Mine too has this extremely annoying buzzing and I think it gets worse. I don't think that Microsoft can do anything about it because it seems a hardware issue (I am not a computer engineer though).
I also have a creaking sound whenever I pick up the laptop and some said that this is due to the screws of the body being too tight. I could try to remove the rubber feet but if I destroy them, Micro$oft isn't providing replacements.
If you also think about the reports for the cracked screens and various other problems it doesn't seem that MS put too much time in testing these machines before releasing them and this is unacceptable for a laptop in this price range.