IP address conflict / duplicate computers with same IP w/ DHCP server

I am running a network of about 10 PCs and 10 VOIP phones.

Every once in a while I am getting “duplicate use detected” errors where one machine already has a DHCP address and another is given that address and I get the error of duplicate IPs, seems like the system overflows and it can’t dish out more DHCP addresses or the network card of the machine is showing as already connected and won’t connect it again.

The message I am getting is:

The system detected an address conflict for IP address with the system having network hardware address . Network operations on this system may be disrupted as a result.

This happening basically locks up the whole systems and everything needs to be rebooted.

I found something in this article but it seems related to older OSes:
http://support.microsoft.com/kb/174929/en-us

Thanks for your help in advance.