I have TeraByte BootIt only problem I found was that if I tried to boot the cd through
BootIt (I.E. next boot device or CD option) then Knoppix would start to
load then fail. but once I went to bios and changed boot order to CD first I didn't have a problem.

I guess if your sure your CD drive is bootable (loads a windows CD or the like)
then maybe try unpluging the HDDs that way they couldn't boot for sure.