By default, Windows8 does a hibernate shutdown to speed up booting. Eventually you may have issues where this doesn’t work. You can boot into Safe mode and delete the hibernate.sys file from the c: directory, or you can disable fast booting. I elected to disable fast boot since I use an SSD drive and boot up quickly anyway. To disable fast boot open your power option via the control panel or Win+x menu. Expand the advanced option are and uncheck the fast boot option.
Shutdown should now work again.