I have a Toshiba Satellite Pro L850 laptop and have recently(a month or so) been hearing some quiet very high pitched(edge of my hearing) whirrs, hisses and other such sounds from the right hand corner of the laptop(take a straight line from the "power on" indicator light toward the power button and a straight line from the two USB ports toward the left and where they intersect is the approximate noise source.). now this noise might have been going on for longer, or it might be something from the last few months only. it could have been happening earlier but i never noticed, i can't be sure. furthermore if i put my ear right up against this spot i have described i can always hear a faint buzz and hum, i have naturally only put my ear their since i started hearing the slightly louder noise from that part of the machine. the louder buzz,hum,hiss,whirr is only audible a few times every hour. what part of the computer is making a buzzing noise(hard drive, usb ports, some sort of power system)? is it normal for this type of laptop?should i be worried? can anyone provide a diagram of the internal arrangement of this specific laptop type?