Your game files do not match the servers....

Hi guys
So I just fixed the downloading mods fiasco and now I have a new problem. Half the servers I attempt to join hit me with this message
Your game files do not match the servers. Try verifying your game cache in steam or maybe an update just came out.

I verified integrity of game cache and there was no problem. Thus I'm wondering what else I need to do to get this working.
thanks