Document:

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                                                                    EXHIBIT 4.1

Kontron Embedded Computers AG
Oskar-von-Miller-Strasse 1
85386 Eching, Germany

                                 LOAN AGREEMENT

Kontron Embedded Computers AG hereby agrees to decrease the interest rate for
the last credit, effective July 1st, 2002 from 11% to 10%.

The interest rate is 10% p.a., calculated on a daily basis, payable 15 days
after the end of each month.

Each payment (repay of the loan and interest) has to be done in Euro.

The loan agreement is valid from 21st of July 2001, and due and payable by the
1st of July 2011.

May 17th, 2002

/s/ Hannes Niederhauser                                /s/ Thomas Sparrvik
-----------------------------                          ------------------------
Hannes Niederhauser                                    Thomas Sparrvik
Kontron Embedded Computers AG                          Kontron Mobile Computing<PAGE>

                                                                    EXHIBIT 10.1

                               FOURTH AMENDMENT TO
                      AMENDED AND RESTATED CREDIT AGREEMENT

         THIS FOURTH AMENDMENT TO AMENDED AND RESTATED CREDIT AGREEMENT is dated
November 13, 2002 but effective as of September 30, 2002 (the "Fourth
Amendment"), among PETROQUEST ENERGY, L.L.C., a Louisiana limited liability
company (the "Borrower"), PETROQUEST ENERGY, INC., a Delaware corporation (the
"Guarantor"), the LENDERS, and HIBERNIA NATIONAL BANK, a national banking
association, individually as a Lender and as Administrative Agent.

                                    RECITALS:

         1. The parties hereto are the parties to that certain Amended and
Restated Credit Agreement dated as of May 11, 2001, as amended by First
Amendment thereto dated as of July 20, 2001, as amended by Second Amendment
thereto dated as of December 24, 2001, and as amended by Third Amendment thereto
dated as of March 1, 2002 (as so amended, the "Agreement"), pursuant to which
the Lenders established in favor of the Borrower a revolving line of credit.

         2. The purpose of this Fourth Amendment is to evidence certain changes
to the Agreement.

         3. Capitalized terms used herein which are defined or used in the
Agreement are used herein with such meanings, except as may be otherwise
expressly provided in this Fourth Amendment.

         NOW, THEREFORE, THE PARTIES HERETO, IN CONSIDERATION OF THE MUTUAL
COVENANTS HEREINAFTER SET FORTH AND INTENDING TO BE LEGALLY BOUND HEREBY, AGREE
AS FOLLOWS:

         A. AMENDMENT TO DEFINITIONS.

         1. The definition of the term "Consolidated Current Assets" in the
Agreement is hereby deleted and restated as follows:

         "CONSOLIDATED CURRENT ASSETS" shall mean the total of Guarantor's
         consolidated current assets, including the amounts available for
         borrowing under the Borrowing Base Amount, determined in accordance
         with GAAP. Effective September 30, 2002, the Guarantor's current assets
         on that date will include the net proceeds from the sale of shares of
         the Guarantor's common stock that Guarantor receives during the period
         commencing October 1, 2002 and ending on November 30, 2002. Current
         assets will not include the effects, if any, of marking to market
         Hedging Agreements pursuant to SFAS No. 133.

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         2. The definition of the term "Indebtedness" in the Agreement is hereby
deleted and restated as follows:

         "INDEBTEDNESS" shall mean, at any time, all obligations, indebtedness,
         and liabilities, whether now existing or arising in the future, of the
         Borrower to any Lender pursuant to a Hedging Agreement or other
         commodity hedge or price management transaction permitted by Section
         13.10 of this Agreement (including all renewals, extensions,
         modifications, and substitutions thereof or therefor) and all
         cancellations, buy backs, reversals, terminations, or assignments of
         such permitted Hedging Agreements or permitted commodity hedge or price
         management transactions, the Reimbursement Obligations, obligations of
         the Borrower under Rate Management Transactions (including all
         renewals, extensions, modifications, and substitution thereof and
         therefor) and all cancellations, buy backs, reversals, terminations, or
         assignments of Rate Management Transactions, and the indebtedness of
         the Borrower evidenced by the Notes executed by the Borrower pursuant
         to this Agreement, in principal, interest, costs, expenses and
         reasonable attorneys' fees and all other fees and charges, together
         with all commitment fees and other indebtedness and costs and expenses
         for which the Borrower is responsible under this Agreement or under any
         of the Related Documents. In addition, the word "Indebtedness" also
         includes, any and all other loans, extensions of credit, obligations,
         debts and liabilities of the Borrower, plus interest thereon, that may
         now and in the future be owed to or incurred in favor of the Lenders
         and the Administrative Agent, as well as all claims by the Lenders and
         the Administrative Agent against the Borrower, whether existing now or
         later; whether they are voluntary or involuntary, due or to become due,
         direct or indirect or by way of assignment, determined or undetermined,
         absolute or contingent, liquidated or unliquidated; whether the
         Borrower may be liable individually or jointly with others, of every
         nature and kind whatsoever, in principal, interest, costs, expenses and
         reasonable attorneys' fees and all other fees and charges; whether the
         Borrower (or any one or more of them) may be obligated as principal
         obligor, guarantor, surety, accommodation party or otherwise.

