Unexpected error message when trying to connect AirPort Extreme as a new base station
I am trying to configure a new AirPort Extreme to replace my old one that died recently. I am using Airport Utility 6.3.8. Whenever I try to make the connection, I get the message "An unexpected error occurred." Utility seems to find the router, but I can't get past this message to set up the network further. I have performed the factory reset on the Extreme (purchased new from Apple), but the same thing keeps happening. Suggestions, please.
iMac, Mac OS X (10.6.7), 500GB HD, 4 GB 1333 MHz DDR3