Hi, I bought a 42' Hitachi plasma at xmas and upto about a week ago it has been fantastic - no problems at all, however recently it has developed a strange fault. Whenever there is bright white on screen (either on and advert of tv show) it REALLY buzzes. If I put the all white screen saver up it also really buzzes but then after a while it stops. Is it broken - do I need to contact Hitachi? Please help - any advice greatly appreciated.