Is this ManageEngine's greatest kept secret?  I see no answers here on this issue, just a question a user posed and was never responded to.  Nothing on search engines .... like we can't speak of this lest it get erased.

I was happily humming along and all of the sudden two machines are reporting back "Health Not Available". I've ruled out firewall and antivirus.  So what gives with this error?  Why would this suddenly appear on 2 out of 19 managed machines where it wasn't before?