Intermittent Black screen

Problem started a few months ago after a software update.  Does it live and on dvr recordings.  Only happens  on my local PBS station.  All the other stations  work.  One station only, .when it happens,  I can switch to a different channel and it works, switch  back and it's still black screen.  Outage last anywhere from 10 seconds  to 3-5 minutes.   Happens on my remote receiver in the bedroom  too.  HR54/700 and a C41W-500.  Current  software version is 0x1b17