                                                   Exhibit 10.18

                               SECURITY AGREEMENT

     This Security Agreement is made as of April 27, 2000 between Novadigm,
Inc., a Delaware corporation ("Pledgee"), and Albion Fitzgerald ("Pledgor").

                                    Recitals

     A.  The Pledgee has lent $250,000.00 to the Pledgor, such indebtedness
evidence by that certain promissory note (the "Note") attached hereto as
Exhibit A.

     B.  In consideration of the loan evidenced by the Note, the Pledgor wishes
to grant the Pledgee a security interest in certain property of the Pledgor.

     NOW, THEREFORE, it is agreed as follows:

     1.  Creation and Description of Security Interest. As security for the
Pledgor's obligations to the Pledgee, the Pledgor, pursuant to the California
Commercial Code, hereby grants to the Pledgee a security interest in 25,000
shares of Common Stock of Novadigm, Inc. (herein sometimes referred to as the
"Collateral" or as the "Shares") represented by certificate number __________,
duly endorsed in blank or with executed stock powers, and herewith delivers
said certificate to the Secretary of Pledgee ("Pledgeholder"), who shall hold
said certificate subject to the terms and conditions of this Security Agreement.

     The pledged stock (together with an executed blank stock assignment,
attached hereto as Exhibit B, for use in transferring all or a portion of the
Shares to Pledgee if, as and when required pursuant to this Security Agreement)
shall be held by the Pledgeholder as security for the repayment of the Note,
and any extensions or renewals thereof, to be executed by Pledgor pursuant to
the terms of the Agreement, and the Pledgeholder shall not encumber or dispose
of such Shares except in accordance with the provisions of this Security
Agreement.

     2.  Pledgor's Representations and Covenants. To induce Pledgee to enter
into this Security Agreement, Pledgor represents and covenants to Pledgee, its
successors and assigns, as follows:

          (a) Payment of Indebtedness. Pledgor will pay the principal sum of
the Note secured hereby, together with interest thereon, at the time and in the
manner provided in the Note.

          (b) Encumbrances. The Shares are free of all other encumbrances,
defenses and liens (other than restrictions on transfer imposed by applicable
securities laws), and Pledgor will not further encumber the Shares without the
prior written consent of Pledgee.

          (c) Margin Regulations. In the event that Pledgee's Common Stock is
now or later becomes margin-listed by the Federal Reserve Board and Pledgee is
classified as a "lender" within the meaning of the regulations under Part 207
of Title 12 of the Code of Federal Regulations ("Regulation G"), Pledgor agrees
to cooperate with Pledgee in making any amendments to the Note or providing any
additional collateral as may be necessary to comply with such regulations.

<PAGE>   2
     3.   Voting Rights. During the term of this pledge and so long as all
payments of principal and interest are made as they become due under the terms
of the Note, Pledgor shall have the right to vote all of the Shares pledged
hereunder.

     4.   Stock Adjustments. In the event that during the term of the pledge
any stock dividend, reclassification, readjustment or other changes are
declared or made in the capital structure of Pledgee, all new, substituted and
additional shares or other securities issued by reason of any such change shall
be delivered to and held by the Pledgee under the terms of this Security
Agreement in the same manner as the Shares originally pledged hereunder. In the
event of substitution of such securities, Pledgor, Pledgee and Pledgeholder
shall cooperate and execute such documents as are reasonable so as to provide
for the substitution of such Collateral and, upon such substitution, references
to "Shares" in this Security Agreement shall include the substituted shares of
capital stock of Pledgor as a result thereof.

     5.   Options and Rights. In the event that, during the term of this
pledge, subscription Options or other rights or options shall be issued in
connection with the pledged Shares, such rights, Options and options shall be
the property of Pledgor and, if exercised by Pledgor, all new stock or other
securities so acquired by Pledgor as it relates to the pledged Shares then held
by Pledgeholder shall be immediately delivered to Pledgeholder, to be held
under the terms of this Security Agreement in the same manner as the Shares
pledged.

     6.   Default. Pledgor shall be deemed to be in default of the Note and of
this Security Agreement in the event:

          (a)  Payment of principal or interest on the Note shall be delinquent
for a period of 45 days or more; or

          (b)  Pledgor fails to perform any of the covenants set forth in the
Agreement or contained in this Security Agreement for a period of 10 days after
written notice thereof from Pledgee.

     In the case of an event of Default, as set forth above, Pledgee shall have
the right to accelerate payment of the Note upon notice to Pledgor, and Pledgee
shall thereafter be entitled to pursue its remedies under the California
Commercial Code.

     7.   Release of Collateral. Subject to any applicable contrary rules under
Regulation G, there shall be released from this pledge a portion of the pledged
Shares held by Pledgeholder hereunder upon payments of the principal of the
Note. The number of the pledged Shares which shall be released shall be that
number of full Shares which bears the same proportion to the initial number of
Shares pledged hereunder as the payment of principal bears to the initial full
principal amount of the Note.

