During the installation of QuickTime 4, you are presented with 3 different install options:
By default, the Minimum option is checked. While Minimum is suitable for many customers, others will find that it does not install many QuickTime components that they rely on.
With a Minimum install, the QuickTime installer will remove the old QuickTime 3 extensions (as it should) and install the minimum QuickTime 4 components (including the QuickTime extension, QuickTime Streaming support, the QuickTime Plug-In, and the QuickTime player). PictureViewer, among other commonly used QuickTime components, does not get installed with the Minimum install option.
Because of this, certain applications that rely on those QuickTime components, such as the Apple DVD Player or applications that have the ability to show file previews in their Open dialog boxes, will not work properly. Furthermore, QuickTime Player will not be able to open certain file types without these additional components installed.
In most cases, QuickTime will display an alert that you are missing some components to provide you with comparable functionality and it should offer to download them automatically. However, this may not always occur.
If you are experiencing any of the above issues, you might need to re-run the QuickTime installer and select either the Full or Custom install option.