I was a level six, I had enough built up level ups to reach level eleven BUT I WAS STILL LEVEL SIX. That last bit is important. I'd been in Whiterun doing little quests here and there for people before I was going to LEAVE Whiterun and head on down to where the entrance to the Dawnguard area is.
So I gave one last look around Whiterun, everyone was alive and well. And I left. I got to the road leading up to Black-Briar Lodge(?) where you get Frost. I decided I was far enough away and did my level up. I saw that I was close to level twelve and decided to kill the guards again at BBM. Upon exiting a courier delivers four, FOUR, letters of inheritance from Whiterun. Adrianne, dead. Carlotta, dead. Ysolda, dead. Breuin, dead (how the hell does a beggar have any money to give).
And no it wasn't a dragon attack, I hadn't even fought the first dragon yet.
I'm on the 360. What the hell were developers thinking with this crap? I wasn't even in Whiterun HOLD when I became level ten, let alone the city itself.
They need a patch to disable the city raids until they can fix it so that the vampires don't massacre the entire city while you aren't even there.