I'm running a Sony Vaio VGC-RA710G with a 3.2GHz processor, 512MB RAM, 250 gig HD running Windows XP Media Center 2005. Every time I have several programs running...like maybe Media Center TV, downloading a movie, surfing the web, etc, my PC will randomly freeze up. No errors, just frozen. The CPU useage rarely goes above 50%...I'm not quite sure what the deal is. I do virus/spyware scans will several scanners weekly, Defrags frequently, etc. Do I need more RAM?

Awhile ago my friend partiotioned my HD so that I have all of my system files on one side and all of my personal files on another. Could this be the problem?