"A serious error has occurred..."

I reinstalled The Sims 3 yesterday, and whenever I try to load a save or begin a new save, it immediately crashes, and I get this message:

I even made a new folder, but it still does it. Could it be my CC or mods? They were fine the last time I played months ago. (Aside from half of my CC getting disabled by CC Magic, but that's a different issue.) It won't even open a save/town for me.