After getting the common "excessively-long save/load times as you progress", I started alt-tabbing out of the game during said loading screens.

 

So I figure there's two strong possibilities.

 

1) Alt-tabbed during the load screen, came back in, then crashed.

2) I'd just swapped Sagani back into my party, and she was now 1 level higher than I was (due to Stronghold adventures).

 

I'd attach the error logs, but apparently I'm not permitted to upload that kind of file.

Managed to fix the issue by Verifying Integrity of my game cache via Steam.  Hope this helps anyone else with this issue!