Please tell me the entire hardware configuration for your system. You'll need to do a process of elimination, however. Run Memtest86 on that computer first. You may have a bad stick of memory. Have you overclocked any components? Can't help ya until we know what you are running in that puter. If the memory is good then you'll need to boot that puter with only the hd, video and memory. If it freezes with a minimal hardare set up then you're down to the hd,video, psu and mobo at least. If all is well with the minmal boot start adding stuff till it freezes. capice?
Noli Nothis Permittere Te Terere!!
EVGA 680i, Dual EVGA 8800GT'S (650/950), 4 gigs OCZ DDR2 1066, Intel Q9450 at 3.8 Ghz, Koolance Water Cooled, Dual Plextor16x DL DVD+/-RW. Dual WD 250gb 16mb Cache Sata 3.0. 3DMark06 score = 19,168.