Why does my Recent Apps Buton/Light and Back Button/Light keep flashing

[anousha98]

The 2 light up buttons either side of the home button keep on flashing as if i've pressed them and then close down whatever app is open as if i clicked the back button. It has happened before but it stopped after a couple of days do i left it but now it won't go away. sometimes i will open an app and it instantly flashes and closes the app, other times, it takes 10 to 15 seconds before it flashes.