I had an issue with digital dropout and the last time that occurred I simply removed the cables, sprayed them with contact spray, and that solved the issue.
That issue returned though on a different channel. Again, I used contact spray and the issue was solved, however the Guide feature had vanished. When I would click on Guide, I would receive a message that it was unavailable and for me to check my Aerial setting ... or something to that effect.
I tried resetting, a hard reset, and that had no effect other than wasting my time.
Eventually I went to Menu \ Broadcasting \ Aerial and I saw Cable was selected (as it should be). I changed the setting to Satellite and was prompted further regarding Time (or Clock), Auto or Manual. I chose Auto and exited the Menu.
I now had no channels and so I went back and selected Cable, the correct setting for my situation.
That did the trick. I'll assume since Guide is Clock \ Time dependant that reselecting Auto for Clock or Time solved the issue though in order to access Time or Clock I first had to change the input from Cable to Satellite (and back again)..
At any rate, this worked for me, maybe this will work for others.