The password. Every time I go back into it after a respring, it asks me to enter a password, and then re-enter it to confirm, and then asks if I want to use the default or create a custom greeting.
Doesn't happen to me on 4.0 but it did on 3.1.2 right after a JB. Let me dig up some links to see if they can help now.
Edit: Couldn't find exactly what I was looking for but it was on 3.0 and had to do with updated carrier files for tethering. The fix for it back then was just to change your VVM pin. You should be able to do this from the website or over the phone via automated settings.