Black helmet palace guards

[Richard Knight]

A weird thing is happeneing in TES4 Oblivion, all the Imperial Palace Guards are wearing a black helmet, why?

PS. I'm not using any mods related.

 

[Jamrock]

Not using any mods RELATED?

Or not using ANY mods AT ALL?

Don't know of anything in plain ol' vanilla Oblivion that would cause a strange error like that.