Every once in a while I accidentally press the 7 key on the numeric function keys instead of using the numeric keypad trying to get a top view. This causes all components to disappear, though they are still listed in the Outliner.
theres an emulate num pad option in the key settings which will make your top number row act like a numpad in case the layer switching gets annoying. im not quite sure what will happen if you turn that on and you have a numpad.