I've had the same problem today on my box pro and have tried rebooting the box, removing and re-inserting the ethernet cable and restarting the router. Nothing worked. It's strange as all the internet channels are still available and I know there is no issue with my router or my internet connection.
Update: just as I write this, the apps have reappeared, but the guide is still not working, nor are the sections for Whats on TV now, my most watched subscribed channels, recordings & watch list (although I can get to, and watch them, TV shows, Films and Sport. Wait, the guide has started working again!
I guess there seems to have been a temporary issue which, fingers crossed, is slowly correcting itself.
