MBR not suitable as boot device; installing to partition

[Oliver Hookins <ohookins gmail com>]

I'm setting up a kickstart installation environment for RHEL-ES-4, and
created a kickstart file using the kickstart configuration generator.
When I boot the new machine from the network using the kickstart file
it generates the message:

* MBR not suitable as boot device; installing to partition

And proceeds through the rest of the installation. After rebooting,
the machine hangs at the GRUB prompt. Something is not right here, the
commands used in the kickstart file with regard to the disks and
bootloader are as follows:

bootloader --location=mbr
zerombr yes
clearpart --all --initlabel

It is installing to SCSI disks in a RAID1 configuration but that
shouldn't make any difference to how GRUB is installed - it hasn't
even reached any partitioning information at this stage. Any ideas?
This definitely wasn't an issue under RHEL-ES-3.

Regards,
Oliver Hookins