For those moments when it freezes in the UI menu.
We've all gone through the waiting after selecting a loadout that doesn't work, trying to fly a mission that requires an aircraft we don't have, you know the drill. And the sim hangs for good. Time to reboot...
...not. The trick is to refrain from clicking on absolutely anything until the uimusic stops, the hard drive light calms down, the sim has done its "thinking". If you click on the menu bar it'll somehow deactivate the application and shifts the attention to something running in the background by which time you'll have to try Plan B but I'll get to it later. In the meantime go with Plan A.
Plan A: when everything is quiet and still (and you haven't clicked on anything) hit Alt + F4. Simple as that. It should - read, should - kill CFS3 and throw you back to desktop. Problem solved, fire it up again.
Plan B: if you panicked or Plan A didn't bring results hit Alt + Tab, Alt + F4. Keep doing it until the next program in the line is CFS3 and the hang is released. The downside of this approach is that you'll probably go through several programs which get closed as well but hey, rebooting doesn't give them much chance either.