Gaming Computer Randomly Freezes

Hey Guys, I just built a new gaming computer with the following specs:

GIGABYTE GA-EP45-UD3R Motherboard
Intel Core 2 Duo E7400 Wolfdale 2.8GHz
EVGA GeForce GTX 260 Core 216 896MB
Seagate Barracuda 7200.12 ST3500418AS 500GB 7200 RPM
G.SKILL 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 1066 (PC2 8500)
OCZ StealthXStream OCZ700SXS 700W
Pioneer 20X CD/DVD Burner

I have Windows Vista Business (64-bit) installed, Firefox, and a few games. The system plays the games flawlessly and has never crashed or froze during a game. At random times when I am just messing around in Visual Studio or browsing the web the computer will completely freeze. I have checked the error logs in Vista's administration tools but didn't find anything. I ran Vista's memory diagnostics and everything came out clean. I also ran a seagate program to check for problems with the hard drive but found nothing. The system seems to be staying cool, the processor never reaches above ~38C when just browsing the web and never reaches above ~55C when playing games. I have updated to the latest drivers on my video card and processor but it still froze. Your help is very much appreciated. I really hope it's not a hardware issue