videos slow down

everytime i watch a video i downloaded.it always slows down.the sound is going normally but the video is playing in slow motion

 

What video player and codecs you use?

 

windows media player+divx codec

 

Try VLC media player or install FFdshow and try with WMP.

What graphics card you have? How old/new is that pc?

 

i have a new computer with a radeon x600 graphics card.i'll try it on vlc player!thanks