     8.   Withdraw or Substitution of Collateral. Pledgor shall not sell,
withdraw, pledge, substitute or otherwise dispose of all or any part of the
Collateral without the prior written consent of Pledgee.

                                      -2-
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     9. Term. The within pledge of Shares shall continue until the payment of
all indebtedness secured hereby, at which time the remaining pledged stock
shall be promptly delivered to Pledgor, subject to the provisions for prior
release of a portion of the Collateral as provided in paragraph 7 above.

     10. Insolvency. Pledgor agrees that if a bankruptcy or insolvency
proceeding is instituted by or against it, or if a receiver is approved for the
property of Pledgor, or if Pledgor makes an assignment for the benefit of
creditors, the entire amount unpaid on the Note shall become immediately due
and payable, and Pledgee may proceed as provided in the case of default.

     11. Pledgeholder Liability. In the absence of willful or gross negligence,
Pledgeholder shall not be liable to any party for any of his acts, or omissions
to act, as Pledgeholder.

     12. Invalidity of Particular Provisions. Pledgor and Pledgee agree that the
enforceability or invalidity of any provision or provisions of this Security
Agreement shall not render any other provision or provisions herein contained
unenforceable or invalid.

     13. Successors or Assigns. Pledgor and Pledgee agree that all of the terms
of this Security Agreement shall be binding on their respective successors and
assigns, and that the term "Pledgor" and the term "Pledgee" as used herein
shall be deemed to include, for all purposes, the respective designees,
successors, assigns, heirs, executors and administrators.

     14. Governing Law. This Security Agreement shall be interpreted and
governed under the laws of the State of California.

                                      -3-
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     IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of
the day and year first above written.

     "PLEDGOR"

     By: /s/  ALBION FITZGERALD
     --------------------------------------
     Albion Fitzgerald

     Address:
             ------------------------------

             ------------------------------

     "PLEDGEE"

     NOVADIGM, INC., a Delaware corporation

     By: /s/ WALLACE D. RUIZ
     --------------------------------------

     Print Name: Wallace D. Ruiz
                ---------------------------

     Title:  VP & CFO
           --------------------------------

     "PLEDGEHOLDER"

     By: /s/ ROBERT ANDERSON
     --------------------------------------
     Secretary of Novadigm, Inc.

                                      -4-<PAGE>   1
                                                                   EXHIBIT 10.19

                               SECURITY AGREEMENT

     This Security Agreement is made as of April 17, 2000 between Novadigm,
Inc., a Delaware corporation ("Pledgee"), and Wallace Ruiz ("Pledgor").

                                    Recitals

     Pursuant to Pledgor's purchase of Shares under a Stock Option Agreement
(the "Agreement"), between Pledgor and Pledgee and Pledgor's election to pay
for such shares with funds from Pledgor's promissory note (the "Note"), Pledgor
has purchased 130,000 shares of Pledgee's Common Stock (the "Shares") at a
price of $5.25 per share, for a total purchase price of $682,500.00 and the
advance of $147,568.00 by Pledgee for payment of related income taxes of
Pledgor. The Note and the obligations thereunder are as set forth in Exhibit A
attached hereto.

     NOW, THEREFORE, it is agreed as follows:

     1. Creation and Description of Security Interest. In consideration of the
transfer of the Shares to Pledgor under the Agreement, Pledgor, pursuant to the
California Commercial Code, hereby pledges all of such Shares (herein sometimes
referred to as the "Collateral") represented by certificate number ____, duly
endorsed in blank or with executed stock powers, and herewith delivers said
certificate to the Secretary of Pledgee ("Pledgeholder"), who shall hold said
certificate subject to the terms and conditions of this Security Agreement.

     The pledged stock (together with an executed blank stock assignment,
attached hereto as Exhibit B, for use in transferring all or a portion of the
Shares to Pledgee if, as and when required pursuant to this Security Agreement)
shall be held by the Pledgeholder as security for the repayment of the Note,
and any extensions or renewals thereof, to be executed by Pledgor pursuant to
the terms of the Agreement, and the Pledgeholder shall not encumber or dispose
of such Shares except in accordance with the provisions of this Security
Agreement.

     2. Pledgor's Representations and Covenants. To induce Pledgee to enter
into this Security Agreement, Pledgor represents and covenants to Pledgee, its
successors and assigns, as follows:

          (a) Payment of Indebtedness. Pledgor will pay the principal sum of
the Note secured hereby, together with interest thereon, at the time and in the
manner provided in the Note.

          (b) Encumbrances. The Shares are free of all other encumbrances,
defenses and liens (other than restrictions on transfer imposed by applicable
securities laws), and Pledgor will not further encumber the Shares without the
prior written consent of Pledgee.

