Problem with playing studio released and backed up DVD's

When I insert a DVD (Napolean Dynamite, etc...) I get the following message:

Windows Media Player cannot play the DVD because a problem occurred with Digital copyright protection.

When I insert a backed up copy of a studio DVD the video will play but I get no audio.

What should I do?

Thanks,

allmanbro

 

Oh, by the way I am using XP Media Edition operating system