DWL-2100AP + 2pcs DWL-G700AP + Linux DHCP-server = ARP probs

As written in the header I have as follows:
1pce Linux (Ubuntu)server with a DHCP-, BIND9, Postfix-, Shorewallserver etc..
1pce D-Link DWL2100AP (configured as a AP)
2pcs D-Link DWL-G700AP (configured as Repeaters)

2pcs workstations with WinXP
2pcs workstations with Ubuntu 8.04 DE
1pce iMAC
1pce iPhone

All computers, AP and Repeaters have been assigned static DHCP-addresses based on their respectively MAC-adress, this was done in the DHCP-server.

I have also configured the AP and Repeaters to only accept connections from respectively MAC-address (under Advanced - Filter).

Lately I have seen som ARP flip flops in the syslog and 2 of the users have complained about "IP-collisions".
All the users get the right IP (i.e what is configured in the DHCP-server) when they first log in, after 30sec up to 30 min. the flip flops starts and subsequently the IP-collisions.

QUESTION:
Have I configured the units "right" or "wrong". What do I miss?


Thanks in advance!

//S