PC shuts down during Win2K Boot up

I have a Win2K machine that shuts down at the
exact same point every time. Right when the
Windows 2000 Splash screen comes up and the
status bar hits about 1/3 of the way, the
machine automatically powers off. It literally
just shuts off. I have tried it numerous times
and the same thing happens. I have reinistalled
and after it reboots on the install it gets to the
same point and just turns off. Does iany one have any idea as to what could be wrong?