There are several reasons this may be happening.
Virtual memory is on or RAM Doubler is installed. Note: If you are using Ram Doubler 2.0, Avid Cinema 1.0 help may mistake virtual memory for RAM Doubler and try to walk you through turning virtual memory off.
QuickTime 2.5 or later is not installed. QuickTime 2.5 or later must be installed in order for the Avid Cinema Extension to load.
For some reason the Avid Cinema Extension loaded before QuickTime 2.5. Avid Cinema Extension has a degree character in front of its name to force it to load after QuickTime 2.5. If this character is removed or changed so that the extension appears before QuickTime, it will not load properly.
The Avid Cinema card is not installed or is not seated properly. Follow these steps to reseat the card:
1. Open your computer according to the instructions in your Macintosh User's Manual. (If you do not feel comfortable opening your computer, contact your Apple Authorized Reseller for help connecting the card and ribbon cable.)
2. Seat the card securely in the connector on the system board.
3. Securely connect both ends of the ribbon cable.
4. If your model computer requires a screw to hold the card in place, screw the card down tightly.