I started having problems with my Mac Pro Superdrive. While attempting to burn CD's it would reject the media. It started out rejecting every 4th CD. Then it rejected all media both blank and recorded. I called Apple expecting they would send me a replacement drive. No luck. Instead they had me power off the system disconnect all devices and restart, delete the preference file, restart from the OS X DVD and reset drive permissions and test the system. As impressive as these actions sound, they had no effect. I just wanted a replacement drive. The last straw was a request to reinstall the operating system.
I have spent to much time getting this system set up just like I want it and did not want to face a reinstall. So I purchased two Pioneer DVR-111D drives from newegg.com for a little less then $80 including shipping. Installed both tonight, and problem solved. Have noticed that the new drives significantly outperform the original. Perhaps that because it was faulty ... or the Pioneer is a better performer.
The original drive was a Sony DW-150A. Its one of those you can reportedly hack for better performance. From my experience, don't bother with the hack just replace it with the Pioneer for $32 plus shipping.