Hello guys, I just bought L4D2 from Steam and today I decided to start playing. As a new player, I thought it is only fitting that I should start the offline campaign on Normal difficulty. All was well, until I noticed that the game does not always respond to my left and right mouse clicking. I can move around and everything without any delay, but when I'm fighting it just doesn't always work. Sometimes my gun fires, sometimes it doesn't. Can you help me solve that problem?