Whenever I wake my computer from sleep, there is a crackling sound that comes from the hard drive. After that, every five minutes or so, the crackling sound continues. It's like the sound of some crinkling a plastic sheet/static-y sound. I can hear the hard drive whirring and the crackling sound coming from that. Is this normal? I have a 2.4 ghz Macbook aluminum, bought in Oct 2008. I'm hesitant to bring it in right now because I have finals coming up in 2 weeks and I need my laptop for it. I've already brought my Macbook in and had it sent in two times due to issues w/ the keyboard (keys not working or falling off), and each time it took about a week to get it back.