This may be really dumb, but that CNTRL+Backspace, does it look like this? C:\ > Do you have a dos floppy in your floppy drive? Maybe a Winders 98 boot disk or something?
Try removing all the media, except the Zip disk if you have one. For some reason, when I used Mandrake 9.2, it absolutely refused to boot if the zip was empty.
Is that a bug or a feature?
Like I said, probably really dumb question. I hope it helps.