I posted this last week some time and got some good answers back. I have a amd duron 800 process with windows 2000. I was not getting any response at all on boot other than fan and lights. I did a bare bones boot after re seeding the process and it booted fine. I did several other boots and it seemed like that had fixed the problem. But after having the system running for a few hours, the keyboard and mouse locked and had to do a power off. When I attempted to power back on, I am now right back where I was last week. Could this be the processor overheating or could it possibly be just going bad? Or does it sound more like the power supply?

this is the origonal thread
http://www.pcguide.com/vb/showthread.php?s=&threadid=19355

I think everyone pretty much covered what the problem could be..
PSU..MOBO...Processor.. it is a hardware problem so you will need to start replacing parts to find out..

I would do the cheapest route first PSU and go from there..

And also ask yourself is the machine worth putting a few hundred into it? or spring for a whole new system? Depending on how old the system is??

It may be helpful to say how you were cooling the CPU, it certainly sounds like you could have burned it up given the pattern you describe.

Budfred