Archive Invalidation issue. I can help you fix that.
Open your Fallout.ini in your Fallout New Vegas folder, as well as the one in your docs\my games\ etc.
Find your archiveinvalidation file in your data folder (Fallout - AI!.bsa or similar.)
Go back to your .inis and find this line: 'SArchiveList='
Type whatever file your AI is first, i.e., SArchiveList=Fallout - AI!.bsa, Fallout - Misc.bsa, Fallout - Textures.bsa, Fallout - Textures2.bsa, Fallout - Meshes.bsa, Fallout - Voices1.bsa, Fallout - Sound.bsa
Save and you're good to go.