You could try a factory reset. Copy across any saved items that you want to keep - saved games, library, saved sims, user preferences etc. Copy your downloads folder. (Put them somewhere other than your Electronics Arts folder). Then delete your Sims 3 folder. When you start the game again you will have a fresh folder. You can then paste your saved folders back into the Sims 3 folder, but not the downloads folder. Navigate to your downloads folder, and then reinstall your downloaded content by double clicking each file. You could probably copy over the whole downloads folder and install everything through the launcher, but I'm not sure if you would replicate your problem that way.