wireless router ap access point access fail

Question

I can not connect to internet by wireless router after some months with ubuntu 10.04. I can connect with the same portable but with win OS.

My SO is ubuntu 10.04 linux 2.6.32-41 arch SMP i686. The internet wireless network controller is Atheros AR9285 chipset (pci express) Kernel module ath9k

I have tried a command line connection:

$ sudo /etc/init.d/network-manager stop     #stop gui network manager
$ iwconfig wlan0 essid WLAN_3C key s:C001D20550B3C
$ ifconfig

  Access Point: NOT-ASSOCIATED

$ dmesg

    ... AP 00:1a:2b:08:60:49 associated

Is the SO has connected to router for booting long ( associated message), after boot and login why the connection to router is not possible by network-manager or command line (NOT associated message)?

Thanks in advance