Just got my MacBook Pro! 15.4" with 2.4Ghz Proccessor. A few questions.. Does anyones return key feel spongy and unresponsive when pressing it? Mine does.. How do I find out which model of screen mine has, and which is the 'bad' one? My screen also noticeably dims when I rub my hand down the left speaker, why?! And how do I tell if my screen isn't yellow on the bottom half? Thanks!