Library file cannot be saved. You do not have enough access priviledges

When I'm using iTunes, I keep getting the message, "Library file cannot be saved. You do not have enough access priviledges for this operation." One suggestion on a forum was to edit your priviledges, but there was no edit tab when I clicked properties. Also, the iTunes DJ stopped working months ago, and nothing I've tried fixed it. It won't burn CD's either. I'm wondering if I have too much music and the program is overloaded? We have 13,125 songs plus many podcasts. Why is iTunes totally shutting down on me? I tried reinstalling, but it didn't fix anything. Or maybe I didn't reinstall correctly?