afoaa

This bug is caused by a conflict with a vampire script in the /data/script folder that probably originated from a vampire mod created before dawnguard. It doesn't help to uncheck the ESM/ESP. I solved the problem by installing one of the new vampire mods created to fit with Dawnguard: http://skyrim.nexusmods.com/mods/5863. The mod changes how vampire works (for the better IMO) but it also remove any conflict with Dawnguard and earlier mods so I can highly recommend it.