Hi, welcome to forum.
Maybe it's just a drivers issue. Update mobo's chipset latest drivers here
' ">http://nvidia.com/content/drivers/drivers.asp and Gfx drivers here
If the drives update don't solve the problem, disable the "AGP Fast Write capability" in BIOS, set the "AGP Aperture size" to 64MB and "AGP frequency" to 66Mhz.