Can't play campaign

[MrUncool]

Okay, so I got the game Sunday night and installed it, whoop-do-do, everything ran perfectly fine. However, today, i booted her up and tried to get into Outskirts... I see the little "Halo 2" loading image kind of greyed out, and it flashes like crazy while I hear the sounds of the level going on. SO...I did a reinstall (shit, this took fucking forever, I only got it to reinstall using Tray and Play...don't ask), and it still didn't work. Multiplayer still works fine. Oh, and the menu lags a lot until I alt-tab and alt-tab back into the game...this also started happening today.

Edit: Forgot to mention campaign worked fine too, played all of cairo and most of Outskirts, stopped to go to sleep.

Specs:

Intel C2D E6400
OCZ Platinum Revision 2 2Gb DDR2-800
2x8800GTS 640 in SLI Drivers: tried both 158.18 and 158.43

Any help would be appreciated, thanks.

[Melterx12]

Try forcing Vsync off in the NvidiaControlPanel 3d settings.

[MrUncool]

Damn, still doesn't work...the funny thing is it worked perfectly fine the other day. Don't know what's wrong now.

EDIT: Setting AA/AF to "Application-Controlled" seemed to fix it, does anybody know why? It was on 16x/16xQ before

[Melterx12]

Oh, of course, turning AA up higher than the application is compatible with (in this case, 4x) will cause problems in many games. YOu can force AF up without problems, just keep AA at App control.

[MrUncool]

It USED to work :P. Oh well.