Is your unit in SHOP Mode, perhaps? Try changing a picture setting (contrast, brightness, etc) and turn the unit off. If you turn it back on and that doesn't stick, then your set is in SHOP Mode. You'll need to reset the TV and set it to HOME Mode.
I've a Samsung and it's a massive 19" - here's the snag. I've a light on the bottom of the monitor that will not stay out. There's an option in the setup to shut it off, but no way will it.
In the Setup, the option to shut it off completely in the "Light Effect" - but no matter which way I take, it doesn't save. I can "exit" or "enter" or it the "back" button but it doesn't save. The light will go out but in a few moments, back it comes on again.
Any idea as to how to overcome this?