I am new to this forum. My macbook pro has been great for 6 months, bought it refurbed. Just recently, a hum started, I think that is just the fan. It seems to want to keep running, though it does not seem too hot. But the really weird thing when i hit volume up or down or turn on music the speakers whine and make mysterious noises quietly. Like extraterrestrial alien noises from out of this universe, if I mute, it doesn't really go away. But playing with the volume up and down, changes the sounds. sounds like a dying lamb or something. I am a bit worried, although not too too loud, definitely audible and worrisome. All, or any advice/tips are appreciated.