[mythtv-users] channel numbering is messed up: BBC ONE was 1, is now 4173

[UB40D]

I am running mythbuntu 10.10 with a DVB-T-only Hauppauge dual tuner.

Recently, possibly following a rescan/retune after digital switchover,
the mapping between the channels and their numbers has been messed up.
For example: BBC ONE used to be 1, but now it's both 1 and 4173, and
actually the "1" instance doesn't work.

More specifically:

 Frontend / Manage recordings / Schedule recordings / Search lists / Channels

gives me a listing that starts with an ok-looking

1 BBC ONE
2 BBC TWO
3 ITV1
[...etc, but continues with...]
4173 BBC ONE
4287 BBC TWO
4288 BBC THREE
[...]

The more serious problem is that selecting "1 BBC ONE" gives me "No
listings found for this program"! I do however get the expected
listings if I scroll all the way down to "4173 BBC ONE" and select
that.

How can I fix things so that I get rid of the duplicates and put back
the channels where they belong? A new full rescan has not solved it.

Thanks