SHARP,PIERCING, ALARM LIKE NOISE COMING FROM TV

I had the exact same problem with an Olevia 542I purchased in Dec 2006 . . . a loud (top volume) "fire alarm" noise from the TV when you least expect it that would only stop by cycling the power. It practically knocked me out of bed. The cat's were freaking out! Olevia replaced the TV when it was five months old. Now the sound has gone out on the replacement (which was a refurb unit) after less than a year. The RCA outs still seem to work. Olevia refuses to do anything even now though the TV is clearly a lemon. I've found numerous other postings about Olevia sound issues such as these. I won't buy another Olevia!!!!!!!!!!!!!!!!!!!!!!