Here's the character at bind pose with default skin weighting:
Here, I just move the main shoulder/upper torso control over a little bit and rotate it:
Now, I just zero out that control to its default position, and it leaves the geometry completely destroyed:
Any ideas what could be causing this? I've been wrestling with it for a while now, and I'm at a loss as to what it could be. Soooo frustrating, and I can't afford any downtime since my thesis is due in a few weeks, so I really hope to sort this out soon. Thanks in advance for any help!