I would consider replacing the power supply if at all possible.
There is a small chance it could be the hard drive or the video card. But I don't think they are the culprit.
If at all possible, open the case and check connections. Make sure they are tight, also re-seat the memory (take it out and put it back in). Also make sure all of the PCI cards are snug. These things may help and may not.
If the above doesn't help, consider replacing the power supply if at all possible.
If you could provide some info about your computer it may help with some further things to try.
- OS (Operating System) - Windows XP Home/Pro, 98, 2000.
- Is it a Dell/Compaq/HP
- CPU Brand/Speed
- Amount of memory
Just some basics about the computer. If you don't know some of the stuff, there are a couple of utilities you can use to figure it out.
Hope some of these suggestions help.
Later,
luveyes
http://pcprogrammers.net