I don't know if I have a similar problem but occasionally the game slows down to a crawl with the mouse very erratic and moving very slowly.

When I finally manage to get to the main menu and select Quit the game goes to desktop and again extreme slowness and blank rectangles on screen. The mouse pointer sticks and nothing moves. The only solution I have is to physically press the 'off' button and logoff that way.

It doesn't happen every session but is very annoying.

If this is an entirely different problsm than that above I apologise for highjacking the thread.