My Windows7/pro set up apparently has automated updates enabled and has been working well till recently.
I get the Yellow "Bang" shield on my Shut Down button in the Start menus that will install updates on shutdown.... except this one 2016 December Security and Quality Rollup for .Net Framework.
At least that's what I think is the hang up as its the only update in the Windows Update selection page. I've unchecked this, clixd OK and hit the Shut down.
The machine will shut down, but the problem is reinstated next session.
Need more info?