Directory Services Restore Mode Password

Here you go, straight from Technet article Q239803:

How to Change the Recovery Console Administrator Password on a Domain Controller

Shut down the domain controller on which you want to change the password.

Restart the computer (when the selection menu screen is displayed during the restart process, press F8 to view advanced startup options).

Click the Directory Service Restore Mode option.

After you successfully log on, change the local Administrator password using either of the following methods:

At a command prompt, type the following command:

net user administrator *
OR
Use the Local User and Groups snap-in (Lusrmgr.msc) to change the Administrator password.

Shut down and restart the computer."

The * should be replaced by the password you want to use, I believe!

Here is the URL:
http://support.microsoft.com/default.aspx?scid=kb;en-us;Q239803
(please remove any spaces)

Hope this helps