Hey, I have the same issue with the Mbox Mini on a 2008 MBP. To be honest, I'm not very happy with the solution of restarting every time I need to unplug my mbox.
What's the point of having a portable computer if you can't take it anywhere without shutting it down all the time? As I'm always moving around, I sometimes don't have time to shut down, and so if the mbox is still plugged in, it means I'm going to have a kernel panic while I'm out somewhere! Is there any word on new drivers or a fix for this, because the workaround is not acceptable!