Audio Drifting When Exporting Quicktime Movie
 

This is strange and just started happening this week. I edit a 30 minute program and at the end I export the entire edited sequence as a Quicktime movie using the sequence settings. Toward the end of the exported quicktime, the audio starts drifting off late about 5 frames or so. I've done this workflow for years now and this has just started. The sequence plays fine and in sync the whole way through from the timeline. It's only the exported Quicktime that drifts. Working with XDCAM EX 1080p 30 material and trying to export as a Quicktime movie in that format.

Any ideas?

EDIT: Forgot to mention that this is Final Cut Pro 6.0.5.

Out of curiosity was this with the very latest update of QT? (7.6 I think it is). I'm XDCAM and FCP etc. but have resisted upgrading from 7.5 as I'm in the middle of some big projects right now.