I had the error message maximum number of secrets has been exceeded. My dvd/cd drives were not detected. Tried a format of my Hd reinstall to no avail. In the end I downloaded
RootRepeal (free) - http://rootrepeal.googlepages.com/
As mentioned above ran a scan found and deleted a few processes that had spuriously long names.
e.g. ghyxvhjgjh that were running from the system32 directory. These were not got rid of with a fresh xp install. Deleted them rebooted and voila. Imgburn picks up both my dvd roms again.
I am sure I picked up the bug whilst installing some kind of video player software. I hope this helps.