No idea, they run through the wall somewhere and I've been unable to locate their destination anywhere in the crawlspace or attic.
I can't help thinking they are part (maybe even all) of the problem.
To save me going back through the entire thread -- where is the main electrical panel grounded to? Does it ground to a water pipe, to a well, or to a pair of grounding electrodes (big metal stakes) driven into the ground and buried?
Story: My house was built in 1950. I know this exactly because my parents had the house built. This was the boonies in 1950. I have a well, and when the house was built the electrical system was grounded to the steel well casing through a connection to the pipe leading from the well to the pump, which is located in the basement.
Along the way, at some point while my parents were still alive the pipes from the well to the house failed and were replaced with plastic. But nobody thought to do anything about adding a ground to replace what was now a broken connection. The grounding conductor from the fuse panel (which was later replaced with a more modern breaker panel) leads from the panel in the garage to the basement, where it's clamped to a length of 3/4" copper pipe that comes through the wall from outside, about 4 feet down from grade level. The problem is, that 3/4" copper pipe hasn't been connected to anything for about forty years.
I finally figured all this out when I signed up for DirecTV about fifteen years ago. I knew where the dish was going to mount so I prewired the interior of the house to that location because I wanted to avoid having a bunch of wires running around the outside of my house. When the installers arrived, the first thing they wanted to do was run a ground wire from the dish location half way around the house to where the electrical service comes in. They said this was required by the NEC (National Electrical Code). I wasn't convinced, so I sent them away until I could do my homework.
It turned out they were right, but they were wrong. When I got back to work (which, at the time, was in a town building inspection department), I talked to my boss. He knew the guy at the NFPA (National Fire Protection Association) who writes the NEC Handbook, so he called him. And that guy didn't know the answer -- he had to research it and call us back. It took him a day or two. When he called back, he had a code section to point to. Satellite dishes do require grounding. BUT -- the ground wire isn't supposed to be more than 'X' feet long (I don't remember what 'X' is, but it's about a quarter of how far the satellite guys wanted to run their wire), and it's supposed to be straight, or nearly straight (they were going to make at least four right-angle bends). So I decided to do it right, since I knew the satellite guys weren't going to. I bought a new ground rod and drove it into the ground right below where the dish was going to go, and I ran a #6 wire from the ground rod up to the dish location.
BUT -- and this is where I think your problem may lie -- the NEC allows for supplemental grounds such as what I installed, BUT it requires that any supplemental ground be "bonded" (connected) to the primary building ground (the NEC calls it the "primary grounding electrode system"). So I had to find where my electrical panel grounded, and connect to that. And that's when I discovered that the panel was grounded to a copper pipe that didn't go anywhere. So I started over from scratch. Back to Lowe's, bought two more ground rods and a long length of #6 wire. I drove the two new ground rods in the front of the house, near the well and near the electrical panel. Then I ran a new grounding #6 conductor from the panel to the first new ground rod, and then from that to the second new grounding rod. And then I ran another #6 wire from the supplemental ground rod in the back of the house through the basement and connected it to the new ground rods in the front. That's the "bonding" jumper.
What that does is to ensure that everything is at the same electrical potential, which is what's necessary to prevent stray currents such as what you're encountering. This is why I'm interested in where those "new" add-on grounding wires go, because I suspect they aren't bonded to the building's primary grounding electrode system. And that is important.
Side story -- when DirecTV came back, it was a different crew. These guys spoke English, and they actually seemed to know what they were doing. My call was mid-afternoon on a Friday, and when they showed up they were thinking they weren't going to get home (in the next state!) until very late. When they saw that the house was already wired, and the grounding conductor was right there waiting for them so all they had to do was mount and aim the dish and plug in the tuning boxes, they were ecstatic. They said it was the easiest installation they had ever done, and the only one they had ever seen that actually met the NEC.