Current CD/DVD contents display with previous content in alpha groups

On one machine here, when I open (not auto-play) a CD or DVD, the Explorer
window shows the contents not only of the current disc, but also of
previously opened discs (each previous file having a shortcut icon).
Furthermore, the contents are displayed in alphabetical groups, with an A
header, B header, etc.

We also have trouble playing some discs -- a reboot is frequently required
before it will do the job.

This machine is only about a year old, and the DVD drive does not see heavy
use.

Anyone know what's going on with this?

--John Hupp