Updates *since* you've been having this problem would not be significant – I meant updates (or other changes) *before* the problem started.
The Riverview thing sounds like you didn't completely uninstall – did you perhaps just remove and reinstall the game itself, leaving your user files where they were?
To completely uninstall the game:
- delete your /Applications/The Sims 3 folder
- delete your /Users/<User>/Library/Preferences/The Sims 3 Preferences folder
- rename your /Users/<User>/Documents/Electronic Arts/The Sims 3 folder – you can keep this as a backup, so that you can put your old savegames, syles, screenshots etc back once reinstallation was successful.