The Imperial Legion quest, Suryn Athones' Slanders, requires you to kill an Ordinator in the Hall of Justice. When you talk to him about his slanders, he insults you and then attacks you. Ok. But there are 3 other ordinators in the room, and they immediately attack you too, even if you haven't even drawn a weapon or attempted to defend yourself! If you manage to survive fighting 4 ordinators at once in a small room, you end up with a 4000 bounty, even though all you did was defend yourself from an unprovoked attack.
I've never done this quest in Morrowind, so I don't know if that's how it's supposed to work, but I doubt it. I've noticed that NPC aggression is kind of a problem in general. For example, in several places all the enemies will start fighting each other as soon as I enter the cave/tower/etc, and I only have to kill the lone survivor. Maybe this is something like a bug in the faction assignments or a problem w/ using the Oblivion AI with Morrowind NPCs? I don't know.