iTunes won't play purchased songs - "not enough memory"

[livingfortoday]

Gah! I can't get iTunes to play any of the music I've bought from the iTunes store! Whenever I click on it, it asks me for my password, i enter it in, and then it tells me that "There is not enough memory available". I know others have had this problem, and that reinstalling iTunes has done the trick. For me, though, that doesn't seem to be an option. I've reinstalled twice now! I deleted anything and everything that was even remotely related to iTunes and reinstalled, and still nothing!

Any ideas?