I started using JRiver because of MadVR and it has been great for Movies - but it has never worked well (at least on my HTPC) for Live TV.
Maybe JRiver should set the default to use something else (EVR?) besides MadVR for TV viewing. It's getting frustrating to have MC lock up so frequently when switching Live TV channels. It works for a while, then the same lockup/freeze. When I switch TV channels the audio keeps playing but the picture freezes. I have to Cntrl-Alt_Del to get to the MadVR "crash window" as it is behind the theater View window. When I get to the MadVR crash window I can choose 1) Restart application, 2)close application, or 3) Continue (and send a bug report). Only selection 1 or 2 does anything. It would be nice if the crash window was on top so I didn't need to get out the keyboard but the real problem is the freezes. I have three HTPC clients. It doesn't matter which one I'm watching - they all freeze up the same way.