Yeah, I tried again and I got it out of my game. I guess my game is just being weird tonight. I still get the error after two times of normal saving, but I do think it might just be a union cove thing. I'm going to try and see if it happens in sunset valley too.
I do want to thank you for all your help so far!
You're welcome.
I don't yet have Union Cove, and my laptop probably won't be able to handle it at all, so I'm not sure about that but judging by the problems some are having it might just be.
Trying it with Sunset Valley is a good idea.
EDIT: Perhaps make different Sims 3 folders? I have never done that, but some people suggest that on the Union Cove thread.. Not specifically for Error 12 though, but I wonder if it would better the problem..