There are two ways I think you can do this. The easiest is to reinsatll Windows media player: start > settings > control panel > add/remove programs > windows components > untick windows media player > next etc etc Reboot then repeat except tick the windows media player. This should set all the associations back to media player (except quicktime .mov films). The second is more long winded: right click My Computer > explore > tools > folder options > file types > then go down this list and make all media files (.cda, .mp3, .mpg etc) "open with" media player instead of quick time.