Blue screen would appear and error message would prompt on the computer, or after the message prompts, the computer would auto shot down. This is a malfunction many people meet. Mostly this problem is caused by software, of course it’s quite likely the problem from hardware—bad quality hardware. Sometimes, thing’s much more complicated, probably after the problem occurs, software fails. So you’d first to make sure there’s no problem with the hardware, and then check up software. Basically this is the method.
A-1: Setting for this session is to ensure that there’s no any problem with the power supply system. To ensure voltage stability and enough power to supply the entire computer system, first of all, no matter whether your power supply is now or old, you should change a new one for temporary maintenance. As a good power supply system is much enough to let you avoid many incorrect judgments because of power supply problems, and the computer repair process would be much easier and faster.
Please notice when replace power supply, to ensure there’s no man-made failures when changing power supply, please after changing the power supply, pull out all wires and then plug them back again, including IDE cable, ram slots connection, video card. Make sure there’s no bad connected cable or card.
Now you could start the machine, if the failure disappears after starting, no blue screen, then the failure is probably on the power supply quality or the cable connection. Now you could plug the old power supply back and restart the computer. If failure happens, then it indicates there’s something wrong with the old power supply quality. If no failure, then it’s the cable connection problem. Congratulation, you’ve fixed up your computer now!

A-2: this Step is set to ensure when system failure happens, then to judge simply whether the problem comes from hardware or software. Simplify the judgment process.
Now there’s a problem needing confirmation: the problem happens before Windows loading or during Windows loading. If you cannot ensure of that, then pull out IDE cable, meaning to pull out the cable connected to hard drive, and then restart the computer. If there’s no problem happening to the machine, namely, no Blue Screen, no Error Message, then the computer would not shut down, so the problem is happening during Windows loading. Then failure range is 95%, which is a software problem. So if the failure still exists after pulling out cable, the failure range is 95%, then it’s a hardware problem. If you are sure that the problem is happening before Windows loading, then go to the Step C-1.
If you are sure that the problem is happening after Windows loading, then go to the Step A-3.