Windows Vista - http://www.vistaarticles.com
DVD does not Appear in Correct Aspect Ratio
http://www.vistaarticles.com/articles/264/1/DVD-does-not-Appear-in-Correct-Aspect-Ratio
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Published on 12/10/2006
 
When you view a video DVD in Microsoft Windows Media Player on a Tablet PC that is running Microsoft Windows Vista, the video may not appear in the correct aspect ratio.

DVD does not Appear in Correct Aspect Ratio
To work around this problem, set the display to landscape mode.