I've been having a similar issue. Except that my iTunes wasn't playing anything. it just froze and the only way to get out of it was a force quit. And now it won't restart. It just locks up with a beach ball. which is super awesome cause I can't sync my iphone or my ipad and haven't been able to for two days while I try trashing the prefs, trashing the library file and so on trying to get it to work again