Mine happened when I accidentally killed most of Dawnstar on my Vampire assassin. I was heading to Dawnstar for the
Spoiler DB quest to hunt down Cicero
and had Shadowmere and the Spectral Assassin with me. However, I had also forgotten that I was a Stage 4 Vampire. As I enter town, a nearby farmer spots me, shouts a battlecry and charges, meeting my Spectral Assassin in battle. I watch as more citizens and guards start to advance on us. Without thinking I get off Shadowmere who then charges into the crowd and starts beating up a guard. So, I decide that I don't really want to fight all of Dawnstar so I leave Shadowmere and the assassin there and start walking around the town. And then I hear the beating of wings. I look up and, sure enough, there's a dragon bearing down on me. It's already fried some of the town and it then lands in front of me as I start hitting it with the Mace of Molag Bal. Finally, as it's almost dead, my assassin comes out of nowhere, jumps onto the dragon's head and stabs it with his dagger, killing it. Shortly after Shadowmere joins me as well. So, on the bright side I killed a dragon, but on the not so bright side, most of Dawnstar is dead,
Wow, that was long. o_o
EDIT: I've also experienced the Mage College bed stealing, but with different NPCs. Apparently being a member of the Mage's College destroys your respect for bed ownership. Too bad my character is still crippled by his ability to psychically tell whether someone owns a bed.