NEC 3520a problem reading dvd

I just got the NEC 3520a and installed it to secondary master. When I put a dvd in the player I get this message on my windows media player “window media player cannot play this DVD because problem occured with digital copyright protection” any suggestion on what is the problem? I’m very new to this computer stuff. thanks

In My Computer, select your drive and set the region to match your location.

Or use anydvd or dvd region free or other app to make your system region free