I had a savegmae (imaginatively called "1") which was a campaign save. After getting crushed in the campaign, I decided to start a normal game. When I reached a point I wanted to save, I figured I could just overwrite that save since I was going to have to restart the campaign mission anyway.

Unfortunately, the game still thinks "1" is a campaign save game (you can see this by the bottom of the loading screen), while it isn't. If I try to load it, GalCiv 2 crashes to desktop. It never crashes under any circumstances (that I can find)