Sorry but as I'm not there with a full samsung repair manual, parts I think I'd try these things.
1. Taking a cue from http://www.tomsguide.com/forum/56157-4-turning-connected-hdmi I'd disable HDMI CEC as well as Samsung's SMART HUB for another test run.
2. Try a full factory reset. Mind you that Samsung does seem to have a reset noted in the product manual and another one only they can do remotely. (Come on Samsung, publish how to do that remote reset!)
Bob
Ive seen some similar issues on these forums, though none that describe the actual symptoms. My 50" LED TV that I've had for only a year and a half now, which has barely been used as I was deployed for almost an entire year, started to randomly power off when watching something through the HDMI inputs. When the TV would shut off,I began to unplug everything. From this, I concluded that it all stemmed back to the two HDMI inputs. It just seems that when something is connected to either of these, the TV basically powers off, but comes right back on when the HDMIs are disconnected. It did not matter if it was my Apple TV, Macbook, or Xbox.
Now, however, the TV will not stay on if something is connected into either of my two HDMI inputs, which basically renders this TV obsolete.
Is this a known issue? Is there some kind of firmware update or driver update available so this no longer happens?

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