Does 'eject' work from the command line at all on your system?
Yes and no.
The eject command works great to open and close the drive tray --- until I insert a disk. When I insert a disk and the drive tray closes, the eject command stops working. When I use the drive button to eject the disk, the eject command thereafter starts working again.
Hence my previous comment that there might be some kind of soft lock occuring.
But TDE does not have any control over the operation of the system-provided eject command, nor does it have the ability to lock access to the CD drive. Can you use the eject command with a CD in the drive from within KDE4 or XFCE?
This is very likely a kernel problem: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/986845
Tim