There are two ways to fix this.
1) Temporarily remove the "textures\characters" folder.
2) Use the BSA Extractor to extract the missing textures into the "textures\characters" folder.
For option #2:
To extract all of the character textures, you'll need to use something like FOMM BSA Browser, and open "Fallout - Textures.bsa".
Once there, extract the following textures to your "C:\Program Files (x86)\Steam\steamapps\common\fallout new vegas\Data" folder (or wherever you have your FNV installed).
Basically copy every file extracted file to "Data", buy skip over the files that are already there. You simply want to fill in the missing files, but not replace any ones from hi-res mods.
Examples:
Textures/characters/male/handmale.dds
Textures/characters/male/handmale_1st.dds
Textures/characters/male/handmale_1st_n.dds
Textures/characters/male/handmale_1st_sk.dds
Textures/characters/male/handmale_n.dds
Textures/characters/male/handmale_sk.dds
Textures/characters/male/headhuman.dds
Textures/characters/male/headhumanm10.dds
Textures/characters/male/headhumanm10_n.dds
Textures/characters/male/headhumanm10_sk.dds
Textures/characters/male/headhumanold.dds
Textures/characters/male/headhumanoldm10.dds
Textures/characters/male/headhumanoldm10_n.dds
Textures/characters/male/headhumanoldm10_sk.dds
Textures/characters/male/headhumanold_n.dds
Textures/characters/male/headhumanold_sk.dds
Textures/characters/male/headhuman_n.dds
Textures/characters/male/headhuman_sk.dds
Textures/characters/male/upperbodymale.dds
Textures/characters/male/upperbodymale_n.dds
Textures/characters/male/upperbodymale_sk.dds
etc., etc.
...
BSA Browser Example:
