This sounds like a driver issue but I don't know: Basically, the problem is that Direct3D based games (Half-Life 2/3DMark05) hang-up on my machine. It renders a few frames but then freezes for about 30 seconds...renders a few more frames...freezes 30 secs and so on. OpenGL (Doom 3), on the other hand, runs just fine. I've upgraded to the latest ForceWare driver (I even tried using the uncertified ForceWare 71.20 from guru3d). I've flashed my BIOS and upgraded my chipset driver all to no avail. Nothing on my system is overclocked...unless it's a factory overclock I don't know about. Is there any way a hardware glitch on my video card would produce Direct3D problems but not affect OpenGL? System specs: EVGA gForce 6800 Ultra Extreme Edition MSI K8N Neo2 (nForce 3 Ultra) Athlon 3500+ 1 gig of OCZ EL DDR PC-3200 Platinum Revision 2 WD 740GD Raptor Turbo-Cool 425 Deluxe Any help/suggestions would be greatly appreciated.