No Luck!
I changed the refresh rate and multisample as requested in the setting.txt. I then started the game from the savegame file. The program still froze on 1 August. The music plays. The mouse moves around the screen. Animated characters stop moving. There is no response to mouse selections such as Diplomacy button, find province button, etc. I had to use the computer's reset button to get out of the program.
I then installed the recommended NVidia driver update. I restarted the computer again. Once the Windows desktop appeared, I closed all extraneous applications and then started the game from the savegame file. The program again froze on 1 August. The same effects occurred -- music plays, mouse moves, animated figures freeze, and mouse clicks are unresponsive. This time I was able to use the Window key to get out of the game and close it.
Any other suggestions?