Computer shutdown from logonscreen

Hi
I'm trying to create a screensaver that will shutdown the computer
from the logon screen. I wan´t the computer to automatic shutdown
after an our if nobody is logged in on it. But the problem is
that the system privileges on the logon screen will not permit
the program to execute that task. Tried to add system to the
SeShutdownPrivileges with ntrights but it doesn´t work.
Any one got a clue?
Regards
Roland

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