Then I am not clear on why you said you were having trouble with an update...
Anyways, There are several 'fixes' for this on the net:
- Close the lid and let it go to sleep in this state. ie - dont shutdown or anything. After a few minutes open the lid again.
- Try shutting down, not sleep or hibernate, disconnect the network cable, and power back up.
- run task manager by pressing ctrl+alt+del. Then click on more details and then go in to users menu. Drop down the user name option what ever u have and then select desktop window manger and click end task then a window appears.check a box Abandon unsaved data and shut down. now again click on desktop window manager and click disconnect at last restart ur pc from welcome page.
Let us know if any of those works for you because the other solutions are to restore to a previous date, run system repair; both of which require the win8 dvd which you may not have, or to do a complete factory restore.