ipad 2 random update screen after ios 8.3

After updating my ipad2 on ios 8.3, it shows a white screen when I turn it on, and says "slide to upgrade".

But then It does again, with a white screen and the apple logo loading. this happens all the time while using apps or when it is in home screen.

Sometimes it may work fine for 5 or 10 minutes and then it starts again!!