So I tried to play Left 4 Dead 2 today. Everything goes fine, I join a lobby, choose my survivor, etc. Then it loads. The load ends and I'm greeted to a black screen that flashes every now and again and audio of horrendously lagging sound effects (ie. half of a gunshot, over and over and over). I hit the windows button, go back to my desktop, and I am unable to close L4D2. I open task manager to end it. I confirm. It does nothing, so I have to restart my computer. My internet connection is fine (obviously) and the game worked perfectly a day ago. Since Steam Support is totally useless, I turn to the Escapist and ask, does ANYONE know wtf is going on and how I can fix it?