Hi,
As the message suggests, contact your network administrator. if you *are*
the network administrator, then you should be a worried. If you can get
downtime, try dropping the interface (not remotely ;-) and then
tracerouting to the ip from another host. This should be a good starting
point. Also check ARP tables on local routers.
However, while a duplicate IP is possible, I have also seen a case where a
Windows machine with NIC teaming (running Landesk) was spoofing ARP
requests (how nice) on behalf of the unix box. In the end we had to place
the Landesk box on a different subnet so it couldn't asume authority over
other other servers responding to ARP within the original subnet.
Regards.