The solution is actually in the readme that comes with the game, you just have to be creative. The readme explains that if you have trouble with the HUD in Direct 3D that you have to turn on triple buffering in the options. Fair enough, that works, but not through the game’s own options dialog. You will have to go into your video card driver settings and turn it on there.

If you continue to get problems then uncheck all the shit in your game’s advanced options, if fuckups continue then slowly start disabling other things one by one, like trilinear, AA, AF, Vsync and so forth. Don’t leave them on “application controlled” either, make sure they’re completely off.

I figured this out on a 6800GT – I imagine it will work pretty well with other nVidia cards as well, but I can’t promise anything for ATI users.

Besides this, there is sometimes a problem with the mouse, it will jerk and stick when you use mouselook, but restarting the game usually fixes this, so I didn't look for a solution to that particular issue.