That was what actually happened to my PC the other day.
In the end, I just force-closed the damn thing and restarted the PC. That got me nowhere, except onto the maddening merry-go-round again!
Although I am no tech-savvy person, I am sufficiently familiar with PC madness to know that however unique a problem you thought you are having when the PC acts up, many others would have experienced the same problem you are now encountering.
So I got my android and searched the net for a possible solution.
And sure enough, there are tons of discussions out there.
Some say to take out the battery and place it back again, blah, blah, blah. But if your device is not battery powered, that is completely blah, blah, blah to you!
One even suggested that you get to change computer settings, which was just dense or idiotic when your PC is caught in an eternal loop! If you could get to settings in the first place, then there wouldn't be a problem, would there?
Others suggest you try to restart in safe mode by pressing F8 button, etc, etc, etc, blah, blah, blah. But the F8 key for most machines nowadays won't do the magic of getting you to where you are supposed to be getting to the safe mode option.
But I knew enough not to give up so I persisted with the search until I got to one site where someone suggested to press the Windows key and the D button blah, blah, blah.
I ignored the 'blah, blah, blah' and just pressed the Windows key and the D button and bingo! I was brought to the sign in to the PC page!
Then I disabled 'automatic updates' and opted for the 'Check for updates but let me decide..' thing.
Now everything is to back to sweetness until the next time the PC decides to pout and misbehave again as any machine is predisposed to do now and then, I guess. But I sure would like to thank the genius who suggested the simple solution.
I don't know whether it will work for you (just as it for did for me) or not, or whether it will just aggravate your problem, but if you are in Windows 8.1 and facing the same bug, you could give it a shot.