Inventory not accessible/ cannot change item in hand

DEVICE: Nook HD+

GAME MODE : Creative and survival

VERSION : 0.7.1

ISSUE : After approximately 10 minutes of gameplay., selection of inventory items has frozen. Cannot change the item in hand. Other areas of the screen are also non accessible (repeated screen tapping generates no response)...though the player is able to walk and move around the world.
I am only able to resume the game after shutting the Nook HD and reopening the game.