I've already sent in two bug reports regarding a crash to desktop that happens when the turn begins, but on a hunch (there was disk activity consistent with an auto-save and it seemed like the bottom of the screen flashed up 'Auto Saving' before I was dumped out) I tried turning off auto-saves.
I'm going to play a little while longer to check this out, but I think it's worked, though it beats me why that would be the case.