Have just bought a new tv with freeview. This replaced another tv with separate freeview box with a perfect reception. The new tv gives good reception for some of the time but other times the picture is 'blocky'. (this is the second new tv I have tried with the same problem, if I put my old freeview box on the new tv it still doesn't work!). Can anyone tell me if this is an aerial problem, if so any ideas how much would it be for a new aerial.