Sometimes I just get the opening screen, with the three coloured circles, and it doesn't go to the TV Guide. But it seems to have fixed itself now. Perhaps they were just doing some maintenance during the down-time.
This is a very useful site....
http://www.tvcatchup.com/
I mostly access it via my 7 inch Samsung Tablet, in the middle of the night when I can't get to sleep. It has all the important channels, with only a few of the crappy ones, like the shopping ones. It 100% free and you could actually do away with your telly if you wanted !