Hey,
I've had this happen a few times now. It took me a few tries to get it, but I found that when I pushed the "Eject" button on the remote or component before the "Reading" logo is up for more than a few seconds, it ejects.
Step By Step:
I turned the system off > turned it back on > just after the red "Pioneer" logo clears (when the tv picture comes back and the "Reading" caption appears), push the "DVD Eject" and wait a few seconds > the tray ejects.
Regards,
Marc
September 2006