I have a 15 inch macbook pro, with the MATSHITA DVD-R UJ-868 superdrive in it and my wife does too, I played a new dvd in it yesterday and today it will not recognize it or any other dvd and my wife said the last time she put one in her machine she had a hard time getting it to eject and it would not play or recognize it either. I had mine replaced a year ago, we do not use them much so is the laser lens dirty or what and if so what is the best way to clean it