New modem doesn't like Airport Extreme

My dad bought a Linksys BEFCMU10, and it won't work with his Airport Extreme. All the connections are right, but its having trouble with DHCP, the Airport can't get a DNS server or IP (it just gives itself a 169 IP).

The modem works fine when connected directly to a computer and when connected through my switch, but the Airport won't even work when its connected to my switch which is connected to the modem.

Anyone have any advice? The airport worked fine with our old modem. Thanks

is the new modem a router also? Basicly does it hand out a 192 ip address when directly conected to it? if so they airport and it could be using conflicting ip ranges.

Nope, just a modem. When I plug it in directly it gives me a real IP, not 192/169/10. I do have the Airport set to give IPs in the 192.168.1.x range, i'll change it to 10.0.0.x when I go over there to see if that helps.

OK, that didn't help.

My dads going to the Apple store to see if they can help, and if not we're getting a Linksys router (I'll be so glad to get the Airport out of there..)