Keyboard help please

This is a long shot but I'll try. I have an older Microsoft keyboard the
model is Microsoft Internet Keyboard Pro. I do not have the documentation.
Over the traditional Print Screen, Scroll Lock, and Pause buttons are 3
lights. The 1st is for the num lock, the 2nd is for the caps lock, the 3rd
is unknown to me. The light is lit and the corresponding icon is a down
arrow with a line under it. Does anyone know it's usage and how to turn it
on/off? I assume it is the reason why in Excel when I push one of the
dedicated arrow keys (not on the num pad) the highlighted cell does not move
in the direction of the arrow, rather it will work the up/down and
right/left scroll bar. The arrows appear to work okay with other programs.
I really like this keyboard but need to get it out of this mode.

Any help you can give would be appreciated.

Fred

Keyboard help please