Here's a proper thread on how to fix those textures;
1. Go to the location of your Black ops "main" folder,
so; mine is (C:\Program Files (x86)\Steam\steamapps\common\call of duty black ops\main)
2. Locate and Rename all your modded files so mine was "iw_11.iwd" that was giving me errors, i changed it too "localized_English_modded_iw_11.iwd". then reloaded the game and it worked, but i overwrote the original iw_11.iwd with the new one that steam had provided/downloaded.
~ D0h being first one to post it. (external site)