This post should probably have been posted in Technical Support, so we'll have to move it there. =)
Beyond that, I'd like to ask the following:
1) If you reload the latest autosave and continue from there, does it still crash in the same spot?
1b) If it reliably crashes on the same turn on reload, please attach the savegame so that we can try to reproduce it here.
2) Do you get any message when you crash? If so, what message do you get?
3) Please attach your crash logs and dxdiag to help us better identify the issue.