1. Ensure that your are attempting to open your DVD file with the right Windows Media application. Close out of Windows Media and then reopen the program and try to play the file again. If you receive the same error message, continue on to the next steps.
2. Read the information on the file you are trying to open, and make sure that your file is the only one needed and that it is not part of a series of files (like part 1 of 3). If it is a part of a series, you will need to download all of the files for your movie and then try to play the file again.

3. Download the InterVideo DVD XPack plug-in and follow the installation instructions if you are running XP on your computer. The InterVideo DVD XPack will decode your DVD and provide Windows Media with any additional codecs that might be needed to play it.
4. Install PowerDVD SE for Windows Vista if this is your operating system. This will provide everything you need to play your video files.