Windows 7 Freezes a Few Minutes after Start Up

Hi, I just upgrades to Winodws 7 64 bit from Vusta 64 bit 2 weeks ago and it has been working fine until the last day or two. Since then, the computer has started to freeze within 2 or 3 minutes after it starts up. I even tested it and it will still freeze on the log in screen. When the system does feeze, sometimes the mouse will move temporarily, but it will usually stop moveing altogether. Also, the keyboard will not work and any sound that was playing at the time of the freeze will loop or just go crazy. The only things I have that run when the system start up is AVG Anti-virus, Precision (my overclocking/ fan speed tool), and Spybot Search and Destroy + Teatime. I can'y think of anything that I downloaded or installed before this happened and I think it just started out of the blue. I never had this problem with Vista, so I don't think it is a hardware problem, but I can't do anything while my computer is like this. Does anyone have/had similar problems or know how to fix mine?

My specs are:
AMD Phenom II X4 955(3.2GHz) 64 bit Quad-Core Processor
8GB DDR3 1333 RAM
1TB SATAII Hard Drive
NVIDIA GeForce GTX-275 896MB
Integrated Sound card
Power Supply 700W
Windows 7 Home Premium 64-bit

What does event viewer say ?