Tv picture will go blank (black) no picture unexpectedly but still have sound and Tv will stay on, no error codes, no blinking lights, no error codes, reacts to remote as usual - vol up/down, channel change, A/V source change. Can stay on for an hour or maybe 2, other times it may be 30 mins or maybe just 2 mins, irregular times from cold/hot start. Picture perfect when it does work - not black and white or spotty or distorted picture. The lamp will stay on, the fan (there is only 1 fan) will stay spinning with no grinding or unusual noises, the colour wheel remains spinning with a slight whirring as it spins down when powering unit off by remote control or front panel. Tried different input sources - Wii console, Sky box (not HD or Plus), Freeview box, standard DVD player and with no input source at all but still the picture goes off. Cleaned out some dust build up from cooling fan/ducting and ballast. Tried to bypass the 5v prot. ctt on the lamp ballast but still the picture goes off. Tried bypassing the thermal sensor but still the picture goes off. Tried removing all IR sources and covering IR sensor on Tv to eliminate other signals but still the picture goes off. Reluctant to replace lamp as it remains on so can't see it being at fault and the ballast lights the lamp and the lamp remains on with either the prot. cct bypassed or not so can't see it being the lamp ballast either. Tried running Tv with rear panel on and off but still the picture goes off, thought this might reduce heat build up on other components which might shut down due to over heating issues but still the picture goes off. When the screen goes blank the Menu does not show up on the screen, for info if this helps diagnose. Help would be greatly appreciated!