What the hell is up with that? The software setup for the ripper I'm using is exactly the same on both the Macintosh and the Xubuntu box. Is this some Mac OS X thing, perhaps? If so, that's not cool at all.
It probably has something to do with the kind of dvd drive that's in there... I'm not sure, but I believe there's a 'security' feature on a lot of discs that prevent them from being ripped in a lot of drives.
Then again, I may be wrong.