I'm feeling somewhat nice here since I have the same setup. And while I should just tell you to go to coconnor's thread and fend for yourself since in reality that's all you need to do, I'll provide an updated OMG WITH PICTURES version for us. Which is not nearly as pretty as the original but meh.
Open the package contents of The Sims 3. (Find the app => right click => show package contents.)
Now go to your Documents/The Sims 3 Folder. Delete all four cache files. If this doesn't work, drag the whole damn folder to the desktop and make the game rebuild it. You can put saves, installed worlds, screenshots, downloads, and custom music back in there.