XP restarts three times once a day

[bbking66]

Hello all,

I've experienced a problem that I hadn't seen never before on any XP machines.

I had a computer where windows 2000 was installed, after a disk format (quick format within Windows XP installation) I installed a fresh XP. It has the SP 3, including all updates, checked with some antivirus, now AVG is on it.

Applications like office/browsers/games work all like a charm. From some time ago, the next situation happens every day now once:
The XP logo is on when the OS is loading. When it's "loaded" and the logo goes off, after the black screen the logon screen should appear. Well, firstly it just restarts the pc. Next time it shows that windows wasn't shut down properly etc.. with all those options to login in safe mode etc.. Now when I chooose normal mode, now after the black screen the login screen comes, voila, finally. Now, when I choose any of two profiles that are created, the system just restarts itself again, and XP shows the not proper shutdown again. This happens again third time, after that everything works well.
Now, after those restarts, when I just turn the pc off and turn back on, it loads and starts properly without any restarts.

This happens EVERY DAY once, after that how many times I restart myself the XP, or just turn the pc off then on, I'm not able to reproduce the problem but the other day again...

Please, if you have any idea what it may cause, let me know. I saved a hijackthis log, even checked the ntbootlog, but I'm not able to identify the problem. In the event viewer there's no signs of errors/special lines that would indicate something goes wrong..

I also have to mention that I already tried to reinstall every piece of driver, with complete uninstall/clear. And this problem never happened with windows 2000, in xp also it didnt happen when it was freshly installed, it just did from some time ago.

The pc was bought as a whole piece. It's a standard Celeron 2.6 GHz, with 512 MB RAM, Asrock P4VM800 MB, AMD X1050 graphic card with 128 MB, PS/2 keyborad and mouse, a USB printer and USB webcam is connected (already tried with these when not connected, didn't help).

I must also tell you, when after first restart I choose safe mode, it never restarts again that day but the other again..