Internet Sharing stuck on after 10.7.3 update

I use Internet Sharing at work to create a local WiFi network (sharing the GigE connection) for my various iOS and tablet devices to connect through. After the 10.7.3 update, I cannot turn sharing off after I unplug the Ethernet cable. All the checkboxes in the system pref pane are cleared, but I am unable to join a WiFi network.

After I plug the Ethernet back in, I can then disable sharing, but only while it's plugged in.

As best I can guess, there might be some xinetd cruft laying around, but I haven't the slightest clue as to how to look for it or fix it. Any ideas?

Solution 1:

I found a relatively simple solution not involving a system restart - just bring the WiFi interface down and then back up:

$ sudo ifconfig en0 down
$ sudo ifconfig en0 up

In my case en0 is the AirPort interface of my MacBook Air.

Note that turning the AirPort off and on again doesn't work, but bringing the interface down does the job.