         3. The definition of the term "Quarterly Reduction" in the Agreement is
hereby deleted and restated as follows:

         "QUARTERLY REDUCTION" shall mean each reduction to the Borrowing Base
         Amount established by the Required Lenders based on each scheduled and
         unscheduled redetermination of the Borrowing Base Amount. The Quarterly
         Reduction will be made

    Fourth Amendment to Amended and Restated Credit Agreement -- Page 2 of 6

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         on January 31, April 30, July 31, and October 31 of each year. The
         Quarterly Reduction will be $5,000,000.00 commencing on January 31,
         2003, unless redetermined by the Required Lenders. The Administrative
         Agent will promptly notify the Borrower of any change in the Quarterly
         Reduction as determined from time to time by the Required Lenders.

         4. The following new definition is hereby added to the Agreement:

         "FOURTH AMENDMENT" shall mean that certain Fourth Amendment to Amended
         and Restated Credit Agreement effective September 30, 2002, among the
         Borrower, the Guarantor, the Lenders, and the Administrative Agent.

         B. BORROWING BASE AMOUNT REDETERMINATION. The Agreement is hereby
amended to reflect that as of September 30, 2002, the Borrowing Base Amount is
$25,000,000.00. The parties also acknowledge that the next regularly scheduled
semi-annual determination of the Borrowing Base Amount will take effect on March
31, 2003.

         C. REVISION TO NEGATIVE COVENANTS. Section 13.5 (Debts, Guaranties, and
Other Obligations) is hereby deleted and restated as follows:

         SECTION 13.5. DEBTS, GUARANTIES AND OTHER OBLIGATIONS. The Borrower and
         the Guarantor, without the prior written consent of the Majority Banks,
         will not incur, create, assume or in any manner become or be liable in
         respect of any indebtedness, guaranties, and/or other obligations,
         direct or contingent, except for:

         (a) The Indebtedness to the Lenders under this Agreement;

         (b) Trade payables or operating and facility leases from time to time
         incurred in the ordinary course of business;

         (c) Non-Recourse Indebtedness not to exceed $25,000,000.00 at any time
         outstanding;

         (d) Taxes, assessments or other government charges which are not yet
         due or are being contested in good faith by appropriate action promptly
         initiated and diligently conducted, if such reserve as shall be
         required by generally accepted accounting principles shall have been
         made therefore;

         (e) The outstanding indebtedness (as of the date of this Agreement)
         under the HEIC Facility;

         (f) Existing debt (as of the date of this Agreement) of the Borrower to
         Linc Monex; or

    Fourth Amendment to Amended and Restated Credit Agreement -- Page 3 of 6

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         (g) The Guarantor's guaranty of the Borrower's indebtedness,
         obligations, and liabilities to any of the Lenders pursuant to Hedging
         Agreements and/or commodity hedge or price management transactions
         permitted by the Agreement, as amended by the Fourth Amendment.

         D. CONFIRMATION OF COLLATERAL DOCUMENTS. It is the intention of the
parties that all of the liens, privileges, priorities, and equities existing and
to exist under and in accordance with the terms of the Loan Documents are hereby
renewed, extended, and carried forward as security for the Loans and the
Indebtedness (as defined in paragraph A above). Further, the parties agree and
acknowledge that the Guaranty shall continue to secure the payment of the
Indebtedness (as defined in paragraph A above) of the Borrower to the Lenders,
including the indebtedness of the Borrower under the Revolving Notes.

         E. NO DEFAULT REPRESENTATION. On and as of the date hereof, and after
giving effect to this Fourth Amendment, the Borrower and the Guarantor reaffirm
and restate the representations and warranties set forth in the Agreement and
the Loan Documents. Further, the Borrower and the Guarantor also represent and
warrant that as the date hereof and after giving effect to this Fourth
Amendment, no uncured or unwaived Default has occurred and is continuing under
the Agreement, as amended by this Fourth Amendment.

         F. CONDITIONS PRECEDENT. The obligation of the Lenders to make the
Loans remains subject to the conditions precedent set forth in the Agreement and
the following conditions precedent: The Administrative Agent's receipt of (i)
this Fourth Amendment executed by the Borrower and the Guarantor; (ii) certified
resolutions by the Guarantor (on behalf of itself and as the sole member of the
Borrower), in form and substance satisfactory to the Administrative Agent; (iii)
all amendments, supplements, and/or restatements pertaining to the Collateral
Documents that may be required by the Administrative Agent or its counsel; and
(iv) the sum of $22,500.00, representing a $7,500.00 work fee for each Lender.

