I have found my dvd drive unaccessable at times. Sometimes re-booting helped sometimes not. I also found (at these times) literally thousands of messages in the logs like this - “sr0: CDROM not ready. Make sure there is a disc in the drive.”. These errors happened every second whether or not there was a disc in the drive. A little web searching reveiled the culprit to be KSCD. Killing this process instantly made my dvd accessable again.
Also interesting - I don’t use kscd, never launched it, not in my autostart directory - yet still launched when I booted.
Obviously, I’ve removed it from my system. IMO: Such a buggy and redundant peice of software really shouldn’t be installed and launched by default. Smacks of IE/MS style imperialism! OK - maybe that’s an over statement, but makes my point!