Open the computer case. Search for all the little fans. Is each one turning
at a good clip when you turn on the PC? Remove all the built up dust,
especially from the CPU cooler. It sounds like you have an overheating
condition.

Signature
Regards,
Richard Urban
Microsoft MVP Windows Shell/User
Quote from George Ankner:
If you knew as much as you think you know,
You would realize that you don't know what you thought you knew!
> hi sometimes my system just switches off for no reason, can can anyone
> help
[quoted text clipped - 3 lines]
> wait 30 mins or so i can switch it back on and its fine for another hour
> or so