Need help with a DirecTV HD problem

I have the DirecTV in HD but the local channels aren't available without buying this additional antenna. I bought it and received my local hd programming in the beginning. Lately, my NBC and ABC affiliate stations aren't working correctly. I get either no picture or one that freezes up constantly. The CBS and Fox work fine. Is there something I can troubleshoot to "pull in" NBC and ABC again?

Hope that made sense. I'm getting ticked about missing College FB in HD on Sat and the Sunday night NFL game.