DVD ROM woes on Ubuntu 12: mount /dev/sr0 no medium found

I recently upgraded from Ubuntu 10.04 to 12.04 on a server used for ripping and encoding DVDs. About a week after doing so, the server started acting up with errors about /dev/sr0 no medium found and failing to mount the DVDs. Thinking the CDROM was bad, i swapped it with another. Same problem. I removed /etc/udev/rules/70-persistent-cd.rules and then it worked! one time… then back to the errors. Rebooting seemed to allow it to work, one time. But even that is no longer working. Searching around, it seems a lot of people have had this problem with recent versions of Ubuntu.
I may need to try another DVD ROM, maybe both of these are bad?
Or else I will try reverting to 10.04