Do you mean LW or QuickTime player shows a white screen? QT player is not always reliable for playback. I'd recommend using VLC - (click on link) _ (choose nearest mirror site) for previewing. To make it your default, select an mpeg/mpg file, press command-i (⌘ i ), & change the program to open it & then select the Change All option. You'll need to do this for whichever video types you're having problems with such as avi & wmp, etc.