are you sure your running steam , i sometimes get that on won at a net cafe
my suggestion is to tweak your firwall settings & or reinstall all your steam games/mods & steam client
edit : hl1110 , heck , that's a won patch ,go get the steam installer from steam and go to register a product i alreay own , & then put in your cd-key and steam should then get all the nessacary files together , then presto , you got it