I'm using a Sky box without a card, and was until recently receiving BBC1 
and HTV West without any problems, however when I went to use it yesterday 
on both BBC1 and ITV I received the message 'This Channel Is Unavailable'.
I then removed the mains lead for a few seconds and after reinserting it was 
rewarded with BBC1 London and ITV Central W, I had this problem once before 
and after doing a hard reset - applying mains power whilst pressing backup - 
managed to restore the local channels.. however on this occasion I was still 
left with London and Central W.. any clues anyone please?