My phone every so often makes this weird sound(notification).Then the screen comes on, goes black with a tiny x on the bottom left of the screen. It stays this way for about 3 seconds and then goes back to the lock screen. Sometimes it will bring up the Samsung VR and want me to stay out. I never have used it. I can go to settings and force stop it but it starts back on its own. Just can't figure out what is causing it. Any ideas?