Customize "Logoff" button action

I have checked everywhere on the internet but cannot find answer to this question. Can anyone tell me how to change the action behind the Logoff button? We have to do this because we are serving several virtual windowsxp desktops. The users connect to the desktop using RDP, so, there is the "Shut down" button not available. We want, when a user logs off the virtual machine, that the machine logs off and restart again. (to remove changes to the drive using Steady State). We have tried to do this with a logoff script, but that is not working (the shutdown -r -t 00 process is killed by the logoff process.) Can anyone please help.

Acutally, the commands are hard coded inside \WINDOWS\System32\user32.dll. So to change the action while pressing the log off button you have to find the code inside of user32.dll and change it.

ExitWindowsEx(int uFlags, int dwReason)

Log Off: ExitWindowsEx(0, 0)
Log Off: ExitWindowsEx(4, 0) (force processes to terminate while
logging off)
Reboot: ExitWindowsEx(2, 0)
Shutdown: ExitWindowsEx(1, 0)

Thanks for the reply, but I wanted to know if this is supported by Microsoft or not? Do you have any other options available?

You can try to create a shortcut on the desktop to the shutdown.exe file and then modify the paramaters used in the target box on the general properties page of the shortcut. I have used to use this trick to force an older machine I had installed XP on to shutdown at a specified time.

I also have the need for a user to Reboot when the Logoff button is press or selected, what do I use to edit the .dll? I can see the some info with ResHacker but not the "ExitWindowsEx(0, 0)" I am trying to do this on a Xp Pro box. Thanks for the Help!