Document:

EXHIBIT 10.25.1.

                                 PROMISSORY NOTE
                                 ---------------

$3,375,000                                                          July 1, 2001

         For value received, the undersigned,  GREENBRIAR CORPORATION, having an
address at Centura Tower I, Suite 650, 14185 Dallas Parkway, Dallas, Texas 75240
(hereinafter referred to as "MAKER"),  promises to pay to the order of SYLVIA M.
GILLEY, at 6211 Georgian Court,  Dallas,  Texas 75240 (hereinafter  collectively
referred to as "HOLDER"),  the  principal  amount of THREE MILLION THREE HUNDRED
SEVENTY FIVE THOUSAND ($3,375,000) DOLLARS, together with interest on the unpaid
principal  balance  thereof  at the rate of TEN (10%)  percent  per  annum.  All
accrued and unpaid  interest on this Note shall be due and payable,  and must be
received  by  Holder,  on  October  1, 2001 and on the first day of every  three
months thereafter.  Notwithstanding  any provision to the contrary in this Note,
payment of principal  and interest of this Note is to be made only if and to the
extent that payment of a distribution to stockholders of Greenbriar  Corporation
could then be made pursuant to NRS 78.288. Maker may prepay this Note in full or
in part at any time, without premium or penalty.  The entire outstanding balance
evidenced by this Note, including,  without limitation,  all unpaid interest and
any other amounts that may be due hereunder, shall be due and payable in full on
the date which is TWO (2) YEARS from the date  hereof.  All  payments  hereunder
shall be applied first to: (i) any amounts due hereunder other than for interest
or  principal,  then (ii) to  accrued  and  unpaid  interest  and then  (iii) to
principal.

         Notwithstanding  any provision to the contrary in this Note,  the total
obligation for payments which are legally  regarded as interest shall not exceed
the maximum limits imposed by applicable state and federal laws in effect on the
date  hereof,  and no payment  shall be made  hereunder  if such  payment  would
otherwise violate any other provision of any applicable State or Federal law. If
any payment in excess of said limits is provided for, or shall be adjudicated to
be provided  for, in this Note then,  in any such event:  (i) the  provisions of
this paragraph  shall govern and control and supersede  every other provision of
this Note,  (ii) neither  Maker nor its  successors,  legal  representatives  or
assigns,  nor any other party  liable for the payment of any sum due pursuant to
this Note shall be  obligated  to pay such  amount to the  extent  that it is in
excess of the maximum  amount or otherwise not permitted by law,  (iii) any such
excess  interest or other payment which may have been  collected  shall,  at the
option of the Holder (unless otherwise  required by law), either be applied as a
credit  against  the then  unpaid  principal  amount of this Note or refunded to
Maker, and (iv) the effective rate of interest shall be automatically subject to
reduction to the maximum lawful contract rate allowed under any applicable State
or Federal laws in effect on the date hereof.

         If Maker fails to promptly  pay any amount  required to be paid by this
Note when  DEMANDED,  and the same is placed  in the  hands of an  attorney  for
collection,  or suit is brought on the same,  or the same is  collected  through
probate,  bankruptcy  or other  judicial  proceedings,  or any  other  costs are
incurred by Holder in connection  with the  collection  of the same,  then Maker
agrees and promises to pay all such costs of  collection,  including  reasonable
attorney's fees and court costs, whether or not a lawsuit is brought.

                                Page 199 of 200
<PAGE>

         Maker waives all notices, demands for payment, presentment for payment,
notice of dishonor,  notice of protest,  protest,  and diligence in  collection.
Maker shall pay Holder all sums which are payable  pursuant to the terms of this
Note without  setoff,  recoupment or deduction of any kind. No provision of this
Note may be  waived,  changed,  modified,  amended  or  discharged,  except by a
written  agreement  which is signed by the party  against  whom  enforcement  is
sought.  Maker hereby irrevocably  waives its right to a Jury Trial,  submits to
the law and  jurisdiction  of the Courts of the State where this Note is payable
and agrees that venue shall lie in the County where this Note is payable.

         IN WITNESS  WHEREOF,  the Maker has  executed  this  Note,  by its duly
authorized representative, as of the day and year first above written.

