The warranty resolution is not what I am looking for.
What I need is the possible causes. I plugged in my personal 7D, that I have worked with for months, and the same thing happened.
I guess I really don't need the obvious answers..viruses..malware...these PC's are clean. Not attached to the internet. Behind lock and key and run completely autonomous.
Is it possible that there is a "geotagging" function in these cameras, that is causing this due to the northern latitude?
That is probably ridiculous, but I'm running out of ideas!
If it's happening to every 7D you're plugging in, then I think it's safe to say that the problem is not with the camera. Instead, it is either the computer, the OS, or quite possibly, some bum cable. How long is the cable? How is it rigged? Did someone put a staple into the cable itself? A kink/bend/snag? Too long, thus loss of signal? Bad CF card? Broken pin in the CF card? If the card is accessible, check to see if you can read/write to it with a card-reader.
The chances of all 4 7D cameras to crap out with the same err 70 code (and for the camera to be blamed) is near a statistical impossibility. Therefore, it must be the connecting hardware, the CF card(s), or the computer/OS.
That's my worthless $0.02.