As a follow-up, by doing different actions I have been able to continue playing the game from the save I provided above, but it is now crashing every 2 or 3 turns. These crashes always seem to be related to selecting or moving a ship or fleet. This has made continuing this game extremely unpleasant, so I am going to start a new game. I think this time I will try the Baratak Grove and see how they play.