Can't load 'kernel' while boot for installation

Hey,

I owe a Dell Optiplex GX1 - which i try to install FreeBSD 6.0.

When i boot from the CD, BIOS drive CD gets recognized:

BTX loader 1.00
...
BIOS CD is cd0
BIOS drive A: is disk0
BIOS drive C: is disk1

then, the bootstrap follows


Loading /boot/defaults/loader.conf
/boot/kernel/kernel text=0x482d70 data=0x81140+0x9cb04
syms=[0x4+0x644b0+0x4+0x7a4fc)

Consoles: internal video/keyboard
BIOS drive C: is disk0


and here we are:
Can't work out which disk we are booting from.
Guessed BIOS device 0xffffff not fund by probes, defaulting to disk0:

can't load 'kernel'

...
OK _

What can i do, that i can install FreeBSD? Can i indicate cd0: on the
bootprompt?

BTW. i tried it also on 5.4 - same effect...

Thanks for your help.

Roger