You have the medibuntu repositories :O With a search in Google I found this http://goo.gl/zNn0L (run in Terminal and enter your admin password): sudo rm /var/lib/apt/lists/* -vf
Another similar bug: https://answers.launchpad.net/ubuntu/+source/apt/+question/202117 :) Good luck! -- You received this bug notification because you are a member of Gufw Developers, which is subscribed to Gufw. https://bugs.launchpad.net/bugs/1070985 Title: can update system Status in Gufw: Invalid Bug description: E: Encountered a section with no Package: header E: Problem with MergeList /var/lib/apt/lists/packages.medibuntu.org_dists_precise_free_binary-i386_Packages E: Kunde inte tolka eller öppna pakelistorna eller tillståndsfilen. E: _cache->open() failed, please report. To manage notifications about this bug go to: https://bugs.launchpad.net/gui-ufw/+bug/1070985/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~gufw-developers Post to : [email protected] Unsubscribe : https://launchpad.net/~gufw-developers More help : https://help.launchpad.net/ListHelp

