Helo again,
That is not the System Managment homepage that's the event. The System Management Homepage is located on the destination server on http://machinename.fqdn:2381
On this page you can see the status of your server, if you choose Logs from the menu and look for the Integrated Management Log entry there you should find your Post error. From here you can clear the event. If the event is cleared you won't get the post error in SIM every time you restart the server or restart the HP agents.