Lost sync roundtriping FCP Soundtrack Pro

Hi all.

I´m having a delicate problem.

I've just upgraded to FCP 7 and all of a sudden when I send an audiotrack to soundtrack,
save it and go back to FCP the sync is lost. The audio is up to a second off at the end of
my 3 minute film.

I have trashed the prefs and set everything back to 25fps in soundtrack but that did'nt help.

Right now I'm unable to use soundtrack as my audio mastering tool anymore which is
a VERY serious problem. I have never had this kind of problem in the previous version.

Any thoughts on this would be most appreciated.

Göran