This happens when the phone OS was updated to review new features such as 'Cortana'. The screen when you click the on button cannot be swiped up, but some of the other functions function as expected. There should be a fall back for such an eventuality. :smile:
Hodentek Mobile: Think before you update to Windows Phone 8.1 Developer Preview on Nokia Lumia Icon
Hodentek Mobile: Think before you update to Windows Phone 8.1 Developer Preview on Nokia Lumia Icon