Wow, hard to tell....seems others having install issues with this on the web.....not necessarily Avast.
However, here is what happened tonight for me.....have five home PCs....all W7 64bit, latest everything,
KB3011780 pops up on them.
So on one PC I still have Avast 9.0.2021 I hit install on the KB...it installed and asked for reboot.....which I then got the "Do Not Turn Off PC Windows is Configuring"........sat there for an hour !!!!!!! So......I did HARD reset with power button and reboot....asked me for boot options and I chose Normal Startup.....Windows Logo and then message on registry updates happening.....took five minutes.....then to login screen.....which had black screen prior for 2-3 minutes....and after login took 3-5 minutes to settle.......all this on a very fast machine. Did a reboot and all seems OK...Avast 9 stable....all programs seem to run (Office, IE11, Firefox, some other utils I tried, etc.).
So, did same thing above to another PC with Avast 2015/2028 and same "hang" scenario as above.....luckily stable now.
So, on 3rd machine I uninstalled Avast 9 and Avast cleaner
then did MS update.
Not only did it not hang the install (config) took only few minutes then reboot.
Any chance
Avast's Self Defense Module (Avast 2014 & 2015) is hanging this ?
While the update itself was on few MB in size I did some reading and this update is very intrusive into the O/S.
https://www.winhelp.us/news/146/207/November-s-Patch-Tuesday-squashes-many-critical-bugs.html