This can happen if the TV guide has had trouble updating or if the box is being turned off at the mains every night so what we'll need to do is give it a push to get your TV guide back and up to date.
When you have time go to these options -
Home - Help & Settings - Settings - Network - Connect to the Virgin Media Service Now
You will then see another screen pop up which will go through different stages, you don't need to keep this on your screen so if you press the TV button at the top right of your Virgin remote it will remove everything off the screen and continue to work in the background which can take up to one hour to complete. but please let me know how you get on after the forced connection.