Windows Update hangs and new updates are uninstalled after a restart
<QP>
Consider the following scenario:
- You have a computer that is running...Windows 8.1...or Windows 8.
- You install updates from Windows Update.
- You restart Windows when you are prompted to do this.
In this scenario, you see the following message during the restart process:
Working on updates
13% complete
Don't turn off your computer
This is an expected message. However, the system appears to stop responding (hangs) for about 15 minutes. After this time, the system does restart. However, the updates that you just installed are now uninstalled.
</QP>
Source & more: https://support2.microsoft.com/kb/3064434/