Cant get on the servers with people. Help

[T_Azik]

So i can get on empty server(tried only with one). But if i join on servers with people it writes me: "Your game files do not match the server's. Try verifying your game cache in steam, or maybe an update just came out."
Didn't played for long time, and when i enetered the steam it wouldn't download the update(or it weights 1 mb. so i didn't even saw how it was downloaded. I notice, that it's set to auto-update on steam. Also i dont know how to verify the cache.
Please help.

[Azure Zero]

Verify:
Right-Click on Game
Select Properties
Enter Local Files tab
Click Verify Game Cache

I would recommend posting this on the NS2 Technical Forums for better help