My 2nd generation Extreme began to behave strangely; my MacBook Pro Airport Utility image showed a different front light to the actual unit and I kept losing internet or disk connection. I worked out it was on the verge of packing up so I purchased a brand new 5th generation model from Apple. I took all the connections out from the back of the old one, replaced the power supply with the new one and plugged it all back together again - instantly I was connected to the internet which was a bit of a surprise, not having entered any settings yet. Still I guess the internet settings are on the Billionaire Bipac Ethernet ADSL Modem rather than on the Extreme. So far, so good. Next I opened the new version of the AirPort Utility. Eventually it saw my new unit. It tried to gather information about the new Extreme. Then a message came up. 'An unexpected error occurred. Try again.' How very helpful. An error. What a useful message, telling me exactly what has gone wrong and how to sort it. Not. So I decided to open AirPort Utility 5.6. Well this really was a surprise! There I had two units, my old one (which I had just unplugged) resplendent with green light despite the fact that it had apparently been reporting problems; and the new one, waiting to be set up. I clicked 'continue' and waited. Then I got the message "An error occurred while reading the configuration. Make sure your Apple Wi-Fi base station is plugged in and in range of your computer or connected via Ethernet and try again. (-6753)" At about four feet away there shouldn't have been any problem and of course it was plugged in or there wouldn't have been any lights showing on the unit. I do hope I'm going to be able to tell the difference between the old and new Extremes after spending all that money on a new one! So now that I've had similar problems with both my base stations I surmise that it must be some kind of corruption on my Mac. Has anyone any idea what I should delete and reinstall to get it working properly? I'd be so grateful for a bit of help here as at the moment I have an unprotected network that needs sewing up!