I just installed Nagios last week. It has been running good with one exception - it is showing some servers to be down when there are not down. If I drill down to the host state information page I see that all checks passed, but there is one line that shows "Status Information Usage:check_nt -H host -v variable -p port] -w warning] -c critical]-l params] -d SHOWALL] -t timeout]"
It should be reporting something like this: "Status Information: PING OK - Packet loss = 0%, RTA = 0.40 ms"
All of my hosts are currently configured the same way. I started out monitoring 24 Windows servers, and initially 2 of them showed as being down. Now I'm up to six servers showing down. Very strange.