I'm using a win2k3 DHCP server in a mixed windows/mac environment and we're having issues with many of our Macs getting IP conflicts. These Macs aren't joined to the domain. They run on local accounts.

When you look on the DHCP server the leases are issued to the Mac, but the Mac clients give an IP Configuration error saying that the IP is in use by an unknown mac address and won't apply the IP address.

Assigning a reservation does fix this and so does spoofing the mac address, but obviously we'd like to fix the root cause. Any ideas?

I've already tried increasing the number of ARP probes to '15' without any luck.