You are experiencing the same thing that I did after the Anniversary update.
My right click would stop working, my spell checker wouldn't work, Task Manager wouldn't open and my computer would get very loggy.
I couldn't open the command prompt either, and sometimes I couldn't shut my computer down.
On my computer it seemed to be related to Google Chrome somehow.
I uninstalled Chrome and my computer worked, I reinstalled it and it worked until I opened Chrome and then it would start the process all over again.
I tried putting in an older version of Chrome and that seemed to work, but then it updated itself and the problems started again.
Right now I'm using Opera, I used Revo Uninstaller to remove Chrome as completely as I could.
As long as I use Opera, or Edge it seems to be OK.
I ran all my malware programs, Sfc /scannow, every diagnostic I have and they all found nothing.
Weird, but I'd like to know if you find that Chrome it what's causing the problems, I thought that it was only me.
I imported all my favorites into Opera and Edge before I uninstalled Chrome.
All good suggestions. Was your W10 pre-loaded on the computer you're having the issues on? Or was it upgraded from an earlier version of windows such as Win7/8.x? If you did upgrade to W10 from an earlier windows, did you remember to run the W10 COMPATIBILITY TEST prior to the upgrade? If not, you should consider re-doing the upgrade, or a W10 clean install and running the Compatibility Test to identify any problem apps, drivers, or hardware (such as BIOS, Chipset, GPU chip/card) with W10. Here's the link for instructions on how to do this: Get Windows 10 app - Check Compatibility Report for Windows 10