Most likely the black screen with HD channels has someting to do with your codec settings. I had the same problem while using FFDShow. Since that I am using the Cyberlink PowerDVD codec I can watch HD channels without any problem.
You can try Cyberlink PowerDVD for free (30-day trial), http://www.cyberlink.com/
You can try Cyberlink PowerDVD for free (30-day trial), http://www.cyberlink.com/