Why does the freeview digi boxes always crash?

Pixelisation is caused by a weak signal being transmitted by the TV companies. ITV,C4 and Five are particulary bad. In essence the less power used to transmit is cheaper for the company so they keep it turned down as much as possible. However in certain weather conditions this can prove Too much, and you get the picture breaking up and "Popping" in the speakers. Alternatively the weak signal may be caused by your Aerial. Have you had it checked? If it is old this could be the problem just as easy. I presume you have checked your postcode on the Digital website to make sure you are getting full digital coverage.