Wifi won't connect to certain networks

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http://askubuntu.com – As I write this, I'm in a coffee shop on my laptop, and I am trying to connect to the free wifi network they offer. Every time I select their network from the wifi applet drop down menu, it connects for a second and then disconnects. At the same time, I have my Android phone with me, and it connects to the coffee shop's network without problem. There are a couple of people around me also using the same network with no issues. I asked the staff to check and as far as they can tell there is no problem with their router or anything. I have tried rebooting, but it has not made a difference. I h (HowTos)