Natasha writes in with a troubleshooting question:
Question:The computer turns on and the fan goes on but as soon as it’s ready to bring the log on window up, the computer restarts all over again. What should I do?
Answer: Unfortunately there can be many reasons a computer will restart itself. It can be hardware or software related.
The first thing you should do is to see if its software related. Try and start the computer in Safe Mode to see if you can at least boot it up.
If you can get into Safe Mode then you can see if there are any malicious programs trying to start when you boot up. Use msconfig and go to the startup tab and uncheck any of the boxes that don't look important or look like they don't belong.
If you have any spyware or virus software installed, you should run it from Safe Mode if you can get in.
If you cant figure it out that way you can take a chance and try a repair installation of Windows XP. This will reinstall Windows and leave your programs and files intact. There is a chance of something going wrong so be aware of that if you cannot back up first.
If it is a hardware problem then it could be a few different things. If your power supply is going bad it could cause this.
Then again it can also be something more serious as a motherboard or RAM problem. It is hard to say which hardware component it could be. I suggest taking it somewhere that they can test it if the above software ideas don't fix the problem