I had bombarded a planet until the population was gone, but a facility survived. I decided to invade and got a range check error.

One crash later, I decided to load an earlier game. Range check error on startup.

Reinstalling did not fix error. I think there is a corrupted last game played that is stopping me. Deleting saved games did not save it.

I noticed that I cannot change the game's video resolution settings without an error now(whether to be windowed or have a fixed resolution). So I think the data I need is where that is stored.

TL;DR Where are configuration settings or last game played saved?