Yup, same problem here with a LN40B TV. It has already had the boards replaced TWICE and it happened again early this week.
I have the following boxes connected:
- HDMI2 Sky TV
- HDMI3 PS3
- SCART - Wii
No matter what HDMI channel I select, I can only see the PS3's signal. I have to switch HDMI leads around to watch the Sky TV.
One thing I have noticed is that every time the fault has occurred after playing on the Wii for a while.
I'm going to try the 'power down and remove all the plugs' technique.
Since this kind of issue has been going on for a couple of years now, you'd think Samsung would've fixed it or at least acknowledge it as an issue. Everytime I contact them they send an engineer out.