                                          MAKER:
                                                 GREENBRIAR CORPORATION

                                                 By:____________________________
                                                        Gene S. Bertcher,
                                                        Executive Vice President

STATE OF TEXAS    )
                  ) s.s.:
COUNTY OF DALLAS  )

         On the ____ day of June, in the year 2001,  before me, the undersigned,
a Notary Public in and for said state,  personally  appeared  GENE S.  BERTCHER,
personally know to me or proved to me on the basis of  satisfactory  evidence to
be the person(s) whose name(s) is (are) subscribed to the within  instrument and
acknowledged  to  me  that  he/she/they   executed  the  same  in  his/her/their
capacity(ies),  and that by  his/her/their  signature(s) on the instrument,  the
person(s),  or the entity upon behalf of which the person(s) acted, executed the
instrument.

                                                      __________________________
                                                             Notary Public

                                Page 200 of 200<PAGE>

                                                                     EXHIBIT 4.3

                          REGISTRATION RIGHTS AGREEMENT

        THIS REGISTRATION RIGHTS AGREEMENT (this "Agreement") is made as of the
30th day of May, 2001 (the "Closing Date") by and between Actuate Corporation, a
Delaware corporation (the "Company"), and Michael J. Gassman (the "Stockholders'
Representative") as the duly appointed representative of the stockholders of
Tidestone Technologies, Inc. listed on Schedule A hereto (the "Stockholders").

                              W I T N E S S E T H:

        WHEREAS, the Company, TT Acquisition Corp., a Delaware corporation and a
wholly owned subsidiary of the Company, Tidestone Technologies, Inc., a Kansas
corporation ("Tidestone"), and the Stockholders' Representative are parties to
the Agreement and Plan of Merger and Reorganization, dated as of the Closing
Date (together with all exhibits, schedules, supplements and any amendments
thereto, the "Merger Agreement"), pursuant to which the Company shall acquire
Tidestone in the manner set forth therein (the "Merger");

        WHEREAS, pursuant to the Merger Agreement, the Stockholders shall
exchange the shares of capital stock of Tidestone held by such Stockholders for
shares of common stock of the Company, par value $0.001 per share (the "Common
Stock");

        WHEREAS, the execution and delivery of this Agreement is a condition to
the Closing of the Merger; and

        WHEREAS, all terms not otherwise defined herein shall have the same
meanings ascribed to them in the Merger Agreement.

        NOW, THEREFORE, the parties hereby agree as follows:

        1. Registration Rights. The Company covenants and agrees as follows:
           -------------------

           1.1   Definitions.  For purposes of this Section 1:
                 -----------

                 (a) The term "Act" means the Securities Act of 1933, as
amended.

                 (b) The term "1934 Act" shall mean the Securities Exchange Act
of 1934, as amended.

                 (c) The term "Holder" means a Stockholder issued Common Stock
in the Merger.

                 (d) The term "Permitted Transferee" means:

                     (i)    a Stockholder's immediate family member or a trust
established for the benefit of a Stockholder's immediate family member or a
charitable organization (as defined in Rule 501(c)(3) of the Internal Revenue
Code of 1986, as amended) in

<PAGE>

each case that receives Registrable Securities by means of a bona fide gift;
provided that (A) such transfer of the underlying Registrable Securities is
--------
effected prior to July 15, 2001, (B) such transferee agrees in writing to be
bound by and subject to the terms and conditions of this Agreement and (C) such
transferee promptly furnishes the information requested on Appendix 1.4 hereto
                                                           ------------
to the Company; or

                     (ii)   a Stockholder listed on Schedule A hereto; provided
                                                    ----------         --------
that such transfer of the underlying Registrable Securities is effected prior to
the effective date of the registration statement filed pursuant to this
Agreement and such transferee promptly notifies the Company in writing of the
number of Registrable Securities then held by him, her or it after the transfer.

                 (e) The terms "register," "registered," and "registration"
refer to a registration effected by preparing and filing a registration
statement or similar document in compliance with the Act, and the declaration or
ordering of effectiveness of such registration statement or document.

                 (f) The term "Registrable Securities" means the Common Stock of
the Company issued to the Stockholders in the Merger, and any Common Stock of
the Company issued as a dividend or other distribution with respect to such
Common Stock.

