audio levels in timeline vs in export -- something is funky.

Hi -- my edited sequence is perfect. I have vo, music, and everything is right. Somehow though, when I export the sequence, the levels jump for a few seconds such that it just gets louder all of a sudden, as if the levels had been key framed up .. but indeed they have not been ... and they sound fine inside Final Cut. I can't figure out why this would be ...

I tried:

- restarting
- trashing prefs
- copy/paste sequence contents into new sequence
- creating a new empty project and dropping the sequence in
- trash render files and re render
- log in with different Mac user (for some reason this sometimes fixes my render bugs)

All this to no avail. So how can it be that something that sounds right in the sequence can sound wrong on the export??

Many thanks.