I believe that tinging sound is a Jew's harp.
Otherwise, check your CDs for scratches.
Yeah, you're right about Cotton Fields. I checked my 50 Big Ones version and it has the same thing. Weird I never noticed it before. If my CDs had scratches, wouldn't I be having the same problem when playing them in my iTunes library? They play fine there. It's only once I put them on my ipod that the problem occurs.