TCP/IP settings disappeared all a sudden!?

My Setup: three Macs, two Time Machines, one TM set up as main Airport, the other as an extended Airport. Everything connected via Airport.

Today, the iMac is not connecting to the internet. The Airport antenna on the tool bar shows a strong signal, and when I pull down on it, it shows it's connected, but in Network Preferences is says Not Connected (see screenshot 1).

Then, in the TCP/IP tab, all my setting are gone! (screenshot 2). The settings in my laptops are just fine.

I power-cycled everything, but the iMac is still without connection.

Could the Airport card/software be the problem?

I just tried connecting the iMac via Ethernet, and that connects to the internet just fine. So it must be the Airport.

Run the Apple Hardware Test on your iMac to see if it's the airport card that has failed. Also, check your System Profiler.app to see if it shows the airport card.

The Airport Card shows up in the System Profiler as "Connected", and shows all the appropriate Network Information (like my other machines).

However, when I try to do the Hardware Test (restart holding the D key) the Hardware Test does not come up. I also tried it with the appropriate install disk (starting and holding the D key), but I don't get the Hardware Test screen.

I had the same issue on my 2011 MBA running 10.8 last night. Rebooted several times, cycled wireless, etc... nothing helped. Rebooted my Gen2 AirPort Extreme twice and everything was working again. My wife's 2008 MB Unibody running 10.6.8 (WiFi connected) and my wired 2009 Mini running 10.7.4 (wired connection) experienced no issues while the MBA was offline. My iPhone 4 had no issues either. Weird stuff. If it happens again I'll open the Console and see what's going on under the hood. I had the same symptoms where my Network Pref's said I had no IP address.

OK... I tried everything several times: restarted and restarted, checked the system profiler, tried to do the hardware test from the HD and Install Disk (neither worked), finally turned the computer off and went for a little bike ride. Came back turned it on, and everything is back to normal. What????

So, I guess in the future, I need to stop working on these problems sooner and go for a bike ride.

Glad it worked itself out. Please post again if the issue persists. Thus far, I'm coming up on 24 hours without a recurrence. Fingers crossed.