After installing the 8.1 update, the past 2 days, I've noticed that my phone rebooted twice on its own. Sometimes I have to force power it down to reboot because the screen will not come back on. I also notice that when hitting the power button, there's a 5 second delay 50% of the times. Definitely could be a driver issue because they haven't updated the firmware for my Nokia device.. But.. Anyone else experiencing it?