Comment 10 for bug 289912

Ya, ask of 24 October 2009, this is still a problem.. one day wifi is working fine, next day it isn't. To fix: plug the computer into a wired network connection and select:

Administration -> Software Sources -> Updates and tick hardy-backports (or whatever your distro name is now, "backports" being the important part). It will ask you to update, say yes.

Then do:

sudo apt-get install linux-backports-modules-hardy

(or whatever your distro name is now, "linux-backports-modules-" being the important part). Or use synapic package manager to do this.

And reboot. If you still have troubles, you may need to go into Administration -> Hardware Drivers and uncheck one of the Atheros drivers.. you want HAL and the 5xxx driver.. you don't want the other one.

This is painfully annoying and it would be great if the package manager didn't crud up stuff that was working perfectly fine thank you.