What you describe is a grounding loop issue.
Don't get too tied up in the technical aspects in these articles. Read them to be sure they describe what you are seeing then search around a bit to see if there is an easy solution to your specific situation.
http://www.elect-spec.com/faqgrdl.htm
http://www.epanorama.net/documents/g...isolation.html
__________________
"The problem with any ideology is that it gives the answer before you look at the evidence."
—Bill Clinton
"The greatest obstacle to discovery is not ignorance--it is the illusion of knowledge."
—Daniel J. Boorstin, historian, former Librarian of Congress
"But the Senator, while insisting he was not intoxicated, could not explain his nudity"
—WKRP in Cincinatti
|