Agent was stopped so performance plan wasn’t running.
Errors in Agent Log: delay_between_response attribute (10 sec) of alert (9) is less
than poll interval for this alert (20 sec)
Research led to http://www.sqlservercentral.com/articles/Administration/3177/ and CTRL+A copy/pasted the solution into notepad.
Changed this registry key: EventLogPeekInterval from hex 14 to hex a which in decimal equals 10 seconds. Restarted Agent and errors went away.