Deep Freeze Unfreezer works on all versions of Deep Freeze 9X/2000/XP to thaw the system back to an unfrozen state without knowing the password.

Rename deepunfreezer.bak to deepunfreezer.exe

Faronics Deep Freeze - Home Page
http://www.faronics.com/html/deepfreeze.asp

Deep Freeze Unfreezer - Home Page
http://usuarios.arnet.com.ar/fliamarconato/pages/edeepunfreezer.html

First you must acquire DebugPrivileges (removed by Deep Freeze):

Method 1:

by escalating to NT_AUTHORITY (the System account) using Task Scheduler from the command line:

1) at 11:23pm /interactive taskmgr.exe (substitute the correct time)
2) End Task explorer.exe
3) File / New Task (Run...) explorer.exe to launch the explorer shell under the System account which has Debug Privileges
4) Run Deep Unfreezer from the System account

OR,

Method 2:

use ntrights.exe from the Windows Server 2003 Resource Kit, a free download, http://tinyurl.com/6p6cy to grant yourself the SeDebugPrivilege.
Syntax: ntrights -u Users +r SeDebugPrivilege
If you use ntrights, you must logoff and logon again before the new privilege takes effect.

Then run Deep Unfreezer, View Status, click on the Boot Thawed button, Save Status, and restart the machine.

Voila!! THAWED.

A similar technique can be used to remove Deep Freeze Evaluation version by forwarding the date on a machine past 60-days which will expire Deep Freeze, causing it to restart in thawed mode and allowing uninstall. Here's how:

1) Switch to the System account, as described above
2) Double-click the time in the system tray
3) Forward the date past 60-days
4) Restart in thawed mode
5) Use a DeepFreezeSTDEval.exe to uninstall Deep Freeze. Deep Freeze is not uninstalled through Add/Remove Programs. It is uninstalled with the installation file, and ONLY with an installation file. Yes, the same file is used to install and uninstall. If you don't have it, download it here: 
Deep Freeze Evaluation - Trial Version
http://www.faronics.com/exe/DeepFreezeSTDEval.exe

Or, use ntrights.exe from the Windows Resource Kit to grant yourself the SeSystemtimePrivilege.
Syntax: ntrights -u Users +r SeSystemtimePrivilege
You must logoff and logon again for the new privilege to take effect.

On Deep Freeze v5.60.120.1347 (the newest version, released Oct-20-2005) simply rename frzstate2k.exe to anything else, then attach to DF5Serve.exe instead when you run Deep Unfreezer.