Okay, that's good and was important to get out of the way/rule it out.
In that case, since the game performs properly on a new game folder, I would say we are back to suspecting that some form of rogue CC is acting up. Identifying which exactly it might be can be very tricky, it could be one or more sims3packs or something that is coming along for the ride on installed custom lots or sims if you use those. You would probably want to proceed with the new game folder, perhaps adding a very small amount of your CC in at a time while checking to make sure the issue does not return. With enough of that you should hopefully be able to continue with your ongoing saved games copied over if that was part of the goal, only without the crash issue recurring.
