The latest 2nd-Tuesday Win updates are available. That infernal KB2952664 is back on the "important" list. I typically make note and uncheck/block it but overlooked doing so on one of my Win7 systems. The result was an irritating change in appearance of the Start Menu, Task Bar, and frames around program windows.
And a consistent/persistent fault advisory bubble at boot-up regarding "Windows could not connect to the System Event Notification Service. This problem prevents limited users from logging in to the system. As an administrative user, you can review the System Event Log for details why the service didn't respond."
Multiple attempts to fix the problem per search suggestions to no avail, I uninstalled KB2952664, and now joy!