Ok this may be a long one I need to put in some detail so this makes
sense.

I am replacing all my receptacles/switches in the house to decora. In
my living room I found through much trial and error that there is a
plug that has a live ground. It's 120V from the ground to the box.
It was isolated or not touching the box when the old receptacle is on
there, but since I have tried to put it on there, it causes a short
and trips the breaker.

I have the cct on right now, but have to pull the wires out of this
one box so the ground doesn't touch anything. The plug to the right
of this one tests fine with my little tester. (kind iwth 3 lights you
plug into receptacles).

The plug to the left is weird. It tests for "open ground" (thus
because I assume I have pulled it's ground off the other box) and it
says Hot-Ground switched. I measure 70V from line to ground wich is
weird. There are 2 cables coming into this box, and I think it must
be 2nd from the end of the cct as there is one last plug behind our
dining room hutch which I won't replace.

Can anyone tell me what could be the problem with this cicuit? I
can't figure it out. I have inspected the cables coming into the
boxes and they seem to be fine. It's been working for the past 15
year as the ground in the one box wasn't touching ground, but I of
course don't want to put it back like that.