get a can of that computer air duster stuff..
shoot 8 - 10 quick shots into the drive to clean it out..
it is possible that it is the disc as they tend to warp in extreme heat or cold (OEM or copy doesn't really matter)
I have OEM AF if you want to buy it from me, or I can offer to make you a backup copy of it and you can try that to see if it clears the problem up..
either way hit me in PM.