After choosing to shut down, the GUI exits and text mode resumes, showing various non-consequential output messages and then a green notice (with timer) instructing one to remove the CD from the drive.

Unfortunately, Knoppix refuses to release the CD, in spite of pressing the open/close button on the drive.

If I press the PC's soft-boot button (a reboot), the drive opens just fine.

Ideas? Gracias in advance.