DVD playback requires more stringent checks to comply with the latest Macrovision requirements. Macrovision is mandated copy protection standard for DVD-Video. If Windows Media Player detects a TV encoder on your graphics card that does not support Macrovision, you will get the "Windows Media Player cannot play the DVD because a problem occurred while configuring copyright protection" error message or a similar message. You will get this message even if you are not using TV output. The BT868 and Conexant CX25870 TV encoders do not support Macrovision. If your graphics card is equipped with one of these TV encoders or another model that doesn't support copy protection, it will not support DVD playback with Media Player.
Under some circumstances, updating your video driver can give you DVD playback, but a limitation is that you will not be able to output to your TV when a DVD movie is playing in the background.
Please download the latest drivers for your graphics card to attempt to workaround this issue.
If there is no workaround we would suggest a new graphics card based on the GeForce 6 series or newer GPUs.