>>> 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