If you are running Windows XP you can go to control panel>performance and maintenance>power options>advanced tab and tell it what to do. Good luck.
An older home computer was shut down when an unknowing repairman pulled the plug. Since that time the computer will not reboot to a normal windows o/s. It will boot to windows safe mode however if enticed by pressing F8...otherwise it runs thru it's Compac screen and the windows XP professional screen... goes blank and then shuts down..monitor with it..and restarts immediately to go thru that process forever. Once or twice in safe mode, I restored the computer and upon restart if i put it back into safe mode it would say the restore was successful, but it didn't resolve the continual reboot issue. We ran a group of diagnostics on all the hardware with a floppy called Microscope and it passed all the hardware tests. Once after changing a setting in safe mode to control error messages at start up i did get a fatal error message with the number c000021a and once that showed the computer halted.. no self reboot. i changed those options back in safe mode and it went away. Last night, frustrated I just shut the computer down..completely and walked away. Then within an hour, i heard it start itself back up to the infinate start up sequence until i shut it off at the power strip. Any suggestions out there?