ipconflict

I have a couple of users that are continuing to experience ipconflicts w/in our network. We currently have a WIN 2K PDC, with 3 NT BDCs. I have replaced the NICs in the PCs affected from a 3CSOHO to 3C905B-TX and 3C905C-TX cards. I have also changed the switch ports that the users are attached to. We are strictly a DHCP network w/ no static IPs w/in the scope.

Anyone have ideas as to why I received ipconflicts in a DHCP environment?

Thanks.