Spotted the same problem here over the weekend too (although now I think about it I may have noticed it Thursday whilst flicking through channels but it didn't register...).
I'm seeing the symptoms described here on...
6 ITV2
14 Film4
15 Channel 4+1
18 More 4
26 ITV4
28 ITVBe
30 E4+1
35 ITV1 +1
Going to log it with Humax support now - I know they are already on it from what I've read in this thread but I guess the more that register it the more hope of a speedier resolution there may be.
TMW