Itunes will not let me log in on my Mac. The pop up keeps coming and not allowing me access. I even reset my password. I haven't been able to shut my computer down since because Itunes wont allow it.

An Itunes notification keeps popping up on my mac asking me to log in. It will not actually log in when I submit my ID and password. It disappears for a second then pops right back up. I have done a password reset and it still did the same thing. I can't shut down or restart my mac because of this pop up won't close and wont allow me to log in. The Itunes icon is always bouncing in my icon bar. It drives me crazy! Please help!!