Something is wrong with the localized_English_iw03.iwd file. Just redownload it...
How to redownload it:
Delete the file
Open your steam library
Right click Black Ops Multiplayer and press properties
Under the Local Files tab click Verify integrity of game cache.
Then steam will redownload the file you deleted
it also could be you fucked up one of your textures dont worry it happened to me
/marked as solved
Should fix it. Post here if it worked or not.