hoping someone can help me. i have sky + now i'm having trouble viewing channel 4. the picture is popping on and off and also the sound at the same time. ihave re-booted but still no look, trying to avoid a call out fee. rang sky asking what could be the problem but the said it was a signal interfering with sky. only had troubles the past few months and i haven't changed anything in the room to alter signal. can anyone help please.