If you use WEP like me, here is how to solve the problem without using or installing wicd.
Firstly, test that it will work by first stopping the network manager service:
This is to verify that you are running independently of network-manager.
Then edit /etc/network/interfaces like this:
iface wlan0 inet dhcp
pre-up wpa_supplicant -iwlan0 -c/etc/wpa_supplicant.conf &
post-down kill -9 `pidof wpa_supplicant`
Depending on your wifi card, you may need to use the -D option for wpa_supplicant.
Then, edit /etc/wpa_supplicant.conf (this will probably be created as a new file) and make it look like this:
# Static WEP keys
(The above code was modified from examples in /usr/share/doc/wpa_supplicant/examples)
Then restart networking:
Verify that your wlan0 interface has an IP and you can ping other hosts on your LAN. If it works you may safely remove network-manager via apt-get like i did.