The boolprop thing... yeah. That isn't causing the errors. Boolprop testingcheatsenabled true is a debug mode used by the designers; it's set up to generate error messages for every little hiccup your game has. If your getting errors with it on, you were certainly getting the same ones with it off, only without the message. A lot of sheeple don't understand this, which is why they blame it for a lot of problems.
I thought so, just checking.
That's what I guessed - just checking. You could probably install Uni without reinstalling any of the other packs, just to answer that question. This means you wouldn't lose your sims.
Don't you have to install them in order?
Edit: Also, Uni discs are AWOL. Is it likely/possible that it could be the absence of Uni that is causing this problem?