I have the same problem on my KD-48A9 even on the latest firmware - if I watch a recording on my Panasonic recorder and turn the recorded off and then use the TV as normal most times when I turn the TV off it will come back on a few seconds later. If I hold the power button down and chose restart it will restart and the fault is gone until the next time.
Sony blame the Panasonic player - however if that were the case a TV restart would not fix it. Then they tell me to deactivate CEC - but that's a feature I want to use.
No USB devices are connected to the TV
