External humidity reads NaN after a day or so

 After a day or so my external humidity reads NaN. At the same time the external temperature is frozen. The only solution is to power cycle the board as resetting it does not work. I think I saw another thread on a similar topic implying that it was a power issue. I don't think that's the case here as I have tried a couple different sources and gotten a similar result. This is a bit of a showstopper for me at the moment! I guess I could just power cycle every day or twice a day but that would require additional technology that I really don't want to mess with at the moment.