loss of block of channels ie 7/ 70/ 71./ 72/ 73/ 74/ 78 repeated attempts at manual dtv tuning and auto tuning failed to fix but corrected itself 8 hours later ....1st time this has happened 2 years ago with channel 9 block two weeks ago channel 7 block of channels and again last night what causes bad pixilation and loss of channel nieghbour across street had good signal and reception