i downloaded a .avi file and when i try to open it quicktime just displays a white screen, and when i hit play the time progresses, but there is no sound and no display on the quicktime screen. Once it told me I needed to download something for quicktime, so i clicked the link and it took me to a page with a whole lot of different downloads for quicktime and I was not sure which one I needed. Does anyone know what is going on here?