I just picked up my 3rd MBP in 3 weeks today. The first one had the problem with the yellow tint on the lower 1/3 (it was a Samsung screen). The second one had an LG screen which was perfect, but experienced random shutdowns. The 3rd one seems like it might be the one (no screen issues so far; LG screen). I did notice that when it wakes out of sleep the whirring noise you hear for a couple of seconds is louder than the other two. Is this normal? What causes this noise when it first wakes from sleep? Is it the hard drive?