Could anybody advice some troubleshooting steps to boot the Neutrino setup CD on this machine?

Dell Optiplex 760, CPU Q8300, 4 GB RAM, onboard video, USB keyboard and mouse. HD and DVD are SATA; set to ACHI mode.

Neither 6.3.2 or  6.4.1 setup CD can boot on this PC.
After the message "Booting QNX SDP..." (lots of dots) it hangs dead, does not even react to 3-finger salute. These CDs 
boot fine in VMWare.

I've restricted RAM size to 256 MB and one CPU in BIOS settings.
The FAQ adviced to set "non-PnP OS", but this BIOS has no such option.
Setting disks to ATA mode doesn't help.
Pressing ESC for altboot does not help.

Any idea, please?

- S.