                 (g) The term "Rule 144" shall mean Rule 144 promulgated under
the Act, as amended, or any similar successor rule thereto that may be
promulgated by the SEC.

                 (h) The term "SEC" shall mean the Securities and Exchange
Commission.

           1.2   Registration.  (a) The Company shall prepare and, on or before
                 ------------
July 31, 2001, file with the SEC a registration statement for an offering to be
made on a continuous basis pursuant to SEC Rule 145 under the Act to register
for resale all of the Registrable Securities. The Registration Statement shall
be on Form S-3. The Company shall use its commercially reasonable efforts to
cause the registration statement to be declared effective under the Act as
promptly as possible after the filing thereof. The Company agrees to request the
immediate acceleration of the effectiveness of the registration statement as
soon as practicable but no less than within three (3) business days of any
notification by the SEC of its decision not to review the registration statement
or its determination that it has completed its review of the registration
statement and has no further comments for the Company.

                 (b) In the event that Form S-3 is not available at the time it
is required to be filed, the registration statement shall be filed on a
successor to Form S-3 or if there is no clear successor form, or if the Company
is not eligible to use Form S-3 or a successor form, then the registration shall
be filed using such form as may be available that is least burdensome for the
Company.

                                       2

<PAGE>

           1.3   Obligations of the Company.  In connection with the Company's
                 --------------------------
obligation under this Section 1 to effect the registration of any Registrable
Securities, the Company shall:

                 (a) Prepare and file with the SEC a registration statement with
respect to such Registrable Securities and thereafter use its commercially
reasonable efforts to cause such registration statement to become effective as
soon as practicable after July 31, 2001, and, subject to the provisions below,
use its commercially reasonable efforts to keep such registration statement
effective until the earlier of (i) August 31, 2003 or (ii) such earlier date at
which all Registrable Securities covered by such registration statement have
been sold or may be sold in a single three (3) month period pursuant to Rule 144
(the "Effective Period").

                 (b) Subject to subsection 1.3(a), prepare and file with the SEC
such amendments and supplements to such registration statement and the
prospectus used in connection with such registration statement as may be
necessary to comply with the provisions of the Act with respect to the
disposition of all securities covered by such registration statement and subject
to any limitations as set forth in this Agreement, as may be reasonably
necessary to keep the registration statement continuously effective as to the
Registrable Securities for the Effective Period.

                 (c) Furnish to the Stockholders without charge such number of
copies of such registration statement and prospectus, including a preliminary
prospectus and any amendments or supplements thereto, in conformity with the
requirements of the Act, and such other documents as they may reasonably request
in order to facilitate the disposition of Registrable Securities owned by them.

                 (d) Use its commercially reasonable efforts to register and
qualify the securities covered by such registration statement under such other
state securities or Blue Sky laws of such jurisdictions as shall be reasonably
requested by the Stockholders; provided that the Company shall not be required
in connection therewith or as a condition thereto to qualify to do business or
to file a general consent to service of process in any such states or
jurisdictions unless the Company is already qualified to do business or is
subject to service in such jurisdiction and except as may be required by the
Act.

                 (e) If necessary, amend its listing application with The Nasdaq
Stock Market to include the Registrable Securities as soon as practicable after
the Closing Date.

                 (f) Notify each Stockholder who holds Registrable Securities,
promptly after the Company has received notice thereof, (i) of the date and time
the registration statement and each post-effective amendment thereto has become
effective or a supplement to any prospectus forming a part of such registration
statement has been filed; (ii) of the receipt by the Company of any notification
with respect to the suspension of qualification or exemption from qualification
of any Registrable Securities for sale in any jurisdiction; or (iii) of the
issuance of any stop order by the SEC suspending the effectiveness of the
registration statement covering the Registrable Securities.

                                       3

<PAGE>

        Notwithstanding the provisions of this Section 1.3, the Company shall
be entitled to postpone or suspend, for a reasonable period of time not to
exceed 90 days in any 12-month period, the filing, effectiveness or use of any
registration statement if the Company shall determine that any such filing or
the sale of any securities pursuant to such registration statement would, in the
good faith judgment of the Board of Directors of the Company, (i) materially
impede, delay or interfere with any pending or proposed financing, acquisition,
corporate reorganization or other similar transaction involving the Company for
which the Board of Directors of the Company has authorized negotiations, (ii)
adversely impair the consummation of any pending or proposed material offering
or sale of any class of securities by the Company, or (iii) require disclosure
of material nonpublic information that, if disclosed at such time, would be
materially harmful to the interests of the Company and its stockholders.

