I've just installed Ubuntu in a dual boot Linux/Windows setup on an ageing Dell Inspiron 1520. After searching answers on here I got past the Broadcom wireless card/no connectivity issue and the missing splash screens/nvidia proprietary drivers issue, but this one has me beat.
My wireless router is broadcasting its SSID correctly – it is definitely not hidden. The router is set to broadcast the SSID and other devices pick it up fine. However on boot Ubuntu shows no available networks for connection. After poking around I managed to set up a connection manually via 'Connect to hidden wireless network'. This works fine until a reboot, at which point I have to reconnect manually (the connection I set up remains in the drop-down list). If I disconnect without rebooting, the network remains listed under wireless networks and I can reconnect with a single click. I've tried changing all available wireless switches (wifi catcher etc) in the bios and all combinations of the 'Connect automatically' and 'Available to all users' tickboxes in the 'Edit connections' dialogue, but no result.
This is more a convenience thing than a deal breaker but any suggestions would be gratefully received.
Best Answer
I was also having this problem with 12.04. Here are the steps I took to fix the problem.
Had to install firmware-b43-installer and remove bcmwl-kernel-source.
Reboot
At this point my wifi light became active and I could connect if I used the "connect to hidden network" and typed in the name and passcode.
Once I was connected to the wireless network I installed a package called WICD. Now, I only installed this package ... I DID NOT configure anything or remove network-manager.
Reboot
After the reboot, it found my network and automatically connected. I'm not sure why this worked, but I do know that some other packages were installed with wicd. Maybe one of these packages fixed the problem? Not sure, but again I DID NOT remove network-manager after installing WICD.
This has solved the problem for me .... hope this helps you.