OK so here's a not too common problem, one that I thought was peculiar to my setup (Ubuntu Linux on a PowerPC chipped Apple G5
Apple in their wisdom do not give an OPEN button on the CD drawer - in fact they hide the whole darned thing behind a sliding door which opens to reveal the CD drive
So…. The only way to open the drawer is to fire up a terminal (CTRL-ALT-T) and type in "eject" (hitting return)
It used to work, then stopped. All I got was some drivel about the CDRom not being there, or not being a block device. Whatever!
Try typing "eject /dev/sr0"
If that works you seem to have lost the link between sr0 and the CDRom drive
Open up a terminal (CTRL-ALT-T) and become root (type sudo -i then enter your password)
Now type "cd /dev" to put you in the /dev folder
Then type "ln -s sr0 cdrom" to create a simlink (or link) between your sr0 drive and your CDRom drive
Type "exit" to relinquish root previleges then type "eject" to see if it works - it should work
Answer curtesy of the Fedora Forum - couldn't find anything helpful on the Ubuntu Forum