I have not yet had the chance to run memtest (Mathematica is churning in the background for a few days already).

However, I went back to an even older save that finally worked. It even had a small nuclear setup, also. Further, I have not experienced any new crashes in subsequent save/load cycles ...

I'm playing with the krastorio2 mod and I recently set up nuclear power.

Now, when loading a game (any of the 10 last autosaves and the most recent manual savegames) , the game crashes after a second or a few seconds (first freezes while it runs addr2line and then gives me the "Unexpected error ...