That does sound sort of odd -- maybe you typed it into a Windows command prompt by mistake (not sure if Windows even supports a shutdown command)? In any case, you do need to be the superuser ...
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What to do if your PC won’t shutdown properly
If your computer won’t shutdown properly, it can be very annoying. There could be a range of possible causes for that. But one cause could be if it’s hanging up in hibernation mode. To shutdown ...
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