Shoutbox

Hi,

There can be many causes for the computer restarting and figuring it out may take some time and work.  You didn't say what version of Windows you have, so I am going to assume XP.

The first thing I'd like you to try is click the "Start" button, right-click "My Computer", click "Properties", click the "Advanced" tab, and then click "Settings" under "Startup and Recovery".  Under "System Failure", uncheck the "Automatically restart" check box if it is checked.  Click "Ok" twice to save the change.

This by itself won't fix anything, but will stop Windows from automatically rebooting on blue screen error messages (often called "BSOD" -- blue screen of death).  On a fast computer, this happens so quickly you may never even see any blue on the screen. 

If this is the case, next time the error message will stay up until you restart the computer yourself.  Write down what it says, post it, and we will go from there.

If the computer continues to reboot without any sort of message, it is almost certainly a hardware problem, possibly overheating as someone suggested.  Take the cover off your computer, turn it on and verify that all fans you can see inside are spinning. 

Also, the power supply has a fan in it too, usually blowing air out in the back -- make sure that is working as well (you should be able to feel the air flow on your hand).