Thanks Northern Wolf. There were no units with 0 movement, but there were a few Immobile units with the Go To and Explore flags checked. I unchecked those flags, saved, and reloaded. The game still stalls at the same point.
I noticed that my edited BIQ file was only 65kb vs the original 525kb. But everything is there when I started a new game!?! I don't know why my edited file would be so light, yet still have the full mod with all its starting units etc? So I deleted the original files (previously I had just renamed them as backup), restarted my PC and started a new game. The entire mod was there despite the disparity in file sizes?!? I'm confused.
Is there anyway to tap into something like an AI log so we can see what it's doing when it gets stuck in a loop?