HDMI Input Issue - Only One Port Working
Well, it seems like you either looked through the forums, or spent a lot of time troubleshooting (or both!). Normally I'd think that "Searching for Signal" or "Not Supported Format" would be a resolution issue, but since you've tried that with no success, I have to admit that I'm stumped by the outcome. HDMI-4 may be an independent input - just a thought, though I'm unable to confirm that of course.
What I would suggest is having the unit serviced. Since it's a B-Series, that indicates a 2009 model, and you're likely under warranty still. I would definitely recommend registering your product online (which gives an additional 3 months of warranty coverage for U.S. customers), and then calling in and seeing if you can have your unit inspected and repaired.
If you'd like to try a home remedy situation, with the TV on, hold down the EXIT button, and you can reset your television to factory defaults. I would note, however, that if you had your television professionally calibrated, those settings will be gone.
Keep me posted.