Some Local Files glitches

[-TaylorGang-]

Some of the mixtapes I have in my playlist seem to not be working, One time it will, but sometimes it wont. The track will play slow and fast and the beat and things will be off. I tried taking them off and then putting them back in. At first it works, but then it goes back to what it was doing. Need Help! I didn't have this problem on my iPod, but I recently got a Driod and been having problems.