This only happened recently.

If I go to a server and they're playing co_rebirth or map changes to it.

It crashes my NS and saying error loading it.

I've tried to delete it and download it again from various servers and same thing.

Is there another file I should be deleted to get this to work, before re-installing NS again? Or just stop playing co_rebirth

I'd say first try reinstalling,thats all I can thing of

Maybe there are missing some models, which are needed for that map (or they are replaced by other maps data)-

I'd think you reinstall completly new.

yea i agree i think you should try reinstall of if this has happend in the new vertion of ns then try downloading the game from a differnt site and seeing if it works could be corrupt of something i dunno. but deff try reinstall.