When slaving audio to an external address you must have hardware which allows you to also Clock the Audio System. For example, MOTU Audio interfaces will allow you to reference to an external Word Clock. If you do not update the audio with Word Clock it will eventually drift since it is not necessarily running at the same rate as the external source, but according to the computers internal Clock.

When Importing a QuickTime Movie and Slaving to External Sync we purposely mute the playback of audio in the QuickTime Movie. A QuickTime Movie will output it's audio through Sound Manager and currently Sound Manager does not have the capability to slave to an external timebase or Word Clock. Therefore, the audio in an imported QuickTime Movie will drift when slaving to external sync.

Work around:

If you have Digital Performer 2.5 and QuickTime 3.02 you can drag a QuickTime Movie to the Sound bites window and the audio will be extracted from the movie. You can then line the audio file up with the beginning of the sequence or your movie. If you have audio hardware and the audio is referencing to an external Word Clock the audio will not drift.