Scroll lock
I looked to my keyboard today and there was another LED turned on... I kept asking myself what that mean??? I have computers since 1994 and never payed attention to this "down arrow" thing... I found out it used to be very helpful (ok.. maybe it still is..)
From Wiki: The Scroll Lock key is a remnant from the original IBM PC keyboard. In the original design, Scroll Lock was intended to modify the behavior of the arrow keys. When the scroll lock mode was on, the arrow keys would scroll the contents of a text window instead of moving the cursor.
Mine is turned on... still... no idea why =D
From Wiki: The Scroll Lock key is a remnant from the original IBM PC keyboard. In the original design, Scroll Lock was intended to modify the behavior of the arrow keys. When the scroll lock mode was on, the arrow keys would scroll the contents of a text window instead of moving the cursor.
Mine is turned on... still... no idea why =D