I upgraded to Quick Time Pro from the Apple website; it was playing files ok, until I tried to play an old sporting event taped from the TV that was encoded as "MP4". I got the audio, but no video. Does QTP play MP4? Do I need any other plug-ins?? Is it the fact that it was a taped TV show that doomed the video feed? Strangely enough, I was able to play it on another video player that I downloaded for free from a "free Mac software" website. What gives with QTP??