I haven't had that problem on my Digihomes (2), so it obviously is something you need to investigate.
I would re-scan before anything else... and maybe think of some key words to put into a search on this forum, see if anyone else has had the same problem.
Are you viewing the EPG from a 'good' station, like BBC1? That may make a difference, there were recently issues with More4, Film4 on some Muxes (that's a rather vague memory, it was definitely to do with Channel 4's output somehow).
Are you in a good reception area?
Sorry not to be any real help.
parthena