           1.4   Information from Stockholders.  It shall be a condition
                 -----------------------------
precedent to the obligations of the Company to take any action pursuant to this
Section 1 with respect to the Registrable Securities of a Stockholder that such
Stockholder shall furnish to the Company the information requested on Appendix
                                                                      --------
1.4 hereto, which shall include such information regarding himself, herself or
---
itself, the Registrable Securities held by him, her or it, and the intended
method of disposition of such securities, and such other information as shall be
reasonably requested by the Company and required to effect the registration of
the Registrable Securities.

           1.5   Expenses of Registration.  All expenses related to the
                 ------------------------
preparation and filing of the registration statement in respect of the
Registrable Securities, except underwriting discounts (if any) or commissions,
but including (without limitation) all registration, filing and qualification
fees, printers' and accounting fees, and fees and disbursements of counsel for
the Company shall be borne by the Company; provided, however, that the Company
                                           -----------------
shall not be required to pay any broker's, legal or accounting fees incurred by
any Stockholders.

           1.6   Assignment of Registration Rights.  The right to cause the
                 ---------------------------------
Company to register Registrable Securities pursuant to this Agreement may only
be assigned to a Permitted Transferee and the Stockholder assigning such rights
promptly notifies the Company of such assignment.

           1.7   Indemnification.  In the event any Registrable Securities are
                 ---------------
included in a registration statement under this Section 1:

                 (a) Each Stockholder will, if Registrable Securities held by
such Stockholder are included in the securities as to which such registration is
being effected, indemnify and hold harmless the Company, each of its directors,
each of its officers, each person, if any, who controls the Company within the
meaning of the Act, any other Stockholder selling securities in such
registration statement and any controlling person of any such Stockholder
against any losses, claims, damages, or liabilities (joint or several) to which
any of the foregoing persons may become subject, under the Act or the 1934 Act
or other Federal or state law, insofar as such losses, claims, damages or
liabilities (or actions in respect thereto) arise out of or are based upon any
of the following statements, omissions or violations (collectively, a
"Violation"): (i) any untrue statement or alleged untrue statement of a material
fact contained in such registration statement, including any preliminary
prospectus or final prospectus contained

                                       4

<PAGE>

therein or any amendments or supplements thereto, (ii) any omission or alleged
omission to state therein a material fact required to be stated therein, or
necessary to make the statements therein not misleading, or (iii) any violation
or alleged violation by the Company of the Act, the 1934 Act, any rule or
regulation promulgated under the Act or the 1934 Act or other Federal or state
law, in each case to the extent that such Violation is a result of the reliance
on any written information furnished by Stockholder for inclusion in such
registration; and the applicable Stockholders will pay, as suffered or incurred,
any legal or other expenses suffered or incurred by any person intended to be
indemnified pursuant to this subsection 1.7(a) in connection with investigating
or defending any such loss, claim, damage, liability, or action; provided,
                                                                 --------
however, that the indemnity agreement contained in this subsection 1.7(a) shall
-------
not apply to amounts paid in settlement of any such loss, claim, damage,
liability or action if such settlement is effected without the consent of
Stockholder, which consent shall not be unreasonably withheld; provided, that,
                                                               --------  ----
in no event shall any indemnity under this subsection 1.7(a) exceed the net
proceeds from the offering received by such Stockholder.

                 (b) The Company will indemnify and hold harmless each
Stockholder whose Registrable Securities were included in the securities as to
which a registration was effected, as well as each such Stockholder's officers,
directors, partners, legal counsel and persons controlling such Stockholder,
against any losses, claims, damages, or liabilities (joint or several) to which
any of the foregoing persons may be subject, under the Act or the 1934 Act or
other Federal or state law, insofar as such losses, claims, damages or
liabilities (or actions in respect thereto) arise out of or are based upon any
Violation to the extent that such Violation is based on any untrue statement or
omission or alleged untrue statement or omission made in reliance upon and in
conformity with any written information furnished by the Company in an
instrument duly executed by such Stockholder.

