Possible Cause: The workstation that you are trying to boot might have a CD drive that doesn't support multisession CDs. The ZfD imaging CD is a multisession CD because adding the SETTINGS.TXT file (and any other files) to the CD makes it so.
Action: The workstation must have a CD drive that supports multisession CDs. In our testing, we successfully booted an HP vectra VL, a Compaq Prosignia, and a Dell Optiplex, but some other workstations failed, including an IBM PC 300PL, a Dell Dimension XPS T450, and an IBM clone with an Intel motherboard. If you can't use a CD as the imaging boot device, use diskettes.