<PAGE>   1
                                                                  EXHIBIT 10.125

                                                             1997 REVOLVING LOAN

                        SIXTH AMENDMENT TO LINE OF CREDIT
                          CREDIT AND SECURITY AGREEMENT

         THIS SIXTH AMENDMENT TO LINE OF CREDIT CREDIT AND SECURITY AGREEMENT
(this "Amendment") is made and entered into effective as of February 15, 2001
between CRESCENT REAL ESTATE EQUITIES LIMITED PARTNERSHIP, a Delaware limited
partnership (the "Lender") and CRESCENT OPERATING, INC., a Delaware corporation
(the "Borrower").

                                    RECITALS

         A. The parties executed that certain Line of Credit Credit and Security
Agreement dated as of May 21, 1997, as amended by that certain First Amendment
to Line of Credit Credit and Security Agreement dated as of August 11, 1998, by
that certain Second Amendment to Line of Credit Credit and Security Agreement
dated as of September 21, 1998, and by that certain Third Amendment to Line of
Credit Credit and Security Agreement dated as of March 11, 1999 (collectively,
the "Original Agreement"). All capitalized terms not otherwise defined in this
Amendment will have the same meaning as described in the Original Agreement.

         B. The parties executed that Fourth Amendment to Line of Credit Credit
and Security Agreement dated as of February 1, 2001, to defer the interest
payments that would otherwise be due on the first Business Day of February, May,
August and November 2000 until the first Business Day of February 2001; and the
parties executed that Fifth Amendment to Line of Credit Credit and Security
Agreement dated as of January 31, 2001, to defer until February 15, 2001, the
interest payments that would otherwise be due on the first Business Day of
February 2001 and on February 1, 2001. The Original Agreement, as amended by
that Fourth Amendment and by that Fifth Amendment, is called the "Amended
Original Agreement."

         C. The parties wish to further defer the aforementioned payments until
March 5, 2001.

         In consideration of the mutual covenants set forth herein, and for
other good and valuable consideration, the receipt and sufficiency of which are
hereby acknowledged, the parties hereto hereby agree as follows:

         1. Section 2.3. Section 2.3(c) of the Amended Original Agreement is
hereby amended by the addition of the following sentence to the end thereof:

         The Borrower and the Lender hereby agree that the interest that would
         otherwise be due on the first Business Day of February, May, August and
         November 2000 and of February 1, 2001 shall be deferred until, and
         shall be due on, March 5, 2001.

         2. Remainder of Amended Original Agreement. Except as amended hereby,
the Amended Original Agreement shall continue in full force and effect in the
form that was effective immediately before the execution of this Amendment.



                                       1
<PAGE>   2

                                                             1997 REVOLVING LOAN

         3. Counterparts. This Amendment may be executed in any number of
counterparts, all of which taken together shall constituted one and the same
document.

         4. Binding Effect. This Amendment shall be binding upon and inure to
the benefit of the respective successors and assigns of the parties hereto.

         5. Governing Law and Severability. This Amendment shall be governed by
and construed in accordance with the laws of the State of Texas. Whenever
possible, each provision hereof shall be interpreted in such manner as to be
effective and valid under applicable law.

         IN WITNESS WHEREOF, the parties below have executed this Amendment
effective as of the date first written above.


                                        CRESCENT OPERATING, INC.


                                        By:
                                            ------------------------------------
                                            Name:
                                                  ------------------------------
                                            Title:
                                                   -----------------------------



                                        CRESCENT REAL ESTATE EQUITIES
                                        LIMITED PARTNERSHIP

                                        By: Crescent Real Estate Equities, Ltd.,
                                            its general partner


                                               By:
                                                   -----------------------------
                                                   Name:
                                                         -----------------------
                                                   Title:
                                                          ----------------------


                                       2