I mainly use a DSL line and don't have to deal with modems, but right this second I am in Venice, Italy and am dialing up....and have discovered an annoying bug. Occasionally if the modem disconnects accidentally, when you tell the computer to actually disconnect you get a "modem disconnecting" bug that is impossible to stop. You can still work normally, except that you can't connect via modem. This happens even if you log out or switch users.
The only solution is a reboot.
Any idea how to kill this manually so you can reconnect.