My LG RT-23LZ550 TV takes about 10 mins to 'warm up' which means it take 10 mins to get rid of several vertical green stripes and pixelated stripes runnig down it. The only way to get rid of the stripes is to switch channels through my DVD player (swithcing form watching free-view channels to watching DVD mode). Swtiching channels on the TV does nothing and niether does through my Digital TV Set Top Box. It's driving me nuts becasue it seems to be taking longer and longer for the TV to 'warm upl'. It used to take 2 mins and now 10 mins. The TV is only about 4 years old. Why is this?