What do you mean SimPE is crashing. What error messages are you getting. And is your game running while you are trying to open SimPE? If so that's the problem.
Oh, and what do you mean NPC's are "overtaking" the 'hood. NPC's are only generated at need. If one dies, or becomes part of your household, a new one will take its place. They don't "take over" unless there are bugs involved.
You will have to be a little more qualified in describing your problem, if you want useful help.
As they say in the computing world. Garbage in, Garbage out