Samsung HCN5527W

I have a Samsung HCN5527W television. I can not see the picture while in Hi-Def. I can hear the sound but no picture. I called Samsung technical support and they tell me its my cables. I call Time Warren cable, because I have an Explorer 3100HD. Time Warren tells me that I need to replace my box and call technical support to coach me through the set up. My hi def was working fine until I had to have my coverage replaced. I had red displaying on the screen. I now can not watch Hi Def channels any more. Is there a set up in the Samsung HCN5527W that I need to make?