EA mucked up Belladonna Cove majorly. When they made the neighborhood, they foolishly assigned it the same UID as Pleasantview, which has caused problems in both neighborhoods. When you first load the game, the game will recognize the fact that Belladonna Cove has the same UID as Pleasantview, and so it will automatically resolve the ID conflict. If you've just installed Apartment Life into an existing game, the game will give Belladonna Cove a new UID. If you're regenerating your user files, or if you installed Apartment Life before opening the game for the first time, the game will give Pleasantview a new UID.
Belladonna Cove is broken in itself, even if you removed all your other neighborhoods so BC is the only hood in your game. The pre-made tombstones for the already-deceased Sims in Belladonna Cove are stuck in limbo, and are at risk of being deleted, because EA deleted the cemetery lots they were supposed to be sent to before shipping the game. This can be fixed by making sure Belladonna Cove is the only neighborhood in the
My Documents/EA Games/The Sims 2/Neighborhoods folder, and then using the fixed version of Belladonna Cove and then editing Gamesend Grounds. You can move the tombstones to more appropriate locations as you see fit, just be sure you save the lot before exiting. If you fail to do this, and don't have nounlinkondelete, you risk corrupting your neighborhood.
Probably a more annoying problem (assuming that you care nothing about dead Sims) is the fact that Belladonna Cove is added before Pleasantview when you regenerate your files, so Pleasantview will be viewed as the conflicting crybaby and the game will give Pleasantview a new UID. The problem is, this results in Pleasantview's story being wiped out, so you'll always find Pleasantview with an empty story. Annoying. This can be fixed by giving Belladonna Cove a new UID, either by editing it in SimPE, or by disabling the E001 folder in C:\Program Files\EA Games\The Sims 2 Apartment Life\TSData\Res\UserData\Neighborhoods and then regenerating your files; the game will be unable to find Belladonna Cove, so it simply won't load it, and Pleasantview will no longer have an elephant in the ring to battle with. The problem with the former is that editing the UID will break the tombstones for Belladonna Cove, again resulting in the problem mentioned above. You can use the HoodChecker to fix them. The same problem occurs for the latter, when you re-enable the folder and install Belladonna Cove. Since the game will only pick on new neighborhoods and will not touch the UID for existing neighborhoods, Pleasantview should be home and dry.