I was getting "medium" disc errors when trying to burn a DVD. Also, the dvd drive will spit out the CD a few times before it starts working. I switched to a different brand of Blank DVD's: No good I try burning the DVD at the slowest speed possible: No Good Then I proceeded to: A mac hardware extensive test: everything passed I did a PRAM reset. and did a repair disk permission. No cigar. The only option I can think of now is to try to clean the superdrive with compressed air. I recently upgraded to Mountain Lion, so I don't know if that could be the cause of it. Specs of computer are in my sig.