when pandora acts like that (can't choose a channel), i usually quit it and open it again, seems to fix it, for a little while at least. not sure if it's a network issue.
pandora hasn't FC'd on me yet (knocking) and the headphone/phone call "coordination" seems to work better (unplugging headset pauses music, etc.). something weird that seems to happen is after i plug in a headset, pandora pauses, but only eventually. i don't think it's instant, usually it's like 30s or something.