Uh, okay, so I have a 15inch pb g-four and today my keyboard's four numerical button stopped working...my 3 and 5 work fine, but the four just refuses to work....nothing was spilled on the board or anything...anyone have any suggestions on how I can get it "unstuck?" How much would a new keyboard cost me? I totally don't want to have to cough up for a new one, but this is pretty annoying...