I honestly don't know how else you could try to fix this problem, other than editing the .sgr files as @roberta591 has mentioned. (I didn't have to do this, and I wouldn't know where to start, either. At this point, I myself would probably go through the whole process of uninstalling, cleaning the registry with a tool like Piriform's CCleaner (free), and reinstalling from scratch, but editing the .sgr files is certainly worth a shot. You can probably find them here: C:\Program Files (x86)\Origin Games\The Sims 3\Game\Bin but that will depend on where you told Origin to install TS3. Regardless, you're looking for a file within an application's folders, not anything in Documents.
Ok so now I have reinstalled the Sims 3, now the error message I'm getting is pretty much the same but instead, it's Sunset Valley World instead...
