DHCP settings become unusable again...

I bought an airport extreme december 20th. I setup everything correctly. I used DHCP from a cable modem and connected 3 ethernet connections a usb printer and a laptop.

30 days (Jan 19, 2008) later my airport reported a problem stating that the DHCP number was invalid. It was reporting a 69.x.x.x number or 169.x.x.x number, basically this ip number that sometimes comes up and is recognizable as a PROBLEM.

I disconnected the airport and connected a pc directly to the cable modem and the internet came thru. I went to a few sites and things worked. I connected the airport back to the cable modem and tried to get the DHCP part of Airport Utility to get that number going correctly. After failing at this I took the Airport Extreme back to best buy and exchanged it for another one.

I installed the new Airport Extreme, and things went alright just like the 1st one. After a week though during the night the DHCP problem happened again, but fixed itself during the night, and the Airport Extreme reported the problem.

Now on Feb 26, 2008. The same problem is back again. The DHCP number is bad. But this time I was prepared. I have 3 different IP numbers that were leased that I took note of. So with these numbers I went to the DHCP part of the Airport Utility, and changed it to static ip and put one of those numbers in. After getting that in I went to Safari and things worked.

This is not a Long Term Solution. I have to be able to changed the Airport to DHCP from the cable modem and lease an ip number.

I can't fix this, does anyone know how to reset it hard enough? Or make it so this DHCP problem to come up again?

Laters...