Export audio out of sync

Hi,

I've cut a trailer on FCP 6.0.4 and while it plays down in the timeline perfectly, whenever I try to export it certain shots are played back wrongly. It would seem that the picture in certain shots has slipped several frames from the audio in the export.

I'm 90% certain that most of the problem shots are from the same clip. However, I'm not sure without going frame by frame and eyeballing the whole thing. The problem shots are obvious because the clip is from a pre-edited tape rather than the rushes and I used every frame I could, so even one frame slipped is a very obvious disaster.

It's as if the timeline is displaying one thing, while the source quicktime is actually something else. I first noticed something strange when I was trimming in the time line. The preview shot in the monitor would not be the frame that it would show me in the timeline.

I've dumped the render files and re-rendered everything and it doesn't seem to make a difference. It doesn't matter if I try copying the sequence to another project, or relinking the media. Nor does it matter what kind of quicktime export I try. The shots are still perfect in the timeline, but out of sync on the export.

If anyone can help, I'd appreciate it!!!