DVD region codes are used to restrict playback of certain discs to a particular geographical region.
Your DVD-ROM drive must be set to the appropriate region in order to play the DVD. In Windows Vista, the DVD-ROM drive's DVD region can be changed as follows:
1. Click Start -> Control Panel -> Device Manager.
2. Double-click "DVD/CD D ROM drives” and then right-click the appropriate DVD drives and click Properties.
3. Select the DVD Region tab, make the desired changes and click OK
*Note: You must have Administrator privileges in order to perform this change.