it sounds like its the inverter (changes the power so it can brighten up the screen) on its way out.... you can get them replaced, but normally cost a pritty penny.......plus labour charges on top, unless your willing to do it yourself? probably looking at £150 - £200 notes to get it fixed....... as long as it is the inverter, could also be the screen itself which i wouldnt then bother tryign to replace.....