Sims 3 Crashing

...after I start really playing. I can create my sims, buy a house, fiddle with Buy/ Build mode, but as soon As I actually start playing it crashes.

I tried the disabling DEP thing for the Sims 3, BUT I cannot find the Sims 3 files anywhere, and when I copy and paste them from another thread that had this method to fix the game, it says that the file does not exist...

Any help?

PS- I have Ambitions, Generations, and Pets installed as expansions in that order- although I do have Seasons and University Life as well, I just did not install them as of yet. I did have them all installed, then un-instaleld then re-instaleld 2 other times before this due to the same issue.