OK I'VE FIGURED OUT WHAT'S THE PROBLEM
when I install service pack 2 on my windows xp pro, Windows Live Messenger starts to act very weird. It starts 'windows installer' and starts correcting live messenger. In that process my computer shuts down (crash, obviously).
now that I uninstalled sp2, it acts like nothing happened
anyone a sollution to this?
btw thanks for the comments so far