After installing JFK FSX there was no buildings to be seen at all. I deinstalled JFK kept addon manager and this coualli or what ever it is called.
If you already had Zurich installed before, you already had the Addon Manager working, so it's not something related to the Addon Manager.
It might be something else that *makes* the Addon Manager crashing. If that one is crashing, is normal you don't see any buildings.
During beta testing, we found another tester that had a similar issue, and it was casued by a scenery.cfg file that was corrupted, probably because of something *else* he installed, that corrupts the scenery.cfg. The Addon Manager reads the scenery.cfg at start, and it might crash if something is wrong with that file.
Can you email me your scenery.cfg, so I can have a look at it ?