Sorry for the late reply. That error is an access violation, and unfortunately, it could in theory come from a number of places. But the first suspect would still be something in your user data folder that the launcher can't handle. Can you install content into a clean Sims 3 folder? Even if you'd like to keep the content from the old one, this is a good test. And while it's more complicated to install in a clean folder and then move the new files to the old folder, it can be done.
And just to clarify, can you play a little bit, but the game crashes frequently; or can you not even play at all? Is this true for a new save or just your existing ones?
