[mythtv-users] How are channels determined?

[PAUL WILLIAMSON]

Does Zap2It send down the information about what frequency 
the tuner card (a PVR-250 in my case) should tune a particular 
channel to?  Specifically, I had things working great on stable 
.16 for a few days, and now for some reason all channels are 
fuzzy, and some are just wrong.  

For example, I can tune to channel 2 (NBC in my case) and it 
works, sound is ok, but picture is fuzzy.  When I tune to channel 
3 (pbs) I still get channel 2, but a whole lot fuzzier.  I also get the 
sound just as if I was on channel 2.  Just about 
every channel is either a little fuzzy or totally unviewable.  I have 
plenty of signal, as I connected the PVR-250 directly to the 
incoming feed with the exact same results.  The picture on 
every TV connected straight to cable works fine.

Do I need to edit my channels manually?  I looked through the 
archives, but didn't see any subjects that fit what I'm seeing.

Thanks,
Paul