Several times a day when loading a new app from the launcher, the App name will overlay the notifications in the top left of the screen and the rest of the screen will be black. Gestures such as Back and Home don't work. Leaving the phone to lock then unlocking it has no improvement.
Unlocking the phone then dropping down the notification area and clicking on any app's notification opens the app and the phone returns to normal.
Unlocking the phone then dropping down the notification area and clicking on any app's notification opens the app and the phone returns to normal.