pc switching off

hi, my sons pc keeps switching itself off. when he switches on it boots for about 2 1/2 mins then just switches off. can anyone help me pleeeeease he is driving me mad.
he is lost without his pc
thanks

Please describe in much more detail. Does XP load? If so what is being opened or run?

Does it just power off? Any error message? Is it always the same? Was it OK previously?

Will it run in Safe Mode?

Try booting into Safe Mode options:

After the power-on and BIOS POST or your Logo screen repeatedly tap the F8 key or hold the Ctrl key before Windows starts.

had this error when I switched on today????

Error caused by a device driver
Thank you for sending an error report to Microsoft.
Error report summary
Error type : Windows stop error (A message appears on a blue screen with error code information)
Solution available? : No (see Next steps)
What does this error mean? : Windows has encountered an error from which it cannot recover and needs to restart
Cause : Unknown device driver
Computer symptoms : A message appears on a blue screen with error code information (for example: e.g. 0x0000001E, KMODE_EXCEPTION_NOT_HANDLED)
Additional steps for you to take : Important: Please continue to send error reports so analysts at Microsoft can study and try to correct the problem as quickly as possible
Information about this error
You received this message because a device driver installed on your computer caused the Windows operating system to stop unexpectedly. This type of error is referred to as a "stop error." A stop error requires you to restart your computer.
Next steps
We have analyzed your error report and at this time are unable to determine the exact cause of the error. However, Microsoft will continue to analyze this error report to try to determine the specific cause of the error. If we are able to find the cause and correct it, and you encounter the same problem, you will receive an updated response that includes instructions for resolving the problem.

Is this a new problem? Any new hardware or software?

Can you start in Safe Mode with Networking?

If so do the following:

Go to start | search (type in) .dmp
Note the location of your .dmp files.
Remember this location and the path that leads to it.

Then:

1) Download and install the
Debugging Tools from Microsoft

All you need do is download and install this. Make no attempt to start or run it.

2) Download and install this
debugwiz

This is a DOS based batch file that will command the above Microsoft Tools.

3) Open the Wiz & Browse to, or paste in the path to, your .dmp file.

4) After the Wiz creates a Text document attach it back to this thread.