My sons sky box in his bedroom went a bit mental the other night, had to ring them up and give them some info from the services screen and they corrected it straight away
This happens to us every now and the we do the following:
1 unplug skybox.
2 remove viewing card and wipe with clean cloth
3 plug skybox back in
4 replace viewing card
5 wait 1 minute
6 use remote to turn skybox back on, this can sometimes take several presses of button on remote
7 when skybox eventually turns on, it defaults to channel 998
8 select whichever channel you want or press play to play recorded programme.
Hope this helps