         G. WAIVER OF DEFENSES. In consideration of the Lenders' execution of
this Fourth Amendment, the Borrower and the Guarantor do hereby irrevocably
waive any and all claims and/or defenses to payment on any Indebtedness owed by
any of them to the Lenders and/or the Administrative Agent that may exist as of
the date of execution of this Fourth Amendment.

         H. AMENDMENTS. THE AGREEMENT AND THIS FOURTH AMENDMENT ARE CREDIT OR
LOAN AGREEMENTS AS DESCRIBED IN LA. R.S. 6:SECTION 1121, ET SEQ. THERE ARE NO
ORAL AGREEMENTS BETWEEN PARTIES TO THIS FOURTH AMENDMENT. THE AGREEMENT, AS
AMENDED BY THIS FOURTH AMENDMENT, SETS FORTH THE ENTIRE AGREEMENT OF THE PARTIES
WITH RESPECT TO THE SUBJECT MATTER HEREOF AND SUPERSEDES ALL PRIOR WRITTEN AND
ORAL UNDERSTANDINGS BETWEEN THE ADMINISTRATIVE AGENT, THE LENDERS, THE BORROWER,
AND THE GUARANTOR WITH RESPECT TO THE MATTERS HEREIN SET FORTH. THE AGREEMENT,
AS AMENDED BY THIS FOURTH AMENDMENT, MAY NOT BE MODIFIED OR AMENDED EXCEPT BY A
WRITING SIGNED AND DELIVERED BY THE

    Fourth Amendment to Amended and Restated Credit Agreement -- Page 4 of 6

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BORROWER, THE GUARANTOR, THE LENDERS, AND THE ADMINISTRATIVE AGENT.

         I. GOVERNING LAW: COUNTERPARTS. This Fourth Amendment shall be governed
by and construed in accordance with the laws of the State of Louisiana. This
Fourth Amendment may be executed in any number of counterparts, all of which
counterparts, when taken together, shall constitute one and the same document.

         J. CONTINUED EFFECT. Except as expressly modified herein, the Agreement
as amended by this Fourth Amendment, shall continue in full force and effect.
The Agreement, as amended by this Fourth Amendment, is hereby ratified and
confirmed by the parties hereto.

         IN WITNESS WHEREOF, the parties hereto have caused this Fourth
Amendment to be executed and delivered as of the date hereinabove provided by
the authorized officers each hereunto duly authorized.

                                BORROWER:

                                PETROQUEST ENERGY, L.L.C.
                                A LOUISIANA LIMITED LIABILITY COMPANY

                                BY PETROQUEST ENERGY, INC., A DELAWARE
                                CORPORATION, AS SOLE MEMBER

                                BY:  /s/ ALFRED J. THOMAS, II
                                     ----------------------------------------
                                NAME:  ALFRED J. THOMAS, II
                                       --------------------------------------
                                TITLE:  PRESIDENT AND CHIEF OPERATING OFFICER
                                        -------------------------------------

                                GUARANTOR:

                                PETROQUEST ENERGY, INC.
                                A DELAWARE CORPORATION

                                BY:  /s/ ALFRED J. THOMAS, II
                                     ----------------------------------------
                                NAME:  ALFRED J. THOMAS, II
                                       --------------------------------------
                                TITLE:  PRESIDENT AND CHIEF OPERATING OFFICER
                                        -------------------------------------

    Fourth Amendment to Amended and Restated Credit Agreement -- Page 5 of 6

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                                 AGENT:

                                HIBERNIA NATIONAL BANK, AS ADMINISTRATIVE AGENT

                                BY:  /s/ DAVID R. REID
                                     ----------------------------------------
                                NAME:  DAVID R. REID
                                TITLE: SENIOR VICE PRESIDENT

                                LENDERS:

                                ROYAL BANK OF CANADA

                                BY:  /s/ LORNE GARTNER
                                     ----------------------------------------
                                NAME:  LORNE GARTNER
                                       --------------------------------------
                                TITLE: VICE PRESIDENT
                                       --------------------------------------

                                UNION BANK OF CALIFORNIA, N.A.

                                BY:  /s/ DAMIEN MEIBURGER
                                     ----------------------------------------
                                NAME:  DAMIEN MEIBURGER
                                       --------------------------------------
                                TITLE: SENIOR VICE PRESIDENT
                                       --------------------------------------

                                HIBERNIA NATIONAL BANK

                                BY:  /s/ DAVID R. REID
                                     ----------------------------------------
                                NAME:  DAVID R. REID
                                TITLE: SENIOR VICE PRESIDENT

    Fourth Amendment to Amended and Restated Credit Agreement -- Page 6 of 6

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