Garry's Mod quiting with no reasons

[KaRay]

Okay, I've tried anything. My garry's mod sometimes freezes, then returns to the desktop without error messages, crashes etc.. The console just says "Disconnect from the user". He's quiting itself with no reasons. I checked the cache, reinstalled garry's mod about 4 times, removed all addons, decrease graphic effects.. anything. Someone got an idea how to fix that? I'm becoming nervous.

Aswell, my system spec:

Intel core2 duo E8400 3.00GHz
ATI Radeon 3800 HD Series
2GB RAM
Windows XP SP2

[Danneh]

Try upgrading to Service pack 3 and check drivers are up to date