Showing the PiP while the PC is connected to HDMI took some obscure config changes on the PC end. The manual is correct, but unclear on what to do. Here's what I did to get it to work. I have posted this as a review on Amazon.com also.
If the TV thinks your HDMI PC is a video source, PIP won't work. So, how do you confirm that it's seeing it as a PC? Name the input PC? Nope. "Scene select" as "Graphics?" Nope (but you should do this). You need to set the PC to send the signal using "PC timing" instead of "Video timing." I'm reasonably technical, but hadn't heard of that. On the video card on my laptop (Intel Graphics 3000) I was unable to see ANYTHING on video timing in the Windows resolution config screens.
Here's how I did it. While my PC was connected to the SONY TV, from the Windows resolution screen, I selected "Advanced Settings"
Then, I went to the hardward specific control panel (this was a tab in Advanced settings). For me, this was labeled "Intel Graphics and Media Conrtrol Panel"
From there, I selected "Advanced application mode" which gave me all sorts of settings.
The important one is "Custom Resolutions" (which is a bit scary, as you get a Warning about causing instability, additional heat and other damage, etc) Yikes!
After overcoming my fears, I created a new custom resoution (which was the SAME as the auto-detected resolution) of 1920X1080, 32 bit, 60P HZ, but the DIFFERENCE was in the dropdown field which read "timing standard."
***IMPORTANT*** This is the thing that you need to change. On page 44 of the manual it says that the needed standard to show a PC in HDMI mode is "CEA-861" and this was the last item in my dropdown list. (not the default selection which was "GTF")
Once I saved this custom resolution with the timing of "CEA-861", everything LOOKED the same, but NOW the TV saw the HDMI PC input as a PC and when I pressed the "Options" button on the remote, the PIP option appeared!
Obviously, this is a video card thing, and not a TV problem, but the "PC timing" thing is so obscure to most people that hopefully, this helps someone.