Certificates and the agent
The Verisign Root Certificate Authority (CA) must be current. This is required because the agent software is signed using a Verisign certificate. If your certificate is not current, you must download the Root CA certificate and install it to the
Local Computer\Trusted Root Certification Authority store on the server hosting the agent.
For more information, search for "Add the Certificates Snap-in to an MMC" at technet.microsoft.com.