Could not fetch information from server


I installed nagios 3.0.3 on Fedora 8.
I followed the quick guide on nagios site, everything ok,but I have a little problem with the client.
I get the following error on Nagios page.
"Could not fetch information from server"
I have this error in all service for the client ( two WIN XP)

If i check the log on the windows client I see this:
error:.\NSCAThread.cpp:208: <<< Failed to initalize encryption header!
2008-07-24 13:34:24: error:.\NSClientListener.cpp:296: Unauthorized access from:

Someone can help me?
thanks very much


well, first thing would be worth checking firewall in both client and server. I had problem with my text xp machine. I found the firewall was the main issue. you could try telnet from server to client on port you are using. See if that connects or not. If firewall is configured properly perhaps looking into config file in client side.