When you transfer a large amont of units with Astraeus let's say 400, it will be more likely to cause the game hang(pause for 1 min or so). I know the hang is random, but it seems to have more chance to happen when I do mass space move. Is that a coincident?
Which reminds me, there does currently seem to be some kind of bugginess with some orbital transfers where units are dispersed over a wide area/large number. It has occasionally caused crashes for me personally. Really should head over to the bug tracker to ensure this is listed properly but I've not yet actually tested to confirm my initial suppositions here yet. Edit: listed here on the bug tracker.
Now it's not really a crash. Be patient, sometimes it will be fine after waiting for a couple of mins. So I am not sure what to blame.