Believe it or not, it is crashing, just not with the normal "warning bells".  You may have an object or mesh that's incompatible with your game.  What you might have to do is start taking those custom content files out of your Downloads folder, move them to a safe place, and test small groups at a time by starting up your game until the problem reoccurs.  It's a painful process, believe me, but it helps in finding the problem file(s).  :angel:

Are you sure you downloaded stuff compatible with your games?

If you did, then try deleting your groups.cache just inside your Sims 2 folder. The game makes a new one when you start it up.