Dutchfire sent me the save that he received from Churchill. This save consistently generates the endless loop at the end of player 4's turn. I went back and rechecked the save that Fed1943 sent to Churchill. It has NO problems.
Sadly, I still have no clue what is causing the problem or how to fix it. A search of the forum did not turn up any ideas either. Whatever happened, though, happened during Churchill's turn. Hopefully he can tell us if he noticed anything unusual. Unfortunately, it doesn't look like Churchill has logged onto CFC in the last several days.