Where would I be getting the noise from? The plasma's breaker is still shut off.
If you have a battery operated portable radio, just tune it to any am or fm frequency and scan / sniff the area with the antenna
and if you hear a lot of static you are finding noise sources. See if that noise is present at the computer, BOB, Keyboard, etc.
You may be creating a very large electrical field just by turning on /off the plasma breaker and causing an electircal field to be set
up around a recieving source and over time it can dimish ....thus things seem to work....proper shielding and grounding comes into play.
Noise sources or interference can be a cross to find. A large field source can screw up a computer and cause it to do weird things.
I am not saying that noise is your only issue.
Keep it simple and just do one axis at a time. Go through the process of elimination as suggested.
FWIW,
RICH