If you are a user of Vuze (formerly Azureus even though it’s been long enough to stop saying that) then you may be encountering the same problem that I’ve been encountering. Vuze (on all platforms) crashes or freezes when you add a torrent.
The fix is as follows. Go to: Tools -> Options -> Connection
Under Connection uncheck the box that says “Prompt for selection when a tracker with an anonymous tracker is added”.
DONE. That was easy. Vuze has already acknowledged this problem and issued a patch but this will work for now.