Whenever my screen is not turned up to the maximum brightness, a really high pitched sound is emitted from the laptop. If you've ever heard the "mosquito ringtone", that's basically what it sounds like. Really odd. It's definitely got something to do with the screen brightness, and I basically can't use my laptop at medium brightness because the sound drives me a little nuts. Turning the brightness to the lowest setting makes the sound less intense, but it's still audible. Is there any way to fix this? Also, would this problem be grounds for a replacement? Thanks.