It is most strange in the way that the red stand-by light is acting.
So, just to confirm what procedure you go through when switching off, - you don't un-plug at the mains, you just press the bottom right button on the remote, the 'curtains' on the tv close and a red light appears in the bottom right corner of the tv screen. If you did not turn your tv on for say 2 weeks, would the red light in the bottom right corner just stay on continuoulsy 24/7.
Then, when you come to wanting to turn the tv on, you press the DTV button on your remote?
Do you ever un-plug at mains?