eth0 conflict

[capacity77 at tin.it]

Hi there!
Anyone has an idea why it happens that hostap works good only if I ifconfig
eth0 down?
If i don't do it, the dhcp server gives the IP but then it's not even able
to ping. 
And if I do /etc/init.d/dhcp restart when eth0 is still up, I get the error
message
Starting DHCP server: dhcpd failed to start - check syslog for diagnostics

The tail syslog is this:
Dec  9 15:04:03 tonga kernel: wifi0: 00:09:5b:ba:16:13 assoc_cb - STA associated
Dec  9 15:07:34 tonga dhcpd: Multiple interfaces match the same subnet:
wifi0 wlan0
Dec  9 15:07:34 tonga dhcpd: Multiple interfaces match the same shared network:
wifi0 wlan0
Dec  9 15:07:34 tonga dhcpd: wifi0: unknown hardware address type 801
Dec  9 15:07:34 tonga dhcpd: No subnet declaration for eth0 (143.225.229.212).
Dec  9 15:07:34 tonga dhcpd: Please write a subnet declaration in your dhcpd.conf
file for the
Dec  9 15:07:34 tonga dhcpd: network segment to which interface eth0 is
attached.
Dec  9 15:07:34 tonga dhcpd: exiting.
Dec  9 15:08:26 tonga kernel: wifi0: 00:09:5b:ba:16:13 auth_cb - alg=0 trans#=2
status=0 - STA authenticated
Dec  9 15:08:26 tonga kernel: wifi0: 00:09:5b:ba:16:13 assoc_cb - STA associated

Any hint for me?
Thanks a lot!
Dom