PI integration to SFDC stopped working 2 weeks ago. PI uses SOAP calls to create Account records in SFDC and now fails with the following errror:

com.sap.engine.interfaces.messaging.api.exception.MessagingException: java.io.IOException: Failed to get the input stream from socket: iaik.security.ssl.SSLCertificateException: Peer certificate rejected by ChainVerifier

Any ideas on how to correct?