Playback Frozen in iTunes

Question

OK, here's the deal. This question is directly about one major problem I'm having, but it's also about something else, just cause I'm going to mention it here, rather than in another post.
Problem number one: When I double click on a song (or on an album in CoverFlow), nothing happens. It says it's playing--there's that little blue speaker icon next to the song, except the little song progress bar just sits there. There's no error message or anything. It just does absolutely NOTHING.
I recently recreated my iTunes Library, because of another problem I was having, which was the error "The iTunes Library could not be saved. An unknown error occured (-49)" So, after I did this, I didn't get that error aghain, AND my music worked fine, for a couple days at least. And, then, all of a sudden, for no reason I can think of, the music WON'T play! (Oh, and that error popped up again at the same time, but it hasn't happened again for some reason)
So, I restarted after I discovered this problem. No luck. I repaired then uninstalled and reinstalled QuickTime (as in http://discussions.apple.com/thread.jspa?messageID=6723813&#6723813). No luck. I have absolutely no idea what is wrong. My music is still there, I checked in My Music.
Any help would be GREATLY APPRECIATED!

Answer 1

1) If the diamond won't move
Check the compatability settings for QuickTime and iTunes:
http://docs.info.apple.com/article.html?artnum=305212
2) Sounds like your library ITL file got corrupted.
http://docs.info.apple.com/article.html?artnum=93732
This could be due to any number of reasons:
- Windows OS permissions
- security software
- malware
I make regular backups of that file at least weekly, more often if I've added lots of music.