RICHARD103  Well, yesterday all the iLife '08 upgrades came available from MacUpdate, VersionTracker etc., as stand-alone installers. Now we're getting somewhere, I thought. Somewhere bad it turned out. As with Software Update, the iMovie installer upgraded to the "more stable" 7.1 and the app would not launch. I guess if your idea of stability is inert you're good to go. And as to removing avc1Decoder & mp4vDecoder from the root library QT folder how would you know to do that? And why would it make a difference? It did nothing to make iMovie work for me. Do tech folk read these things or are we wasting our time here? Actually, iMovie 6 had some on-the-fly audio and video editing features I don't see in v.7.  
(Version 7.1)