I have an Early 2009 (Mac 4,1) Mac Pro. It has the factory-installed Superdrive as well as an internally installed third party Blu-ray burner. I bought this system used several months ago. It was running 10.8.5. I had used the Superdrive to read successfully, but I hadn't tried burning on it. I had never tried the Blu-ray burner, though (of course) I had the original owner's assurance that it was working (whatever that may be worth). I updated my OS to 10.9 shortly after it went public a few weeks ago. At this time it had been at least a week or two since I had used the Superdrive. A few days after installing 10.9 I had burned a DVD on my PC and carried it to the Mac Pro to transfer some files. Well, the Superdrive spun the DVD a bit and made the usual sounds, then ejected the tray (no error messages). After trying two or three more times with the same results, I decided to try using the Blu-ray burner to read the DVD. Well, I can't read it using the Blu-ray drive either. It behaves just like the Superdrive, except the drive tray didn't auto-eject. Once it's loaded, there's no indication that the disc is visible in Finder or Disk Utility. I disconnected the Blu-ray SATA cable to test with just the Superdrive. Nothing changed. Next, with just the Superdrive still connected, I tried to get the system to boot from its original distribution medium (Leopard 10.5.x). But the tray simply ejects after the disc spins for a moment. I connected a SATA hard drive to each of the internal optical device SATA connectors. It works just fine on either connector. I've tried resetting the SMC and the NVRAM, with no improvement. It seems most likely that the Superdrive is failing. I'm just hesitant to run out and buy another before exhausting all the other troubleshooting possibilities. I find myself wondering if Mavericks could have somehow changed a hardware setting that 1) broke the media-sense function on both drives and 2) doesn't get reset with either SMC or NVRAM. This seems like a long shot. Other ideas for things I might try, before I spring for a Superdrive replacement?