I'm not an electrician by any means but I don't know that I recall ever seeing nor hearing about the neutral (white) and the ground wires being terminated on the same screw. I agree with Mike, I'd certainly be getting a licensed electrician to look at your wiring.
Also, if you are hearing a very faint pink noise I don't know that I'd tear myself ragged trying to locate the source. I had a ground loop problem whenever I placed everything in the new room and still had the slightest of a faint noise from the 80s even after the ground issue was taken care of, such a faint noise that I had to put my ears right up against the speaker to hear it but now I don't even bother trying to locate the source because the noise is that faint ... matter of fact I don't even know if the noise is still there or not, maybe I ought to go see.
