I was doing the Cloch fight inside the mines, and set up a lot of traps / blockades against the enemies coming in from the big room. Eventually an enemy swordsman walked into an ironjaw trap and died... after that, the game got stuck in the enemy's turn (hourglass cursor). The UI was still functional, but the only way to progress was to quit to the main menu (surrender was also greyed out).
I'm playing the latest steam version (v1.03).
Sorry about that! I think I've got that fixed now; it'll be in the next update.