After my laptop locked at 5 min screen saver, I tried to login, but Ctrl+Alt+Del is not responding to my keyboard. I tried plugging in the USB cable to a different port, but still no response. The strange thing is that if I hit the "Switch User" button, I am prompted to hit ctrl+Alt+Del again, and it works. Then I tried logging in as a different domain account and can do so successfully. So I logged out and tried logging into my "Currently Logged In" account, and it prompts me for ctrl+alt+del again, which does not respond. I then tried hitting "Switch User" again, and the hit the red power button and chose "Shut Down", and now the screen is hung. I'll try powering off with a hard reset, but it is a bug as far as I can tell. Maybe a bug with the screen saver?