I had not used the CD/DVD burner in my MacBookPro very much and was dismayed when error messages signaled a problem.  From the articles and blogs, I gathered some useful remedy might be doing simple solutions before taking the unit in for what I felt was an imminent replacement.  A review by a fellow Amazonian sent me on a search to find the Allsop 23321 before any other.  Cleaning disc in hand I reread the instructions fearful I would mess up on the procedure.  Pushed into the slot I was mildly surprised the Allsop was not rejected.  In a flash the process was telling me I was set to go.  My proof was complete when the next time I asked iTunes to burn a disc -- it happened!  I keep the Allsop in my laptop bag... it's too valuable not to.