7950gx2 no longer working with multi-gpu

Asus M2N32-SLI Deluxe
Single 7950gx2
Antec 550W PS
Win XP PRO x64

Been working on this problem for weeks and I'm at a loss. Been using same setup for over a year with the vid card running in multi-GPU mode with no problems whatsoever.

All of a sudden, with no changes, windows fails to load after the intial windows load screen.

Have tried a dozen different drivers and depending on the driver version, either I get no signal from the monitor, blank screen, BSOD, or a constant reboot cycle. Tried a different monitor. Have tried several different Asus MB drivers. Have tried several different MB Bios versions. Have reinstalled Windows several times. Unplugged everything from PS leaving single HDD and vid card. There is no jumper on the board to enable SLI mode. There is no option in the BIOS to enable sli mode.

Windows regonizes both GPUs on the vid card as it does install two drivers for the two GPUs on the card. But the ONLY way I can get windows to load is to boot up in safe mode and disable one of the drivers.

Have already RMAed vga card and was returned with same problems. Since it happened with no changes, makes me believe it's a hardware problem. But everything loads fine in safe mode, which leads me to believe it's a software or driver problem.

Any suggestions appreciated.