So Whenever I am just normally using my device , suddenly when I pull down the notification panel , the screen would freeze .Like touch won't work. ,Untill I press the power button to off the screen once and then unlock the phone again to make it back to normal .Same happens when Suddenly I'm typing some messages in WhatsApp .It happens so frequently that it's very irritating. Please fix it asap .I attached the screenshot of the screens where it occured mostly .