Force shut down necessary after using iTunes
I have an Intel Core 2 Duo Macbook Pro running Mac OS X Lion. Unfortunately if I've used iTunes at all my laptop will only shut down if I hold the power button for 10 seconds. This occurs after every application including iTunes has been shut down. If I have not opened iTunes during a session then the computers shuts down normally. Can I do anything about this, is it serious, and has anyone else encountered the same problem? Thanks for any help givien.
PowerBook, Mac OS X (10.7)