If you get this message while connecting to any server try to do the following:
- Log out your Steam account and restart Steam, then Log in again.
or if above doesn't help:
- exit Steam and delete the following files from your Steam directory:By default, the files may be found at C:\Program Files\Valve\Steam\ or C:\Program Files\Steam\ (the location on your machine will vary if you specified a different installation folder, or if you have moved your Steam installation).
- Steam.dll
- SteamUI.dll
- ClientRegistry.Blob