Sylvania 6842-PEM 42 in. EDTV-Ready Plasma Television "horizontal flick lines" Questions

...horizontal lines mixed with some static although sometimes this is accompanied by a pulsing strobe effect. It's almost like some kind of interference but it happens on all inputs from different ...

...horizontal line. The intervals between flick/blink are a few seconds to a minute. After about 10 minute the problem stops. I have had the tv on for over 7 hours after the problem stops with no ...