Yes, I had cleared the cache before (a few times, actually) and this, as far as I can tell, was not happening sometime before, but I think may had started when I moved from 4.0.6 to 4.0.10, perhaps (I wasn't clearing the cache between the different 4.0.xx releases, only whenever I ran into problems independently of the release, but I did have to clear when moving from 3x to 4x and a few more times ever since).
And yes, clearing the cache solves the problem, and re-covering the (old) cache from a backup creates it again (of course, not something I need to do, it was just to verify that it was the cache content the trigger of the crash).