How to fix freezing?

I tried the solution to the freezing problem copied below. But, at the Manual Search stage, the Box just stuck for on: (1) Channel...21. I eventually went back (via Exit) and did an Auto Search. The result now is that every few minutes all the channels I've tested (BBC1, BBC2, BBB News 24, Sky News) momentarily stop every few minutes. This box was a Xmas present. Should it be returned for a replacement?