I do not thing codecs are the problem. Let's take the example of shell32.dll. Here the AVI resource with id 165 is playing in Vista, but the one with id 162 (the Avi one sees when files and/or folders are deleted) is not. When I delete a folder, I do see the animation (so I presume the codec is installed); when I want to play the animation in another window, I only see the background.