Thanks for replying Teen Titan,
I just double checked both my copy of ARD and the server. My ARD client is set to use the server and the server has the options set to use it's own task server and to allow remote connections to this server. I took a look in the logs that could give me a clue as to what might be going on and I noticed this.
10/6/11 8:41:57.565 AM Remote Desktop: [Computer initWithDescriptor] CFStringToIPv6Address failed to convert string [::] to an IP address.
10/6/11 8:41:57.602 AM Remote Desktop: [Computer initWithDescriptor] CFStringToIPv6Address failed to convert string [::] to an IP address.
10/6/11 8:41:57.605 AM Remote Desktop: [Computer initWithDescriptor] CFStringToIPv6Address failed to convert string [::] to an IP address.
10/6/11 8:41:57.617 AM Remote Desktop: [Computer initWithDescriptor] CFStringToIPv6Address failed to convert string [::] to an IP address.
10/6/11 8:41:57.619 AM Remote Desktop: [Computer initWithDescriptor] CFStringToIPv6Address failed to convert string [::] to an IP address.
10/6/11 8:41:57.622 AM Remote Desktop: [Computer initWithDescriptor] CFStringToIPv6Address failed to convert string [::] to an IP address.
10/6/11 8:41:57.623 AM Remote Desktop: [Computer initWithDescriptor] CFStringToIPv6Address failed to convert string [::] to an IP address.
10/6/11 8:41:57.624 AM Remote Desktop: [Computer initWithDescriptor] CFStringToIPv6Address failed to convert string [::] to an IP address.
10/6/11 8:41:57.626 AM Remote Desktop: [Computer initWithDescriptor] CFStringToIPv6Address failed to convert string [::] to an IP address.
10/6/11 8:45:06.745 AM ARDAgent: theAdminKeyRef key not found (001B6393A9AA, 0x10235cde0).
10/6/11 8:45:06.746 AM ARDAgent: Encryption key not found for client.
10/6/11 8:45:06.866 AM ARDAgent: theAdminKeyRef key not found (001B6393A9AA, 0x7f8bd1e07bf0).
10/6/11 8:45:06.867 AM ARDAgent: Encryption key not found for client.
10/6/11 8:45:07.697 AM ARDAgent: theAdminKeyRef key not found (001B6393A9AA, 0x7f8bd1e07bf0).
10/6/11 8:45:07.697 AM ARDAgent: Encryption key not found for client.
10/6/11 8:45:08.222 AM ARDAgent: theAdminKeyRef key not found (001B6393A9AA, 0x7f8bd1e07bf0).
10/6/11 8:45:08.223 AM ARDAgent: Encryption key not found for client.
That prompted me to have a look at the server's IPv6 address which, for what I can tell, is a bit odd. I'm going to check with my admins and see if they have any advice. I'll post back if I find anything but I'd also appreciate any advice that others can offer.