This crash to desktop occurred while the screen was zoomed in on my sovereign and a spider which was moving in between squares on the grid. I was preparing to take a screenshot when the game crashed, but I had not pressed any keys or moved the mouse in several seconds.

This game had two other issues which you may be able to find some evidence of in my core dump:
 - spider was moving in between tiles, on the gridlines, instead of on the tiles themselves
 - last sovereign was not findable; the whole map was explored, but the last sovereign and his city were nowhere to be found. I think they might have been on an island, too far off shore for the enemy city's border to be visible from shore, but can't confirm that.

Dxdiag, debug.err and core dump file submitted to FogBugz, case # 70798