Re: interior home problem
Sounds like expansion and contraction of the structure, a normal happenstance during seasonal climate and humidity changes. This expansion and contraction works drywall nails loose, then as the drywall slips on the fasteners you hear squeaks and knocks.
The cure would be to run a screw 2" away from all the nail pops you see, which will draw the sheetrock tight to the framing. Tap each nail with a hammer to reset them, then you'll have to fill all the new fastener and hammer marks. If seams have become exposed, retape those as necessary. Float the entire surface smooth, then retexture and repaint.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!