          (c) Margin Regulations. In the event that Pledgee's Common Stock is
now or later becomes margin-listed by the Federal Reserve Board and Pledgee is
classified as a "lender" within the meaning of the regulations under Part 207
of Title 12 of the Code of Federal Regulations ("Regulation G"), Pledgor agrees
to cooperate with Pledgee in making any amendments to the Note or providing any
additional collateral as may be necessary to comply with such regulations.
<PAGE>   2
     3.   Voting Rights. During the term of this pledge and so long as all
payments of principal and interest are made as they become due under the terms
of the Note, Pledgor shall have the right to vote all of the Shares pledged
hereunder.

     4.   Stock Adjustments. In the event that during the term of the pledge
any stock dividend, reclassification, readjustment or other changes are
declared or made in the capital structure of Pledgee, all new, substituted and
additional shares or other securities issued by reason of any such change shall
be delivered to and held by the Pledgee under the terms of this Security
Agreement in the same manner as the Shares originally pledged hereunder. In the
event of substitution of such securities, Pledgor, Pledgee and Pledgeholder
shall cooperate and execute such documents as are reasonable so as to provide
for the substitution of such Collateral and, upon such substitution, references
to "Shares" in this Security Agreement shall include the substituted shares of
capital stock of Pledgor as a result thereof.

     5.   Options and Rights. In the event that, during the term of this
Pledge, subscription Options or other rights or options shall be issued in
connection with the pledged Shares, such rights, Options and options shall be
the property of Pledgor and, if exercised by Pledgor, all new stock or other
securities so acquired by Pledgor as it relates to the pledged Shares then held
by Pledgeholder shall be immediately delivered to Pledgeholder, to be held under
the terms of this Security Agreement in the same manner as the Shares pledged.

     6.   Default. Pledgor shall be deemed to be in default of the Note and of
this Security Agreement in the event:

          (a)  Payment of principal or interest on the Note shall be delinquent
for a period of 45 days or more; or

          (b)  Pledgor fails to perform any of the covenants set forth in the
Agreement or contained in this Security Agreement for a period of 10 days after
written notice thereof from Pledgee.

     In the case of an event of Default, as set forth above, Pledgee shall have
the right to accelerate payment of the Note upon notice to Pledgor, and Pledgee
shall thereafter be entitled to pursue its remedies under the California
Commercial Code.

     7.   Release of Collateral. Subject to any applicable contrary rules under
Regulation G, there shall be released from this Pledge a portion of the pledged
Shares held by Pledgeholder hereunder upon payments of the principal of the
Note. The number of the pledged Shares which shall be released shall be that
number of full Shares which bears the same proportion to the initial number of
Shares pledged hereunder as the payment of principal bears to the initial full
principal amount of the Note.

     8.   Withdrawal or Substitution of Collateral. Pledgor shall not sell,
withdraw, pledge, substitute or otherwise dispose of all or any part of the
Collateral without the prior written consent of Pledgee.

                                      -2-

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     9.   Term. The within pledge of Shares shall continue until the payment of
all indebtedness secured hereby, at which time the remaining pledged stock
shall be promptly delivered to Pledgor, subject to the provisions for prior
release of a portion of the Collateral as provided in paragraph 7 above.

     10.  Insolvency. Pledgor agrees that if a bankruptcy or insolvency
proceeding is instituted by or against it, or if a receiver is appointed for
the property of Pledgor, or if Pledgor makes an assignment for the benefit of
creditors, the entire amount unpaid on the Note shall become immediately due
and payable, and Pledgee may proceed as provided in the case of default.

     11.  Pledgeholder Liability. In the absence of willful or gross
negligence, Pledgeholder shall not be liable to any party for any of his acts,
or omissions to act, as Pledgeholder.

     12.  Invalidity of Particular Provisions. Pledgor and Pledgee agree that
the enforceability or invalidity of any provision or provisions of this
Security Agreement shall not render any other provision or provisions herein
contained unenforceable or invalid.

     13.  Successors or Assigns. Pledgor and Pledgee agree that all of the
terms of this Security Agreement shall be binding on their respective
successors and assigns, and that the term "Pledgor" and the term "Pledgee" as
used herein shall be deemed to include, for all purposes, the respective
designee, successors, assigns, heirs, executors and administrators.

     14.  Governing Law. This Security Agreement shall be interpreted and
governed under the laws of the State of California.

                                      -3-

<PAGE>   4
      IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of
the day and year first above written.

      "PLEDGOR"

      /s/ WALLACE RUIZ
      -------------------------------------
      Wallace Ruiz

      Address:  9828 SW 108 Terrace
              -----------------------------
                Miami, FL 33176

      "PLEDGEE"

      NOVADIGM, INC., a Delaware corporation

      By:  /s/ ALBION J. FITZGERALD
         ----------------------------------

      Print Name:  Albion J. Fitzgerald
                 --------------------------

      Title:  Chairman
            -------------------------------

      "PLEDGEHOLDER"

      /s/  ROBERT ANDERSON
      -------------------------------------
      Secretary of Novadigm, Inc.

                                      -4-

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