Introversion

I've searched several forums for help on this but have yet to find a solution. I originally tried the demo about a year ago and it worked perfectly fine on the computer I'm currently using. A couple days ago, I decided to finally buy the full game and when the main menu came up, the lag with the mouse was unbearable. As soon as I attempted to start a singleplayer game the whole thing stayed at an unplayable 4 FPS throughout. I tried turning the settings down as far as I could, but it doesn't help at all. Any sort of help on this would be appreciated.

Here are my computer specs.-

Windows 7 32

Radeon X1950

Intel Core Duo 2.66 GHz

4 GBs of RAM