The only thing I can think of for why it can't boot from CDROM is that maybe the drive can only handle 650 meg images and it's 700. Just a guess. It seems if you're on enough lists though that the problem appears across the board--I wish I had a solution.
Well, there actually is a solution for blag10k since you can make a floppy. Pop a floppy in the drive, mount up the cd, go to the "images" directory and run:
dd if=bootdisk.img of=/dev/fd0 bs=1440k
FWIW, I've seen it with and without the "bs=1440k" (blocksize).
Then you can boot from floppy and see if it then will then see the CD. If not, net install ;)
(or even more drastically, you can remove the hard drive, install on another box, then pop the drive back in ma's computer).