Severely screwed up maps.

I'm kind of at a loss as to what's going on here.

I've exported a high and low poly model with correct UVs out of ZBrush. The Normals aren't flipped. As far as I can see it should all bake out normally. Instead I'm getting millions of missed rays and maps like this:

I'm probably forgetting something important but I'll be damned if I can see what it is.