                 (c) Promptly after receipt by an indemnified party under this
Section 1.7 of notice of the commencement of any action (including any
governmental action), such indemnified party will, if a claim in respect thereof
is to be made against any indemnifying party under this Section 1.7, deliver to
the indemnifying party a written notice of the commencement thereof and the
indemnifying party shall have the right to participate in at the indemnifying
party's expense, and, to the extent the indemnifying party so desires, jointly
with any other indemnifying party similarly noticed, to assume the defense
thereof with counsel mutually satisfactory to the parties at the indemnifying
party's expense; provided, however, that an indemnified party (together with all
                 --------  -------
other indemnified parties which may be represented without conflict by one
counsel) shall have the right to retain one separate counsel, with the fees and
expenses to be paid by the indemnifying party, if representation of such
indemnified party or parties, as the case may be, by the counsel retained by the
indemnifying party would be inappropriate due to actual or potential conflicts
of interests between such indemnified party and any other party represented by
such counsel in such proceeding. No indemnifying party, in defense of any such
claim or litigation, shall, except with the consent of each indemnified party,
consent to entry of any judgement or enter into any settlement which does not
include as an unconditional term thereof the giving by the claimant or plaintiff
to the indemnified party of a release from all liability in respect to such
claim or litigation.

                 (d) If the indemnification provided for in this Section 1.7 is
held by a court of competent jurisdiction to be unavailable to an indemnified
party with respect

                                       5

<PAGE>

to any loss, liability, claim, damage, or expense referred to therein, then the
indemnifying party, in lieu of indemnifying such indemnified party hereunder,
shall contribute to the amount paid or payable by such indemnified party as a
result of such loss, liability, claim, damage, or expense in such proportion as
is appropriate to reflect the relative fault of the indemnifying party on the
one hand and of the indemnified party on the other in connection with the
statements or omissions that resulted in such loss, liability, claim, damage, or
expense as well as any other relevant equitable considerations. The relative
fault of the indemnifying party and of the indemnified party shall be determined
by reference to, among other things, whether the untrue or alleged untrue
statement of a material fact or the omission to state a material fact relates to
information supplied by the indemnifying party or by the indemnified party and
the parties' relative intent, knowledge, access to information, and opportunity
to correct or prevent such statement or omission. Notwithstanding the provisions
of this paragraph (d), no Stockholder shall be required to contribute any amount
in excess of the amount of net proceeds received by such Stockholder from the
sale of such Stockholder's Registrable Securities. Moreover, no person or entity
guilty of fraudulent misrepresentation within the meaning of Section 11(f) of
the Act shall be entitled to contribution from any person or entity that was not
guilty of such fraudulent misrepresentation.

                 (e) The obligations of each Stockholder under this Section 1.7
shall survive the completion of any offering of Registrable Securities in a
registration statement under this Agreement.

                 (f) Notwithstanding the foregoing, to the extent that the
provisions on indemnification and contribution contained in an underwriting
agreement (if any) entered into in connection with the underwritten public
offering are in conflict with the foregoing provisions, the provisions in the
underwriting agreement shall control.

           1.8   Termination of Registration Rights.  The registration rights
                 ----------------------------------
provided in this Section 1 shall terminate on August 31, 2003 or, as to any
Stockholder, such earlier time at which all of the Registrable Securities owned
by such Stockholder have been held for the necessary holding period under Rule
144 and all shares of Registrable Securities held by such Stockholder may be
sold pursuant to Rule 144 in any single three (3) month period. Upon the
termination of registration rights pursuant to this Section 1.8, the Company
shall have the right to withdraw the registration statement, or any portion
thereof, covering the Registrable Securities held by such Stockholder.

