Well, having figured out that disabling the third-party KTYS scenery made the problem go away (even though the scenery had been enabled and working fine for months), I've removed it and found an alternative KTYS scenery. Crash detection is back on, and everything's working fine again. Yay! Treetop64: I'm obviously not as experienced as you; I do still crash sometimes, and I haven't got any third-party software to monitor that and keep me on my toes. Hence the crash detection is worth it to me, even if there's a little performance hit. My framerate is externally limited anyway, and my system is more than powerful enough to keep at or near that frame rate limit at all times, so there's no downside performance-wise. This "building collision" problem is the first issue I've had with it, and since that's now resolved, I'm happy enough leaving it enabled. Thanks for the advice though!

Glad you were able to find and fix the problem! Best regards,Jim