Make sure you run through this http://isboxer.com/index.php/compone...o-with-isboxer

If you're not on the development build of IS, the game is in Direct3D9 mode, or the turbine download manager is enabled, it will not work correctly. If it is working correctly, when the game window is up you should see an FPS indicator in the upper left corner (for example "FPS: 30"). If you don't see that, it's PROBABLY one of those three things.