I just got my Extreme N today and while the wired connection works fine when I enable wireless (in any configuration -- security, no security, b only, b and g, auto channel, specific channel, etc) it resets the router and reboots, I have access through wired again, but the wireless settings did not stick. It sets the wireless name to it's default along with all other settings and then does not work. I cannot see the wifi network (even directly typing in the name does not work) and no matter how many times I reset the router (manually and through software) the settings always revert to default and does not broadcast. Any ideas?
Your AirPort Extreme should definitely NOT have a MAC address of all 0's. You should try to hard reset by holding in the reset button on the back for more than 5 seconds, but if you still have a bad MAC address you should take the base station to the nearest genius bar or call apple and get a replacement.