Okay, so things just got even weirder. I went to my desktop to play Dom instead (my issues so far was on my laptop), since I've got an older copy installed that that I know exists. I thought. Because now copy-protection sets in there too? I haven't even started Steam, the game is installed at C:/Dominions, and I've never had issues there before, having several saved games that I've played for 100+ turns.
And I haven't patched the game there, didn't even have steam running at the time of playing! How would that even work, on a technical level? This is going from slightly annoying to truly frustrating. I have such a Dom craving! What to do?