I have a HP 6vt and once I put cheese in full screen it has no way to move back to a window since nothing on my computer works at that point except the off button.I even went to software center and un-installed cheese and then re-installed it and as soon as I open cheese it goes to fullscreen and nothing will close it except restarting the computer. I have tried the F11 button and alt cheese but nothing works once the computer starts cheese.
F11 should work as it is the key putting it in fullscreen in the first place.
To kill cheese you should be able to log into another tty session using for example ControlAltF5. Once logged in, type:
Then go back to your graphical session with ControlAltF7.
I would also suggest: