Hi All, I am a newcomer in this list and new with using the product. I am attempting to configure Nagios NRPE for UNIX in the Nagios Monitoring server and NAGIOS NRPE for Windows in the monitored XP PC. The NRPE daemon in the UNIX servers and the NRPE service in the Windows PC appear both running. The Nagios console is able to show me the Windows XP PC and its ping but the CPU load service shows "critical" and the message " CHECK_NRPE: Error - Could not complete SSL handshake. " I have changed the windows.cfg syntax in the UNIX monitoring server from "check_nt" syntax to "check_nrpe" but the result was a different error. define service{ use generic-service host_name windowsXP service_description CPU Load check_command check_nrpe!pdm_cpuload } Any idea what the problem might be? Does the NRPE versions need to match the same operating system? Do I need to manage NRPE UNIX clients with a UNIX NRPE Monitoring server and NRPE Windows clients with a Windows NRPE Monitoring server? Thanks. Regards Salvo