can't find root filesystem on live CD problem

[Ed Berger]

I have a 'debranded' HP m8000n media PC currently with an IDE DVD-RW 
drive, which replaced the original (defective) SATA dvd-rw drive, that 
I'd like to run dragonfly on, but I can't boot up from a dragonfly live 
CD-ROM enough to install.  I have had no problem installing vista, or 
centos on the machine.

It stops with a mountroot> prompt

before that I get error messages like

acd0: FAILURE - READ_BIG HARDWARE ERROR asc=0x08 ascq=0x03
Root mount failed: 5
no disk named 'adcd1'
setrootbyname failed
earlier it said:
BIOS CD is cd0
BIOS drive C: is disk0
and seemed to load the kernel.
What do I try next?