A couple of times now ive had an issue where ill be fighting an NPC and all of a sudden their health bar will disappear, they wont die but they also wont fight back. This gets in the way of certain misc quests like "Go here and kill X" for bounties and such.

Heres a picture as an example (yeh i know its bad quality but hopefully it conveys what i mean - Dragon, no health bar,not fighting, just glitched in the ground)

http://s706.photobucket.com/albums/ww64/Terda/?action=view¤t=001.jpg

anyone else had this?