Here's an odd bug- occasionally (and I mean very occasionally) all enemies and friendlies stop being "working", even in single player. Their idle animations play, you can still push friendlies around by walking into them, but they stop reacting to anything.

Hostiles can't be targetted, nothing patrols. Clearly there is some collision detection still running if you get close to them, as they play the little contact animations. However, the game just sort of grinds to a halt.

Framerate is not affected at all. It can happen even in singleplayer. It's weird- nothing looks all that broken, it's just like events are no longer firing. 

Here's a short clip:

https://www.youtube.com/watch?v=FGd-lwLIHwk

(This was in a Viridian normal Void Crusade, the node just to the left of the Difficulty/Life Count scoreboard)

Sadly, this one is very intermittent. I haven't been able to nail down a precise repro case for you. If I do, I'll try to remember to update here.