Question : Finding correct problem on PC

Hello!

I have an interesting problem with Windows XP PRO. Sometimes the computer just shut`s down. For example I did a defrag and after 1 hour it completed sucesfully. Then I did a SP3 upgrade and it shut down.
- I scaned for viruses
- I scaned for computer errors
- I checked for overheating problems
- There is nothing in event logs

Can you suggest me some kind of a program for diagnostic which would log all the problems so I could see what causes the shut down.

Thanks!

Answer : Finding correct problem on PC

The problem was in power supply :)