Strange, packet command initiated yet DRQ isn't asserted

I have installed a second-hand NEC NR-7800A CD-RW on a machine with a new install of 7.3, but although it is found on boot, it is not useable. dmesg has several lines giving the above message. The only recent reference to this on the list (http://www.netsys.com/suse-linux-e/2001/11/msg02197.html) suggests that this points to a hardware problem. Has anyone else come across this message? Happy Christmas to all! Kevin