That's because you can't have Shake and Doom3 installed on the same machine...
No, seriously, the culprit is that little ATI icon showing on the lower right... If you really bought Shake when it was available for Windows, you should know it didn't deal ok with ATI cards, don't you?
And if you really own it, as someone suggested before, it shouldn't be so expensive to buy a Mac and update it to version 4.
Just my 2 cents, anyway...