Thanks for having a look folks. I will try out a fresh campaign.
As for hardware being an explanation — I have several save files from the same many-hour session one evening (hey, it's a good game). All of them are corrupted. So it seems to me like the in-memory state of the game had a problem, and every time it was written to disk that problem was written too. If there was a hardware issue with the disk, I would expect only one of those saves to be corrupted. If there was a CPU issue the crash would surely have been during the session, not while trying to load it later. And if there was a memory issue I would think the same reasoning would apply. Just my thoughts about what it looks like from the outside.
