I just bought this through Steam and running this under Windows 7 (JP) 64bit Laptop. Whenever I play single player, it randomly locks my keyboard. Mouse works but I need to ALT+TAB to return to desktop and then come back to the game to have my ESC or "B" key working. But basically when it's get into this situation it's done. (Happend on gunner, assassin, default character so far. haven't tried other character yet) Check if CAP LOCK or my language front-end isn't running, so it must be a problem with something else. Strangely I haven't experienced this on Multiplayer yet but pretty much happens everytime I play single. Great game but very very annoying. I read that someone had the same issue so thought it a bug.