This issue was cross-posted on the Microsoft Community.  Per a suggestion there, we ran the McAfee Consumer Products Removal Tool, which did not appear to fix the problem, even after multiple restarts. Then we were forced to run the Fall Creator's Update -- and that did indeed fix the problem. Thanks for your help. Joe Griggs
I have a new Dell Inspiron 7579 computer that was working fine and updated current  before the October Cumulative Update.  It has Windows 10 Home installed. After Update KB4041676 was applied on October 10th, it now takes waiting 5 minutes for a Black screen that appears after login to go away, and allow use of the machine.  I read that HP users had a similar problem after the September updates. Example: [URL]#M232344     I have tried uninstalling KB404167 and doing a system restore to before it applied - which fixed the problem temporarily. Unfortunately, since Home users cannot defer updates, the update promptly reapplied and the problem returned.   I saw that Microsoft issued a fix for this problem in September (presumably in response to the HP users) Here:  [URL]    When I tried to run that update, my machine blue screened on restart with the message Inaccessible Boot Device.  I successfully recovered by using System Restore in the Recovery tools.   I also tried downloading KB4041676 from the Update catalog, uninstalling it, rebooting, and installing it standalone -- and still have the problem.  I have now uninstalled and reinstalled the update several times, and no longer have an accessible restore point before the update was first applied.   Disabling the App Readiness service does indeed eliminate the 5 minute delay.   I have the update, and the Flash Player update installed, and both the App readiness service and the Windows Update service disabled to make the machine usable in the short term.   Suggestions to troubleshoot / fix the problem?
App Readiness svc causes 5 minute login delay after KB4041676