If parts of your neighborhood files are write-protected, perhaps because you have a dead SimPE hogging things, or a halfway-dead TS2, or simply don't have write-permission to the files, your neighborhood will be buggered whenever TS2 tries to save anything to it.

Hm... the only answer I have is not at all a good one. If you go to the "Firing Range" forum here, click on the "No secret society respawn" thread, and then scroll down to sandilou's post you can read why this might be happening to you. She puts it much better than I could, I have a tendency to get entangled in my own sentences when I try to explain something that is not entirely clear to me either.

JM has some critical fixes available that deal with the "too many sims" maxis bug. It might be a good idea to install those for any future implosion preventions.

G.

I've found that the only way that works tends to be the cake and even that isn't always successful.  Sometimes the cakes become unusable and I have to buy another one.