Unknown problem: Computer hang

Hi there,i have a problem with my computer. It suddenly hang after around half an hour - even though i don't open a lot of programs. I can still move the mouse but taskbar and programs don't react. It also fails to open Windows Taskbar Manager (alt+ctr+del) so i have to force the shutdown everytime it happens. I scanned my pc with Adaware and Avira, but the windows hang halfway through.I've removed all the software that i don't need but the problem still occur.
So i don't know what else to do , hope i can get help here ..

Hello,

Please read this topic:
http://www.geekpolice.net/-t3821.htm

And post a HijackThis log here for inspection.

http://www.geekpolice.net/virus-spyware-malware-removal-f11/