Screen goes dark with searching in bottom corner

I have 4 set top boxes in my house and recently have been having issues with the one in my bedrooms.  The screen goes dark and in the bottom right hand corner it says searching.  I have unplugged the router, unplugged all the tvs and replugged them in and after a few hours it starts doing it again.  Sometimes it will be dark for up to 5 minutes and then it will start playing again.