Thanks for taking good care of Dr. Sanders!

The screen rotation is a "feature" of the graphics card.  Besides the direct key-combo shortcuts, you can adjust the rotation using the Display control panel  ... though you may get a pain in the neck trying to read it.  Actually, I shouldn't be cynical about it: it can be useful if your physical screen is mounted to rotate and you've got a reason to use a portrait view.  But it's certainly unnerving the first time you run into it in a classroom.  (I wonder if it happens by accident or pranking.)