I experienced on the experimental branch that if you tab out of the game the game crashes and so does the operating system. The PC doesn't shut off but returns to the locked windows screen. I'm running two monitors and the second monitor gets shut down, so maybe it's the graphics card driver that crashed. This only happens maybe 1/10th of the times i try to tab out. It doesn't matter if I'm on a server or in the main menu when tabbing out.