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