Type of bug: Graphical, possibly script-related, asscoiated with being a Khajiit and a werewolf
I've heard a report of a bug where if you are a Khajiit and you change into a werewolf, you may end up with the default body of an Imperial with the head of a Khajiit when you revert back, and the game will recognize your character as an Imperial. Reloading, curing yourself, becoming a vampire lord, and using the face-changer NPC don't work, with the latter causing the game to freeze from what I've read. In other words, if it happens, it happens, and there's no fix at all. This has been observed when you become a werewolf for the second time as a Khajiit, so it is unknown at the time whether or not other races like Argonians are affected or if the acquisition of lycanthropy through the vanilla quest is or can be bugged as well.
Further testing should be done in order to gauge the extent of the seriousness of the bug (such as which races are affected, does this affect ALL Khajiit characters, etc.).
More information can be found here: http://www.gamesas.com/topic/1391019-werewolf-as-a-khajiit-human-body/