Question Mark in Safari, Quicktime , Movies don't play, Mime settings
To Apple Discussions!
If you have no problems w/playing QT files while using Opera, then the problem could be w/Safari. You may wish to crosspost in the Safari Forums where the Safari users hang out so that they can see your issue & can possibly help you out. Sorry, I don't use that particular browser.
See if cleaning out the cache helps. That is the one thing I always here Safari users complain about.
Check QT Preferences>Advance.
Make sure "Enable Flash" is unchecked (disabled)
As for the QT MIME Settings not sticking, see if repairing permissions from your Tiger DVD helps.