I've got a MacBook Pro Retina running OSX 10.8.3. The disc drive I am using is a portable external blu-ray drive - Pioneer BD-RW BDR-XD04. I could play discs from it, but I couldn't write to it. It also wouldn't be fully recognised in Parallels (running Win XP) (Parallels would say "Unable to connect CD/DVD 1". Explorer could see the contents of the discs but couldn't boot from it nor could I run some installers from those discs - I had to copy the contents on the local hard-drive first). BUT I found a solution. Hope this may be helpful to others and so am posting it here! Not sure if applies to other external drives too, but it may. Problem seemed to be that the drive wasn't 'fully' 'accepted' by the Mac OS. I checked: Apple icon (very top left of screen) -> About This Mac -> More Info... -> System Report and looked under Hardware -> Disc Burning and saw the that although the device was connected and visible in Finder, it WASN'T listed here. The reason seems to be because I WAS CONNECTING IT VIA A (POWERED) USB HUB. I connected the device directly to the Mac (using BOTH the supplied USB plugs, both plugged directly into the mac via the two USB ports) and it now appeared in that System Report. This then resolved the problem that the Mac couldn't recognise blank media in the drive and meant I could now burn using that DVD/blu-ray drive. (AND re Parallels... I could now choose Connect in the Parallels Configure -> CD/DVD menu and it actually would! May have had to reboot Parallels first, can't remember. Now my software could see it properly - ArcSoft TotalMedia Extreme, which is unusably terrible for playing DVDs/Blu-rays BTW. Before it could only see the drive as a "VIRTUAL DVD-ROM" and refused to recognise any media - blank or otherwise - but it would now fully recognise it.) Curiously, since attaching it directly I CAN (at the moment anyway) now connect via the powered USB hub. I think perhaps it just needed that initial direct contact, not sure.