Originally Posted by The Nemesis
In L4D2 it says the following will prevent you from entering secure servers
so I removed it and sourcemond is disabled :/
and in order to load plugins, you must have -insecure in launch options
Do what i did remove it load the game up and after it loades up verfi the game will play just fine then close the game and re-add the file and then reload the game try that it worked for me.