When I'm burning either a data DVD or a video DVD every once in a while the DVD fails verification. The burn goes ok, then on the last step of the process (using native Mac functionality to burn) it will get 10% to 15% through verification then give an error saying verification failed. The disc will usually work (I can see the data or watch the video) so I've ignored it. Could my drive be bad already (brand new iMac) or is this normal? I'm using Memorex media.