Why windows vista wouldn't play video files

[timwireless]

I installed windows vista on a clients machine and worked fine with other application but plays video files in a slow manner, is it a windows vista problem or it might be something else and forgetting the drivers are installed

 

[Plumble]

Did you install video codecs?
That can make quite a difference.
K-Lite has most things you'll need. Worth a try.
http://www.codecguide.com/download_kl.htm

 

[timwireless]

every thing was installed as required, so I tried using another app, after analysis I discovered that if you restore the window to about 50% it plays the video without dragging the image but on maximizing the window the problem occurs unfortunately on the display properties one cant change the refresh rate any one with a solution are welcome