I'm getting this issue with dwarfs randomly going completely berserk and attacking other dwarfs, causing a loyalty cascade.
I've got a save. I haven't browsed the thread to find out, but is anyone else getting this issue?
Here is a link with the save file. I've modded the game just a bit (added a custom mineral and reactions for it), and I think that was the only change I made besides tuning down the siege triggers.
Before the dwarf flips out, he was ecstatic, not trying to make an artifact, so there's no explanation for it at the moment.
Was he that "Secret" dwarf? IE; When a dwarf enters the map, a combat report shows up ("R") with a report that a dwarf is in combat; For example; "Urist McSecret Eyes the Refuse Stockpile".
This always seems to result in that dwarf doing something bad in your fort;
(Spoilered for Spoilers)
A dwarf that paints a pentagram in blood will turn into a powerful demon, or a Refuse Pile-Eying dwarf turns into a necromancer, etc.
I remember getting a dwarf that "Talked Crazily to himself" Which sent him berserk, killing several dwarves before being killed by a random fire landmine (Incidentally, setting all the coal ore lying around on fire, causing !!FUN!!, and ending the fort due to this all happening near the booze stocks).
It would be possible that Urist McSecret went berserk near a trade depot and killed a merchant; Then another dwarf killed Urist McBerserk, causing a loyalty cascade.
Thats my idea, anyway.
(Also, I need to know myself, do these "Secret" reports EVER result in anything BUT !!FUN!!? Because i found that they became to annoying to handle and ended up atom smashing them on arrival, but then i just turned it off. Personally, i think it would be good if there was a chance of a positive result, giving me a reason to keep these guys alive and not just switch them off; For example, give Urist McPentagramInBlood a chance of turning into a friendly powerful-demon-warrior instead of just killing everyone, or Urist McTalksToSelf being a (whats it called? Someone who prys into other peoples affairs, sorta like a paranoid detective?) who, after completing his "special" finishes all outstanding crimes/reveals vampires. Just my 5 cents worth.)