Okay, I'll take a stab at it.
1.) What drivers are you using for your 8800?
2.) Have you installed the latest DirectX?
The driver support for the 8 series is appaling. I had to take mine back because I couldn't be assed for driver support. It was causing way too many problems in my games at the time (EQ included). I'll probably get one after some more DX10 games roll out, though - (Call of Juarez and Lost Planet don't count, heh). But waiting a good month for drivers really had me on the edge after dropping an arm and a leg for that card. I could have built another server box, lol.
You might have a better chance looking at the tech support forums on the official site. They usually have a plethora of answers there. Most of the answers that are listed are from the official site - just copy/pasted here for sanity's sake.
Speaking of sanity, I'll link the troubleshooting list from the official boards so people can find it here. This doesn't pertain to you mainly, but about 90% of the problems I see posted here are already covered in
this topic.
Threaded Mode
