Why won't iTunes work on my iPod touch?

I tried to google it and found nothing helpful... When I go Into the iTunes app, it won't let me preview any songs, it goes super slow, and I've had to wait over night for it to download one song a few times... I have the 4th generation iPod touch (with the camera) and it's not jailbroken or anything... What's the problem and how do I fix it? :/