Disconnect:Error Invalid steam user ID ticket

I keep getting this problem whenever I join a public server. I get disconnected with a message saying:
Disconnect:Error Invalid steam user ID ticket.

It only started becoming a constant problem yesterday. I’m getting the same problem with CS:S too.

Restart steam

I’m getting this exact same problem, I’ve restarted steam.

http://supportwiki.steampowered.com/wiki/Game_Error:_Invalid_Steam_UserID_Ticket

It says one cause may be someone using my account somewhere else. :ohdear:

Delete clientregistry.blob