Airport Extreme and Zyxel Prestige 324

Hi. I have a Zyxel Prestige 324 router and my Airport extreme (firmware 7.2.1) is connected via bridge mode (I want it to serve as an access point). However, once I save the configuration and update my airport extreme, the DHCP server on my Prestige 324 dies and sends out 169.x.x.x IP addresses -- and thus kills the internet connection on my entire network. There's no way to bring the DHCP server back up unless I unplug the airport extreme from the network and reset my router.

I reset my airport extreme to factory defaults, thinking it was a faulty configuration, but the moment I set the airport extreme to bridge mode, it kills the DHCP again.

I'm not sure if this description is helpful enough, but if you need more information, please let me know. Thank you in advance.