I seem to be having this happen often, too.
This last time, I went to the Setup menu, and forced a connection... I don't remember the option name... but its in there someplace.
Another time, when that didn't correct it, I called support. I was QUITE surprised that I got a support person, IN PERSON, within 1 minute. They walked me through some "Zone" functions that cleared the guide, then reconnected. They did that twice. Again... I don't remember the exact zone number or options on the zone menu.
Call them... they were VERY helpful and immediate.
I'm still not quite sure why its happened to me twice now... but so far its been easily correctable.