Ok, now this is getting really wierd... I will try to be as descriptive as possible.
Following your suspicions around mods corrupting the files, I made sure I have steam stable selected, verified all files, loaded xenonauts launcher and deleted community map mod (which came pre-installed in steam version and was previously disabled by me), no other mods were installed ever.
Loaded Kainas.sav and landed with the dropship again. It did generate a slightly different map for me and I was able to make around ~10 turns or so and save after each turn.
After I mowed down enemy hordes outside and started breaching the battleship, suddenly, I could not longer save the game after turn ended - it crashes to desktop when I attempt to save.
I got curious, and started experimenting. I loaded all the previous saves one by one from the moment I landed on the mission and tried to save the same turn again, but crashed immediately to the desktop.
So in summary, I was able to land, made multiple turns and successfully save each turn without crashing through out the mission up to a certain point, and I am able to successfully load those saves. Subsequently, after I encountered the first crash to desktop incident in the mission, I can no longer save after successfully loading any of the previously made mission saves.
Here is the last quick save I was able to make before crashing starts happening. [ATTACH]6107[/ATTACH]
Here are two combat saves I made successfully without crashing during the mission and which I am able to successfully load, but crash when I try to save even without ending turn first. [ATTACH]6108[/ATTACH][ATTACH]6109[/ATTACH]
Here is the landing save that was created for the mission. [ATTACH]6106[/ATTACH]
Ps. I do not mean to brag, but I keep my pc in good order, anti-virus, software/hardware firewalls, patching, up-to-date drivers, etc, so the likelihood that my machine is causing this is rather small.
Pss. Let me know if you need anything else from me. I wish there would be some sort of debug log I could give you, want to finish this game, really liked it thus far
LaNding2.sav
Quic.sav
Combat1.sav
Combat2.sav
LaNding2.sav
Quic.sav
Combat1.sav
Combat2.sav