<PAGE>

                                                                   EXHIBIT 10.48
PROMISSORY NOTE


$500,000                                                         January 8, 2001
                                                          San Carlos, California



         FOR VALUE RECEIVED, the undersigned Borrower promises to pay to
Liberate Technologies, Inc. ("Liberate") at its principal executive offices the
principal sum of five hundred thousand dollars ($500,000), together with
interest from the date of this Note on the unpaid principal balance, upon the
terms and conditions specified below.

         1.     TERM AND AMORTIZATION. The principal balance of this Note,
together with interest accrued and unpaid to date, shall be due and payable at
the close of business on the second anniversary of the date of this Note. The
entire principal balance of this Note, together with interest accrued and unpaid
to date, shall be due and payable 60 days after the Borrower's employment with
Liberate terminates.

         2.     RATE OF INTEREST. Interest shall accrue under this Note on any
unpaid principal balance at the rate of 5.90% per annum, compounded annually.

         3.     PREPAYMENT. Prepayment of principal and interest may be made at
any time, without penalty.

         4.     NOTE DUE AND PAYABLE. The entire unpaid principal sum and unpaid
interest under this Note shall become immediately due and payable upon:

         (a)    The failure of the Borrower to pay when due the principal
     balance and accrued interest on this Note and the continuation of such
     default for more than 30 days; or

         (b)    The insolvency of the Borrower, the commission of an act of
     bankruptcy by the Borrower, the execution by the Borrower of a general
     assignment for the benefit of creditors, or the filing by or against the
     Borrower of a petition in bankruptcy or a petition for relief under the
     provisions of the federal bankruptcy act or another state or federal law
     for the relief of debtors and the continuation of such petition without
     dismissal for a period of 90 days or more.

         5.     PERSONAL LIABILITY. The Borrower shall be personally liable for
payment of this Note.

         6.     COLLECTION. If action is instituted to collect this Note, the
Borrower promises to pay all reasonable costs and expenses (including reasonable
attorney's fees) incurred in connection with such action.

         7.     WAIVER. No previous waiver and no failure or delay by Liberate
or the Borrower in acting with respect to the terms of this Note shall
constitute a waiver of any breach,
<PAGE>

default, or failure of condition under this Note or the obligations secured
thereby. A waiver or modification of any term of this Note or of any of the
obligations secured thereby must be made in writing and signed by a duly
authorized officer of Liberate and shall be limited to the express terms of such
waiver.

         The Borrower hereby expressly waives presentment and demand for payment
at such time as any payments are due under this Note.

         8.     CONFLICTING AGREEMENTS. In the event of any inconsistencies
between the terms of this Note and the terms of any other document related to
the loan evidenced by this Note, the terms of this Note shall prevail.

         9.     GOVERNING LAW. This Note shall be construed in accordance with
the laws of the State of California, and the parties stipulate to the personal
jurisdiction of the state and federal courts for the county of San Mateo,
California.


                                         Name:  Coleman Sisson


                                         /s/ Coleman Sisson
                                         ---------------------------------------
                                         Signature of Borrower
                                         [Confidential Data]

                                       2