No subject

(although this does seem to explain what you are experiencing) some drives 
are region locked by the firmware, i.e. even in Linux you can't read the DVD. 
Others will let you read raw data or will unscramble one region for you.

There are a number of sites on the web which deal with re-flashing your DVD 
drive (note that there is some risk involved in this). This can be used to 
reset your drive if you have the type which you can change 5 times. Sometimes 
you can change to a firmware which is either regionless or has a limited 
number of resettings.

What kind of drive do you have? You should be able to find out from your proc 
file system (it also tells you at Linux startup). Mine is:

tj at kandinski:~$ cat /proc/ide/ide1/hdc/model
UJDA540
tj at kandinski:~$ 

Anthony