A dust and lint layer on some cpu or other heatsink. An aging power supply or the infamous bad motherboard capacitors.
Then again... a classic. "Bad RAM."
There is not enough clues here to do anymore but guess.
-> Software? How about this one. You wrote XP. That one gets a WORM on install if you connect to the internet. Tell what you do to stop that. Hint: It's not an antivirus.
My computer started going crazy, crossed files, all kinds of error messages. I decided to format the hard drive and reinstall Windows XP. The process started smoothly until it reboots. The hard disk formats ok, the files get loaded ok, then it states it needs to reboot. Then I get a disk error message. I press, cntrl, alt, delete and the same error message repeats itself.
Here is what I have done to try to resolve the problem. I have installed a new hard drive. I have used 2 different Windows install cd's. I have also used 2 different cd rom drives. Same message. Do you think it's a motherboard issue, a bios issue, or something else? Any advice would be appreciated. May be time for a new computer.
Specs. Dell Dimension 8300, 1.4 pentium processor, 256 ram, soundblaster live audio, Nvidea graphics card, Windows XP home.