I have finally found a solution for people like me, having these randomised freezings. Those are caused by Ethernet controller (to be specific Attansic L1 Gigabit Ethernet 10/100/1000Base-T Controller, that is now called Atheros in Windows 7 and installed by default). The solution is simple (and yet I spent 2 sleeples nights to get it ). Install OLDEST drivers you have, or to put it simple, the ones that came with your mainboard (mine is ASUS P5K). My drivers date from 2007 and they work perfectly. So it seems that older is better. Why am I saying it's a solution? Well, my comp worked 2 days while playing movies and music (constantly), downloading all kinds of stuff and above all I copied over 150 gigs of data from my laptop to my comp whitout crashing or freezing. I think this is good enough to say it's fixed.