hifiman5
If you're uncertain how to do this work safely, it's best to hire an electrician.
The solution was opening up the breaker box and tightening down ALL of the ground wires for each circuit. Some of the ground wire screws had barely been tightened at all. You MUST be careful doing this and you should turn off the main breaker before proceeding ...Excellent advice. I would add only that the electrical connections throughout the house should be similarly tight, including the hot and neutral connections not only in the service panels, but in every electrical box and on every device connected within the boxes. If terminations to your devices use the push-in connectors, they should be disconnected and firmly attached to screw-on terminals instead. A compromised connection anywhere can send noise throughout.
If you're uncertain how to do this work safely, it's best to hire an electrician.