Running Ubuntu 12.04, I can't seem to get Internet access even though the Desktop icon says I am connected. So I reset the router, and everything seems to work fine, including after restarting the computer, but when I set a passphrase for the router I am unable to connect, no matter if it's Firefox, ssh, sftp, etc. Please see this question for details I posted regarding the lack of connectivity.
The security I set is WPA Personal. I should also mention that I was able to connect to a different, secured wireless network, but am still unable to connect to my own. Please let me know if you need more details!