Comment 20 for bug 653829

Stardate 2012 ...

Changed my AP to N only.
Win7 laptop still connected but not my Ubuntu 12.4 Lenovo laptop with
03:00.0 Network controller: Intel Corporation Centrino Advanced-N 6205 (rev 34)

After searching a bit i found this thread, and the note from Filiprino above sorted me out.
Had to switch "WMM(Wi-Fi Multimedia):" from off to auto. Leaving the ap on N only.

Suddenly ubuntu connected using WPA-PSK without any problems.
Even solved the problem for my Android ICS phone's wifi.