I have never been able to successfully burn a DL disc with my MacBook Pro (13-inch, Mid 2009). I have no problem with single layer discs. I have unsuccessfully tried to find out why and a solution. I've come across mainly stories from others with the same problem and only guesses as to how to fix it. Has anyone succeeded in regularly burning DL discs using the internal DVD drive of a MBP Pro? If so, include the brand and type of the DL disc used, software and burn speed used, and what model MBP used. Thanks in advance.