           1.9   Reports Under Securities Exchange Act of 1934.  With a view to
                 ---------------------------------------------
making available to the Stockholders the benefits of Rule 144 promulgated under
the Act and any other rule or regulation of the SEC that may at any time permit
a Stockholder to sell securities of the Company to the public without
registration or pursuant to a registration on Form S-3, the Company agrees to:

                 (a) Make and keep public information available, as those terms
are understood and defined in Rule 144;

                 (b) File with the SEC in a timely manner all reports and other
documents required of the Company under the Act and the 1934 Act; and

                                       6

<PAGE>

                 (c) Furnish to any Stockholder, so long as the Stockholder owns
any Registrable Securities, forthwith upon written request (i) a written
statement by the Company that it has complied with the reporting requirements of
Rule 144, the Act and the 1934 Act, (ii) a copy of the most recent annual or
quarterly report of the Company and such other reports and documents so filed by
the Company, and (iii) such other information as may be reasonably requested in
availing any Stockholder of any rule or regulation of the SEC which permits the
selling of any such securities without registration or pursuant to Form S-3.

        2. Miscellaneous.
           -------------

           2.1   General.  Nothing in this Agreement, express or implied, is
                 -------
intended to confer upon any party other than the parties hereto any rights,
remedies, obligations, or liabilities under or by reason of this Agreement,
except as expressly provided in this Agreement.

           2.2   Governing Law; Forum.  This Agreement shall be governed by and
                 --------------------
construed under the laws of the State of Delaware without giving effect to the
conflicts of laws principles thereof. In any action between the parties hereto
arising out of or relating to this Agreement or any of the transactions
contemplated by this Agreement: (a) each of the parties irrevocably and
unconditionally consents and submits to the exclusive jurisdiction and venue of
either (i) the state courts located in San Francisco County, California or
Johnson County, Kansas, or (ii) the United States District Court for the
Northern District of California or the District of Kansas, (b) each of the
parties irrevocably consents to service of process by first class certified
mail, return receipt requested, postage prepaid and (c) each of the parties
irrevocably waives the right to a trial by jury.

           2.3   Counterparts.  This Agreement may be executed in two or more
                 ------------
counterparts, each of which shall be deemed an original, but all of which
together shall constitute one and the same instrument.

           2.4   Titles and Subtitles.  The titles and subtitles used in this
                 --------------------
Agreement are used for convenience only and are not to be considered in
construing or interpreting this Agreement.

           2.5   Notices.  Unless otherwise provided, any notice required
                 -------
or permitted under this Agreement (i) to be made to the Company shall be given
in writing to the Company or (ii) to be made to the Stockholders shall be given
in writing to the Stockholders' Representative, and such notice shall be deemed
effectively given upon facsimile (with confirmed receipt), or personal delivery
to the party to be notified at the address indicated for the Company or the
Stockholders' Representative on the signature page hereof, or at such other
address as such party may designate by ten (10) days' advance written notice to
the other party.

           2.6   Expenses.  If any action at law or in equity is necessary
                 --------
to enforce or interpret the terms of this Agreement, the prevailing party shall
be entitled to reasonable attorneys' fees, costs and necessary disbursements in
addition to any other relief to which such party may be entitled.

                                       7

<PAGE>

           2.7   Amendments and Waivers.  Any term of this Agreement may be
                 ----------------------
amended and the observance of any term of this Agreement may be waived (either
generally or in a particular instance and either retroactively or
prospectively), only with the written consent of the Company and the
Stockholders holding a majority of the Registrable Securities.

           2.8   Severability.  If one or more provisions of this Agreement are
                 ------------
held to be unenforceable under applicable law, such provision shall be excluded
from this Agreement and the balance of the Agreement shall be interpreted as if
such provision were so excluded and shall be enforceable in accordance with its
terms.

           2.9   Entire Agreement.  This Agreement constitutes the full and
                 ----------------
entire understanding and agreement between the parties with regard to the
subject hereof.

                  [Remainder of page intentionally left blank]

                                        8

<PAGE>

        IN WITNESS WHEREOF, the parties have executed this Registration Rights
Agreement as of the date first above written.

                               ACTUATE CORPORATION

                               By:   /s/ Daniel A. Gaudreau
                                   ---------------------------------------------
                                   Daniel A. Gaudreau
                                   President and Chief Financial Officer

                               Address: 701 Gateway Blvd.
                                        South San Francisco, California  94080

                               MICHAEL J. GASSMAN

                               /s/  Michael J. Gassman
                               -------------------------------------------------

                               Address: 12980 Metcalf Avenue, Suite 300
                                        Overland Park, Kansas  66213

                                       9

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