I-movie is open resolution were I-DVD is not as open, so I would assume the problem is caused by the Avi codex (I wont bore you with the technical). I'm not familiar with I-move or I-DVD but with Avid I will always export the film as an mpeg-4 or similar file and then burn that on to a DVD. Trying to layoff to the DV cam could be a multitude of errors. And as a general rule post converting files can throw up even more problems i.e re match source, match frame, resolution errors etc etc.