Often (but not always) in electronic equipment, the gound is used as a referenced 0 point for the rectified DC, especially when the power supply is creating a +/- DC supply.
You seem to be confusing the equipment internal or chassis ground with the power line ground. One has nothing to do with the other, other than possibly causing ground loops. If the chassis grounds are interconnected and AC current is caused to flow through the line cord grounds and back around through the chassis grounds that can cause problems.
Exactly what sort of problem is the owner talking about with his electronic equipment?
-Hal
