Probably your Easy Setup (default sequence) time-base is not the same than the one sequence you are editing.
Before importing the Zoom files, change the default size to one with the same time-base you are editing your movie.
That's an old FC Bug. When you import Audio, FC treats the file as they would have the time-base of the default sequence. So when you bring those files to a sequence with a different time-base, the audio drifts.
rafael
http://www.nagavideo.com