Your installdr links are stale and I meant to mail you about that.. Take out the /InstallDoctor/

Crap. They changed the links AGAIN?

For a ground loop to exist, something has to be multiply or poorly grounded, yes?

Not necessarily. When you start talking about complex systems with multiple DC powered devices, you can get some very interesting cases of ground loops without necessarily needing a poor ground in the mix to make it happen.

It's all about potential to ground, and doesn't necessarily mean a bad ground.

Something as simple as having a different-gauge wire for the power feed and the ground line can cause it.