I was having trouble running the game, it just wouldn't start at all so I decided to try changing my catalyst A.I settings. I switched it from advanced to standard and now the game runs perfectly on my computer :)
I decided to share it with you since I haven't found this information anywhere and I think this might help other people who are having trouble running this game too.
You should probably have a look at your driver installation then. Having gone through Crossfire with 4800 series cards and a single 6900 series the Catalyst AI has always been enabled and set to Advanced/High Quality and there has never been this issue. This is through 5 or so Catalyst revisions.