The program on the Apple Education Resource CD that will update and/or
install the QuickTime 1.6 extension isn't working correctly. It keeps
the old copy of QuickTime 1.0 in the Extensions folder within the
System Folder and just adds QuickTime 1.6 into the Extensions folder.
The program doesn't replace the previous version of the QuickTime
extension. When you restart the computer a message will appear saying
that the QuickTime extension isn't available.
Remove the old QuickTime version from the Extensions folder within the
System Folder to work around this.