The error log message "POP3 unable to connect to port monitor" comes from VirusScanner's AutoEmailScan. Sometimes other services or processes interfere with attempts to connect to the POP3 port. Fortunately AutoEmailScan continues to try to connect until a successful connection is made. If the AutoEmailScan service is unable to connect after several attempts, you will see an error message from SystemSuite. 

Seeing this message in your log files is normal and not a cause for concern. If you continue to see this message in the log files, you may want to try disabling some of the unused third-party services that load automatically at startup. Contact the program vendor for the service to find out if it is necessary to have that service running before you disable it permanently.