Comment 7 for bug 379052

Had the same problem on my Lenovo 300 C200. Curiously I can add the Broadcom BCM 4311 wifi driver from the live CD (System/Administration/Hardware Drivers) but when I installed the beta, the option to add this driver doesnt exist. i.e. System/Administration/Hardware Drivers doesnt show any propriety drivers to add.

As a workaround I rebooted from the live CD again, activated the driver and THEN installed again by clicking the install icon on the desktop. I didn't choose to install from the menu.

After this the driver shows up but I can't get it to activate. I followed the solution above and reinstalled bcmwl-kernel-source from the synaptic package manager after choosing the install CD as a repository source and now the driver can be activated.

A 2 minute fix and all is good