HOw many memory sticks installed? If you have two, switch them out and see If you have a bad memory stick. Ohterwise, pull all PCI cards and try to boot. Insert each one in progression. If it is a pci card failure, it won't take you long to find out which one is the culprit. If not hardware...reinstall windows after saving data.
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.