Reboot at Logoff

I determine how long a computer has been up since the last reboot. In order to be as non-intrusive as I can, I want to reboot the computer when the user logs off, when it exceeds the amount of time I have specified. As we know, at logoff or shutdown, programs will not run as the computer is in a “logoff” or “shutdown” state and will not allow it. Does anyone know a way around this?