Re-Installing from CE Disc?

[SEE]

The game has gone into slow motion and the sound has become a mess - Engines are a awful drone, character voices are slow,distorted and jumbled in with the monotonic sound of what is supposed to be the engine. There is a two second lag from my Stick inputs and it takes about 20 seconds for the game to render at the start of a mission.

I don't think its a hardware problem as IL946 maxed out using missions on Cannons Map play perfectly well and uses 1.6Gb of Vram.