Gratuitous Arp broadcast

I work in the IT department for my home county. We have 16 servers with 10 of them running Windows 2000 server, and the other 6 running Windows Server 2003. The other day I was using ethereal to monitor traffic on the LAN and I noticed that two of my Server 2003 boxes were broadcasting a gratuitious arp message asking “Who has 192.168.30.32?” That IP address does not exist in my network, and I have not been able to figure out why those messages are being broadcast every two seconds from those two servers. Any thoughts would be appreciated.