Last night my wife and I slipped a DVD into our Ubuntu multi media computer and watch a good movie.
This morning I ran updates (apt-get update and apt-get upgrade).
Later when my Grandson tried to play a movie he picked up at the library, it wouldn't play. The error message read:
"An error occurred. Could not read DVD. This may be because the DVD is encrypted and a DVD decryption library is not installed."
The multi media system is running Ubuntu 12.04. Had the same issue with my wife's computer which runs Ubuntu 11.01.
Did a quick search on the internet and found that other experienced the same issue, and the fix was simple.
Word Of Caution - Do to copyright laws, this program may not be legal in your country
1. Go into terminal mode
ctl Alt t
2. Install a package named libdrdread4
sudo apt-get install libdvdread4
3. Run the following script:
sudo /usr/share/doc/libdvdread4/install-css.sh
After a reboot the dvd played just fine