Developed Graphics Glitch...

[Black Waltz]

Strange. I installed Civ IV a few weeks ago when I got a new PC. (AMD Athlon 64 3500, 1GB ram, Nvidia 6600GT 256MB). At first it ran fine except for a slight sound distortion, but now I am getting quite jerky movements when zooming around the map before you get to globe mode. With just two cities. It used to be fairly smooth but now it seems to be jerky as hell and quite annoying. The problems seemed to happen after I tried to play Morrowind, I updated my graphics drivers and such. But I have tried rolling the drivers back, uninstalling the game. I have even system restored with no improvment.

Does anyone have any idea what is wrong? Or have I just buggered it up in some unknown way?