Dell Studio XPS 16 multimedia buttons above the keyboard are locked

The pause/play/volume/eject/etc. buttons above the keyboard have stopped working for me.  They all light up normally with the exception of the stop button which either lights is lit up like its constantly being pressed or it won't light up at all.

This happened to me once before a month ago and the problem fixed itself after a week.  Does this sound like a hardware issue or did I do something to lock the buttons without knowing it?