After, I noticed two new issues with Diablo 3.
Firstly, the FPS was stuck on 13-14. Constantly. I was able to fix this by resetting the SMC however.
The second problem though is more of an odd one, I was previously running the game at 1900 x 1200. But now thats no longer listed as an option, instead I am left with odd resolutions like 1898x1186... which look out of proportion.
See Picture: http://i45.tinypic.com/mb3389.png
Any ideas on how to restore all my resolution options?