QT10 should playback any movs originated from within mac without any problem. The fact that it cannot while QT7 seems capable of doing so strong indication that something went awry during installation. Of course, there is a slightest chance that you, as macbook owner, might got some peculiar problem with QT10, though I doubt it. Well, if it suits you, you may go just with QT7 and forget about QT10, as was suggested in previous post.
Everest Mokaeff
http://www.mokaeff.com