I'm sorry to hear that you're having this issue.
Without being able to inspect your unit, unfortunately I'm not able to diagnose the problem. I'll be happy to bump this thread up to see if any DIY'ers can chime in on competitive parts and prices.
My 50' Samsung plasma (about 18mths old) is showing horizontal lines. Looks almost like static. We tried tech support but all they told us was to call for service. We took it to a local repair shop & they say its a "bad circut board" already paid them $50 to look at it & they say its another $450 for repair. It was only an $900 tv... do these charges sound legit? & does it sound like it is the circut board? Afraid to pay for the repairs since I have no warranty! Advise please???