My computer last night started to buzz kind of like a prop plane taking off. It varies in intensity from barely audiable to being able to hear it across the room and only stops when I turn the computer off. It seems to get quieter if I lay the screen flat, I can only hear it if I put my head near the screen. This morning when I turned it on, it was not making noise but by the time I returned from breakfast it had. I took the hard drive out and dusted it, but other than that I'm clueless as to what to do. Is it the fan, a scratch in the harddrive, or what? Should I try to find someplace to take it to? Please help!