I’ve had this issue with DVD Studio Pro for years. Before I run anything through Compressor I always remove 4 frames of audio from the top of the soundtrack and that drops the end result back in sync.
Unfortunately it seems to me that in DVD ST Pro one can advance the sound in the view window thingy, but not the picture.
So minus 4 frames sound works for me. You are talking about “a second or two” – but maybe you don’t mean that to be taken literally.
I have never received a proper explanation for this except that once someone told me that this occurs only when progressive picture is being used.
If anyone knows why, please post.
Best
Harry