I opened a chip binder and rested it on the edge of my keyboard. When I finished and looked back at the PC screen, everything was inverted. I didn't even know this was possible!

In case you want to see how it looks, press Cntrl-ALT-downarrow. If you have hot keys enabled (that must be the default) you will have an inverted screen. Cntrl-ALT-uparrow will put things right again.

Mouse directions are reversed as well, so it's difficult to mouse to the help function to see what's wrong. I ended up turning my monitor upside-down till I figured out the fix [g].