Unable to connect to any server

[mager56723]

What the title says. I can't connect to any server and the game displays This error message:

Client disconnect, Unable to authenticate client


Any ideas?

DX Diag:
http://pastebin.com/wJX4mrvA

[FM_Jarnis]

Generally that error means that communication between you and Steam is somehow disrupted and the server thinks you don't have a legimate copy of the game.

Could just be case of restart PC, restart steam, login again, retry. Could be something related to firewalls or stuff like PeerGuardian/PeerBlock.