an exception is thrown in smack 1.4.1, in org.jivesoftware.smack.packet.Presence on line 144 if the priority from a user in your roster is out of the valid range. This causes smack to disconnect. If you get this priority sent to you every time you log on, you basically can’'t log on at all.
I’'ve filed this as SMACK-60.
I just had this same issue, I traced it down to a user in my roster no longer existing on the jabber server. This entry was returning the priority of 9999999.
Actually no - scratch that, wrong jid reference. I notice the user in question is using jacj so maybe the clients being naughty.
The issue has been fixed. You can try it out in the next nightly build.