Hitachi Plasma TV Model PD32-A3000/AVC-A3000. When I turn the TV on (from standby) the screen's

Question

When I turn the TV on (from standby) the screen's green light is on and it goes from black to pale blue but the AVC green light doesn't light up (from standby red light) and there is no picture, but there is sound. This has happened a couple of times before and it has been OK after I have left it turned off for a couple of hours but this time I can't get the picture - even after leaving it powered off overnight. I have checked all cables etc and they are all OK - do you have any idea on why this is happening and how to fix it? I purchased this in August 2003