Steam thinks error "Failed to start game (App already running)

Every time I try to start the game, it gets to the pre-launch installs and then stops working. I already sent in a steam ticket, but maybe you guys can help me faster.

Oh, and I tried all the steam recommended stuff (Turning off the compatiblitys, uninstalling steam, ect) and some stuff from around the internet that helped simular problems. But nothing seems to work.