I tried 2D mode and it doesn't stutter at all in the tower, but when I launch my plane I can't use the keyboard %) I'm guessing if I got the engine started and flew, it wouldn't stutter. What does that tell us?
Next idea: Decrease your settings from nvidia to "stone age". It might be graph card drives issue. Saw post on the other forum where the fix was to get older drivers for the GC. Also check if you have some proggies running at the same time. Just in case. (What machine you have?)
I downloaded and installed DX9, but no difference It's a "AMD Athlon(tm) 64x2 Dual Core Processor 3600+ (2 CPUs), ~1.9GHz" 2GB RAM. I've been playing AH. And it's good. It's just not the same tho.......
The GC settings are very basic. They were set for "Quality" when I first installed it, then changed to "Performance" a week or so ago to see if it helped. No difference tho. It would help if I could show you the interface, just to show you how basic it is, but I tweaked for a few days with every conceivable setting to see if it would help.......nothing .
I had some AMD/nvidia problems before. There were some conflicts with Athlon processors and DirectX. I had to download special Nvidia versions of DirectX and then I had to go into ActiveX control panel and mess with the settings. There may be new drivers for nvidia more compatible with AMD processors. Now that AMD bought ATI there may a limited interest making driver updates. Have you checked at the AMD and Nvidia websites?