Sometimes Windows will lose a drive as the registry becomes cluttered with leftover bits and pieces of left over programs. I think your drive was working Prior to this point.

Here some links that may help:

Under “My CD drives have vanished (from Explorer, Device Manager, etc.)” in following link you can download a small free program called "cdgone" also works on DVD drives.

http://aumha.org/win5/a/xpcd.php

Or better yet rather than listing links, do a google search for cdgone and you will find more valuable information as there are forums etc that will show up in the results. I know there is a good article on CDFreaks about upper and lower filters around the drive driver. It will probably be easier for me to find it and post a link that tell you where to look.

Mack