ok. there are three possibilities.

3 . electricity being sucked on another home appliance. (happened to my friend.)
ok, as we know, appliance such as refrigerators suck a huge amount of our power. sometimes, it goes to 'sleep' mode because the temperature inside it is already cold. once needed, the machine will auto kick back to suck up the electricity (listen to its humming sound) my friend had the same problem, so I went to his house to check what happened. i noticed once the thing sucks the electricity, the ps3's display will be affected (the lcd turns blank but game or video stays normal) no other choice, either you move house OR dedicate a plug (usually PS3 on power sharing with other appliance is affected )  solely for PS3. i referred this case to one of my colleagues here and he said its actually a good thing, means the ps3 is well aware of the surge thus its adjusting itself to the new electricity priority, hence the intermittent lost of display.