I was having some problems installing Windows 8 KB2770917 update, it stopped at 15% and then it rolled back the installation. As being diagnosed as having CUD (Cumpulsory update disorder) I found a solution in Microsoft site:
Run msconfig (Windows+R, msconfig)
Go to Services
Select Hide all Microsoft services
Disable All non Microsoft services
run msconfig again, Services and Enable all Services
reboot again to start the services
and it worked for me.