The QuickTime MPEG Extension is not currently compatible with older hardware based MPEG playback solutions. If you have an Apple or third-party MPEG hardware playback card installed in your computer and you wish to continue to use it, you should remove the QuickTime MPEG Extension from your Extensions folder.
For more information on the QuickTime MPEG extension, please see the following Tech Info Library Archive article:
Article 21026: "
QuickTime MPEG Extension: Read Me Document"