This was what we also thought. But when the electrician came he meggered everything at the panel for Hot-ground shorts and found absolutely nothing. Also the freezer was in perfect shape (no hot-ground/neutral-ground/hot-case/neutral-case connections). Also it didn't matter what load we switched on. Was it the freezer, the brand new electric range or anything else, even with the other breakers turned off the GFI tripped.
Keep in mind the neutrals weren't fused!
