My Windows XP computer keeps crashing about every 2 hours. The system on light is still on but none of the fans are running and there is no video or sound. If I press the restart or shutdown buttens, nothing happens and the only way to make it useable again it to un-plug it for about 5 seconds and plug it back in.

Hello alastairpat,

The most likely, and infact highly likely cause of this is a faulty power supply, so you will probably need to buy new.

- Check the fan is working at the back of the Power Supply.
- If you have added any new devices to the power supply, make sure the power supply has enough power to support these devices, click on: eXtreme Power Supply Calculator - What Power Supply Do I Need

Agreed,

Most likely cause is power supply

But if it's every 2 hours? It might be over heating? hrmmmm...