Re: pc - turnoff
The top messages are right, but in most cases, it may be a cause of a virus trying to reboot your computer at once. May be it is hiding somewhere in your hard disk drive...
If it tries to shutdown for just about 50 seconds: Its a problem, that virus loads and reloads each time you boot your PC (Try to back-up your files on a seperate drive or disk (optical disks would do) and reformat your infected hard disk.) That would fix it (It happened to my friend before)