PC Keeps Restarting?

Sorry about my English. I think the power button is broken, like it is always pressed all the time. So when you turn it on, then it turns off in several seconds later. Consult the dealer.

Maybe a virus. Get a Linux live cd or something and back up your data. Then reinstall Windows.

if the RAM is the source of problem......you should see a blue screen and an error message like........page fault, memory location xxx corrupt,etc virus is a small possibilitiy but cant be ruled out........... OS corruption is more likely the source of problem.........

It is not because of the virus it is restarting but due to anti virus. becasue after u install the antivirus especially Norton and if your pc already has virus in it if you restart pc after Norton installation then virus is found and keeps restarting. Try to reset BIOS. If so and if issue remains same just take out h/w and keep them again and if still isuue is same try with other HDD or install frest OS and install antivirus immediately.

Unplug the power cables, and try. I know it's risky, but with us it worked. If you don't want to do that (I don't blame you lol) than take it to a service. That is some scary situation...

you must a re install window xp. your computer is deadly,

This could be the result of many, many things. Could be a virus, spyware, or even a program that was recently installed. Use your Windows XP cd that came with your computer and run a REPAIR. Insert the CD and let it boot, and attempt to install windows. DO NOT USE THE RECOVERY CONSOLE, that is not what you want. When you try to reinstall windows, it will ask you if you want to repair, answer YES. You will need to install all updates and service packs and IE 7 again if that is what you were running. All of your applications and data should be fine.

Reinstall Windows. If it still happens then it could be dodgey RAM so swap that out. If it still happens take out each card you have connected one by one.

Could be a virus. You could also try disconnecting certain parts in the computer to try and isolate the problem. If the restarts are happening at random times, it could be a heat or power supply problem.