8.0 RC1 cd boot problem

[grarpamp]

I did make release NOPORTS, NODOC, of and on the same RELENG_8,
and burnt the now nicely CD sized dvd1 image onto a CDR.
 515411968 bytes RELENG_8_20090928-i386-dvd1.iso
Using both the dvd and cd drives, the MD5 and SHA256 match.
I can mount the iso and all is fine. Booting it looks normal up until I see:

Bios drive C: is disk1
_

where the underscore just sits there blinking.
At that point ctrl-alt-del is the only thing left to do.
It does this on both secondary master and secondary slave drives.
Anyone else seeing this?