The certificate for a computer that is attempting to communicate with Operations Manager is not trusted. The remote computer will not be monitored until the problem with the certificate is resolved.
The certificate for the remote computer is issued by a certificate authority that is not trusted by the server running Operations Manager.
View the details for the alert to identify the computer that is using an untrusted certificate. Configure the source computer to use a trusted certificate or configure the server running Operations Manager to trust the certificate authority that issued the certificate. For information about configuring certificates refer to the following:
Managing Certificates in Operations Manager (http://go.microsoft.com/fwlink/?LinkID=227146).
Managing Certificates from the Windows Server topics on TechNet (http://technet.microsoft.com/en-us/library/cc771377.aspx).
For additional information on certificates and security, see PKI Technologies (http://technet.microsoft.com/en-us/library/cc779826(WS.10).aspx).