This might already be a known issue, but the game across all civ 4 installations hate it if you quick load and save, in case you want a better result to an outcome. This likely do to the file integrity becoming unstable. I know some of you would shun this, because rl this or xcom that, but for those who struggle too, DON'T save scum!
edit: too many ands in one place
edit: too many ands in one place