I installed Ubuntu 13.04 on a laptop today and was surprised when it would see my wireless network but fail to connect to it.
After a few quick searches on another machine, it became apparent that this was an issue related to the chipset in use on my wireless adapter – the Broadcom 4313. Turns out the default driver that gets loaded for it is broken. Thankfully, after about five minutes of bouncing through Google results, I found “The Workaround“.
The ubuntuforums.org user, varunendra, worked out how to fix it and posted a thorough – albeit slightly intimidating – guide. After carefully following all the steps, sweating a little, and a restart, I was online!