Hm, not enough for me to tell what the problem is. I've yet to have any such problems without altering Pitch.
Are you making sure to wait long enough between the Load and the Play? If you're doing a puzzle that requires multiple tracks, I'd make sure they're all Loaded well before you need them. Probably when you start the puzzle.
(Another possibility did occur to me, but shouldn't be the case, especially if you're playing it with "instant".)