One of the most recent problems I stumbled upon while running Backtrack, or any other linux distro for that matter is setting the region on a wireless card. The typical procedure is :
iwconfig wlan0 channel 13
And commonly you will get
error for wireless regquest ''set frequency''
set failed on device wlan0 ; invalid arugment
There is an easy fix for this that will allow you to change the region mode your wireless adapter is in.
iw reg set FR
iw reg set US
More on IW here.