Sorry pauly66 I got called away for a bit.
Okay first let's make sure libdvdcss is installed .. open a terminal and run:
and follow any onscreen instruction to let it download, compile, and install libdvdcss.
sudo apt-get install libdvd-pkg
Now, can you remove the DVD .. then reinsert it .. wait a few seconds .. then open a terminal and post the output from: