Problem with 3945ABG: Internal wifi cannot associate with AP
T60 continually failed to associate with a Linksys WRT54g AP. PCMCIA Prism2-based cards worked fine. I tried both the ipw3945 and iwlwifi non-free firmware available using Sidux (Debian Sid).
The card would configure properly and respond to commands but would not associate.
The solution was simple, I had disabled ESSID broadcast on my AP. Enabling ESSID broadcast solved the problem. This also solved the same problem with a Linksys WPC11 ver 2.6 with USB interface. The non-free at76c50x firmware worked properly, but it also would not associate without ESSID broadcast enabled.