Booting from a Smart Boot Manager floppy, I've been able to work around Boot Error failures with the latest CD Shell, as used on Ultimate Boot CD 3.3. This might apply to people experiencing 808xxxxx (or other) errors, described in other threads on this forum.
It's quick and painless to download what's needed to create a Smart Boot Manager floppy:
My boot failure is due to an old BIOS, which -can- boot from MS-DOS-bootable CDs, because those CDs emulate a floppy disk. My BIOS fails to boot from from ISOLINUX (syslinux) or from CD Shell, as both of these boot loaders lack floppy-emulation mode.