Service checks not working

Hi I am new to nagios and haveing some problems…

The service checks (eg disk_free) on my Nagios 3.0.2 instlation are not running, they are just sitting at the top of the Scheduling Queue.

The Host is being marked as up (via the ping test)

I did some sniffing and can not see and connections going out of the server or going into the client.
If i manually telnet to port 5666 of the client the connection is made.

The only error i can find are in the var/nagios.log

[1213088995] Warning: The check of service 'disk_free' on host 'server1' looks like it was orphaned (results never came back). I'm scheduling an immediate check of the service... [1213089055] Warning: The check of service 'ssh' on host 'server1' looks like it was orphaned (results never came back). I'm scheduling an immediate check of the service...

If i run the command manually i get a successful reply

/opt/nagios/nrpe/libexec/check_nrpe -t 30 -H server1 -c check_disk -a 20 10 /
DISK OK - free space: / 5358 MB (73% inode=99%);| /=1959MB;7298;7308;0;7318

Can some one please point me in the direction of a fix, as i said i am new to Nagios so could be missing something obvious,
Thanks for any help.

Nagios server is running on a zone in Solaris 10

here are my config files…

# cat disk_free.cfg
define service {
        use                     generic-service
        hostgroup_name          servers-solaris
        service_description     disk_free
        check_command           nrpe_check_disk!20!10!/
}


# cat nrpe_check_disk.cfg
define command {
        command_name    nrpe_check_disk
        command_line    /opt/nagios/nrpe/libexec/check_nrpe -t 30 -H $HOSTADDRESS$ -c check_disk -a $ARG1$ $ARG2$ $ARG3$
}