So last night I was just doin some browsing with my charger plugged in, and all of a sudden my MBA just shut off. I turned it on again, and after 5 minutes it just shut off again! I reset PRAM and it hasnt happened again today.. but.. Ive noticed the computer is COMPLETELY SILENT. I can't hear anything under the hood, no fan spin whatsover. anyone have this problem? and how can i diagnose if my fan is actually dead? any help appreciated, thanks.!