[ubuntu] network problems to external addresses only

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http://ubuntuforums.org – During the update from Precise to the latest beta of Quantal, an age-old tryout of TOR obviously interfered with my upgrade. I de-installed TOR after the upgrade, but now I cannot connect to external computers or ip addresses. The internal stuff works fine; I can use the laptop to configure the router, see it's web page etc. All external addresses give a DNS error that there is no ip attached to this address. What can I do to restore the default settings or deactivate every firewall in the laptop? ()