I really think at some point we ought to give you a tutorial on how to back up your Mac, so that if problems strike...you won't be worried about wiping the lot of your hard drive and loading everything back on.
I wipe my drives at least twice a year and reload everything back on, I find it makes everything run nice and smoothly all the time...
...plus if disaster did ever strike at least all your important documents would be safe.
I am talking as a man who has many , many , many years ago lost important work because a hard drive blew...never again...now chant after me...I must backup...I must backup...repeat 100 times...
Maybe I'll put something in the hints forum...
...if you had to force quit iTunes, always do a restart before trying to relaunch it again... helps it clean up any mess that was made !