for those who encountered this problem when you think your driver is updated and you already installed directx.
try this fix it works for me:
click windows icon on the lower left
right click my computer then properties
click system rating
click rate this computer
then wait for the assessing windows media decoding to finish.
or just see this guide on how to get your windows experience index
http://www.sevenforums.com/tutorials/26 ... score.html