Hardware driver conflict. Go the the device manager in Safe Mode: anything wiht an exclamation point listed next to the device? He may have a hardware failure such as sound card, or other installed PCI device. IRQL error suggests a bad PCI card or corrupted driver for one of the installed PCI hardware components.
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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.