Yes, I think that updating Miranda is a major reason for Facebook misbehavior (suspicious activity, change passwd, etc.).
I just got back to Facebook (and to Miranda) after a month spent mainly offline. As soon as I updated Miranda, Facebook kicked me out. Before updating, I had gone offline with Miranda, hoping to minimize the risk of problems. However, going offline before updating didn't help. It's as if Facebook knows about my Miranda changing even if I keep it offline?
I wrote another support ticket to Facebook, polite and factual, without mentioning Miranda or even "other browsers". I just said I'd been locked out again, forced change my passwd, inconvenient, blahblah. That makes about 7-8 messages to support.
Unfortunately, I don't have a netlog of the event, because after time passed, I had given up on keeping logging active. My bad.