Comment 55 for bug 197959

I get the same, or a very very similar, problem with an amd64 install on a Gateway MX7515 with a broadcom 4318 wireless chipset and the 2.6.24-15-generic kernel. (using the b43 driver of course)

nm-applet sometimes shows that it connects to a wireless network but (almost) nothing works. I say almost because i can still ping my router and other machines on the network, but domain names do not resolve. However, other times the lights just stay gray and it never connects.

Plugging in an ethernet cable and allowing it to connect that way fixes the problem, and allows a wireless connection to work as expected once the cable is unplugged and nm-applet reconnects to the wireless network.

No changes are made to /etc/resolv.conf when doing this, so the apparent dns problem is likely a symptom of whatever really gets 'fixed' when connecting then disconnecting from a wired network.

Frankly, I have no idea what the problem is, but it happened to me in gutsy with bcm43xx part way through the development cycle and I ultimately resolved to use ndiswrapper.