Ah-HA!!! ding ding ding... we have a potential ~winner~!!! Even with as near of a match to a previous mod-set as is humanly possible, the game for whatever reason, finds it very difficult to run again off of an old install's Save folder, especially if on a new computer. So "yes", that would be my primary suspect now. Try copying and / or moving the Save folder to keep it away from an experiment, so that you can pull it back in later, if this test fails. Once you have the Save data "safe", delete the current Save folder, re-do all of your in-game settings etc., and try again.
