Since the last patch, the game will crash/become unresponsive when ever the game window is minimized, I alt+tab, sometimes when auto-saves occur, or my computer does any other task that isn't ONI (such as a scheduled hardware or virus scan occurs).
I'm pretty sure it's related to switching away from ONI.
Hope this gives you a clue. There seems to be an inordinate amount of bug reports in the forums lately.
My faith in Klei is, while tested, still unshakable.
Alt+Tab out of window
Computer runs tasks other than ONI (such as hardware or virus scans)