Hooks & Under-Plane Swings?

[Travtex]

EDIT: Wrong forum, sorry!

So, since having completely obliterated my swing (In a good way, I guess -- Stopped blocking my hips short) I've developed some insidious pull hooks. At first it was just the irons -- Trying to fix that had me topping everything.

Spent some meticulous time at the range and made some progress. Though I noticed that I'd started hooking my driver as well. Nasty low duck hook, though my tempo tweaks seem to have dramatically increased my swing speed (It was 95, no clue what the increase is, or if it's just perception).

I noticed something that I think is the (Or rather, -A-) culprit. I get to the range at sunup, and my practice facility faces the east. I got a great view of my shadow dead-on out of my rear peripheral vision...

I'm perfectly on-plane on the backswing, but in the transition I'm doing a Furyk-worthy loop and dropping well under-plane. This seems counterintuitive, as my divots have tended to be more angled as if I were coming with an outside-in swing... but there it was, an obvious drop of 6-8 inches flat on the downswing.

Is this a possible 'The Hooks' culprit? What are some remedies?