Hardware Interrupt help

Hi all,

I've built a new system:
Shuttle XPC SN68SG2 Barebones Mini PC AM2 GF7025 DDR2 PCI-E16 1PCI SATA Video Sound GBLAN 1394 250W
AMD Athlon 64 X2 3800+ EE Dual Core Processor AM2 Windsor 2.0GHZ 512KBX2 65W 90NM Retail Box
Corsair XMS2 TWIN2X2048-5400C4 2GB 2X1GB PC2-5400 DDR2-667 CL 4-4-4-12 240PIN Dual Channel Memory
Western Digital SE16 320GB SATA2 7200RPM 16MB 8.9MS Hard Drive OEM 3 Year MFR Warranty
XFX GeForce 8600GT 540MHZ 256MB 128BIT 1.4GHZ DDR3 PCI-E Dual DVI-I HDTV Out DIRECTX10 Video Card

The system works fine provided I don't have the video card plugged in. When I plug in the 8600GT, the system locks up, and cannot even start windows. There was one time where (it only happened once) it got into windows, I opened up process explorer to find that the hardware interrupt is 100%. Can anyone tell me what the problem is? It almost seems like there is a hardware conflict somewhere. I've tried to load the fail-safe, optimized, and even tweaked with the bios settings. Nothing seems to work.

Fortunately, I am able to get into Windows Safe Mode without a hitch. So I've installed the latest drivers, and have flashed the system bios to the latest version.

Does anyone have any tips as to what I can do to get the system working with the video card?

Thank you.