Wireless internet is connected to an open network but has no internet - 12.04

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http://askubuntu.com – I just installed Ubuntu on my laptop yesterday and it connected to the wireless fine. Then I took it to school, put it on their wired connection, downloaded some stuff, and now the wireless doesn't work. At first it would detect networks, but not connect. I restarted it and now it can connect, but it acts like it doesn't have internet in the browser. Wired connection still works fine on it. I know it isn't the network because my ipad is working on the wireless connection fine. I found another solution on here switching the security settings for the wireless, but this is the apartment's wir (HowTos)