[ubuntu] Can't Connect to Router; Have to Restart

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http://ubuntuforums.org – Hi I am running Ubuntu 12.10. My laptop connects to a wireless router. Now and then, I use my broadband modem. Thus, I disconnect from the router. When I want to connect to my router again, it keeps on popping up a dialog box with the password. I have to restart the laptop in order to connect to the router again. When I restart the laptop, it connects to the router automatically. I tried: sudo /etc/init.d/networking restart Instead, my whole screen gets messed up and I have to restart the laptop. Any idea how I can connect to the router after having used my broadband modem? (Hardware)