Hi, I am frequently experiencing channels being off the air on my TIVO box. The latest one is CBBC (channel number 702) which shows an error message ("There is a problem with the signal for this channel..."). The message also has a "W02" message.
I'm really sorry to hear that you've been experiencing some issues with signal loss to some channels, and I'd really like to look into this further for you.
I've tried to locate your account using your forum credentials, however I failed in my mission, so I'll send you a private message in order to ask some further questions. Please look to the top right of this page where you'll see a purple envelope icon, click on this and you'll see my message.