Can you PM me a debug from your VM (system->advanced->save debug)? I can take a look and get you sorted out.
I really appreciate the offer. However, it looks like there's a lot of information in the debug, much of which I can't share (user accounts and such) since I'm testing this in our production environment. We generally have to have a BAA or something in place for that.
With that said, I'm looking through the debug information to see if anything stands out. I've also started reading your SMB permissions overview which is pretty great! Thank you for that too!
Also, it looks like we have about 80,000 user accounts on the domain, so that likely has something to do with it...