uninstalled, reinstalled, problem went away.  For 2 weeks.  Then repeated uninstall, reinstall and problem went away.  For 2 days.

Windows 10 is current on maintenance.  Live Mail 2011 was installed when upgrade to Windows 10 occurred 2 months ago.  It had the same problem so installed Mail 2012 which 'sort of' fixed the problem.  Until 2 weeks ago.

There are MANY hits on this problem but no solution I've found that applies, other than the uninstall/reinstall that only works for a while.