I use the Steam version.
It only happens with my main character.
When I start and play the game the first time there is no problem.
But after I close New Vegas, the next time I go back to play with the character his head skin color does not match his body skin color.
The body get a yellowish darker color, and I think the head color gets lighter.
I've tried changing bLoadFaceGenHeadEGTFiles=1 in the 3 .files (steamapps & my documents), it does not fix it.
It happens when I use Nexus Mod Manager and also when I use the default launcher.
These are the mods I use, but none of them change the caracter skin or textures.
I wish I could post pictures of it, but the forum does not allow it.