After running Windows 10 for 6 weeks on my Dell Optiplex 790 desktop I got this critical error message. Tried several suggested fixes including unstalling a new application that proved to be imcompatible (Sling). The fix that worked for me was to do a safe boot with networking on, allow the computer to finish "working its magic" and then reboot. Then go back into normal boot mode and start again. This cleared up the problem.