So I got a macbook, about 14-15 months old, never had any problems with it. But one day, outta the blue, my "N" key starts making a really loud clicking/snapping sound whenever I hit it. So far it hasn't been doing anything bad other than that, but it's kinda making me worried that soon it's gonna up and stop working, or spread to other keys or something. Can someone tell me what the cause is, and how I might fix it?