The video runs at a slow pace

Hello,
well i have jst done an osri now when ever i play any video , the pace of the video is slower than tht of the audio,,, like the audio moves on and the video freezes, sometimes skips,,, wht kind of drivers needs to be installed ,, m using winx service pac3,,, have already uninstaleed win media layer , thn installed the decoder too,, plz help