I'm very sorry for any inconvenience this may have caused you. Unfortunately, this sounds like it may need servicing. Here’s the thread where you can get details on setting that up: http://forums.cnet.com/7723-13973_102-542437/service-issues-click-here-for-help/
My picture in picture was functional for a little while then i started messing with the settings(i think it was when i activated the Plug&Play) it grayed out the pnp.
the model is UN55B7100WF
I've tried updating the software and that did nothing i tried looking for a factory reset but nothing shows up and I've red about it possibly being an analog only option and I'm not sure what that means but I'm using two devices that use HDMI