Stale DHCP Reservation

When I tried to PXE boot a test PC, I couldn't get a DHCP address because there this PCs MAC had a duplicate DHCP reservation. The error I got was "ProxyDHCP service did not reply to request on port 4011". Removing the DHCP reservation for this MAC solved the problem. Thankfully, Windows 2003 Server DHCP labelled the reservation BAD_ADDRESS for me.