If you experience update problems then try to restart your machine - but do it completely!
As Windows 8 started to have two methods of restarting (one fast restart and a whole complete one as in Windows 7) you may not have success in just restarting your machine through the GUI. For that you should use the command below.
Hit Win+R to open the "run command" action and type in the command. You should close all applications before as the restart is executed immediately!
shutdown -g -t 00