[Wlug] Booting Mepis from USB cd rom

Just acquired a new laptop that doesn't have an internal cd rom drive, just a "d-bay" usb cd drive. I had been using Mepis on my previous laptop, and I enjoyed it. But the Mepis Live CD chokes when I try to boot from it. The cd does boot in other pcs, so the media is good. I checked my bios boot settings, but I can boot Knoppix and Ubuntu live cds. I figure that to get other Mepis booted there must be a cheat code I can pass, but my little bit of googling didn't help. Couldn't find anything on the Mepis forums either. Could anyone explain what's going on, or point me somewhere for more knowledge on it. I'd like to understand more how a live cd boots and what the difference between a usb cd and an internal cd rom drive are.