Eu não sou especialista nisso, mas acho que o erro estaria aqui (pode estar aqui)
// at this first line message is shown of Activation is failed.
1) Apr 1 23:32:01 NetworkManager[901]: <warn> Activation (wlan0) failed.
// device state changing failed without any reason (i don't know about this, "[120 30 0]")
2) Apr 1 23:32:01 NetworkManager[901]: <info> (wlan0): device state change: failed -> disconnected (reason 'none') [120 30 0]
// deactivation.
3) Apr 1 23:32:01 NetworkManager[901]: <info> (wlan0): deactivating device (reason 'none') [0]
// if (wlan0) is not activated the what is a use of service that showing here is activating?
4) Apr 1 23:32:01 dbus[885]: [system] Activating service name='org.freedesktop.nm_dispatcher' (using servicehelper)
// no coments on this service.
5) Apr 1 23:32:01 dbus[885]: [system] Successfully activated service 'org.freedesktop.nm_dispatcher'
// refer something for error's on setting mode with no. "2". (confusing question|sorry)
6) Apr 1 23:32:01 NetworkManager[901]: <error> [1333303321.565351] [nm-device-wifi.c:1815] nm_device_wifi_set_mode(): (wlan0): error setting mode 2
se isso não é uma solução para sua pergunta, então desculpe bro, eu não posso fazer nada para você ...