I encountered this same problem after upgrading from gutsy to hardy. After trying to resolve connection problems which were messed up after the upgrade the sudo stopped working. It happened when I disabled my wireless and lan connection from kde network management tools. Booting in recovery mode and adding the host name back did fix the problem.
I find this very serious problem since ubuntu relies so heavily on sudo (the lack of root account) and if that command fails there is no way to do anything. sudo should not depend on network configurations. It sounds very very dangerous!
I encountered this same problem after upgrading from gutsy to hardy. After trying to resolve connection problems which were messed up after the upgrade the sudo stopped working. It happened when I disabled my wireless and lan connection from kde network management tools. Booting in recovery mode and adding the host name back did fix the problem.
I find this very serious problem since ubuntu relies so heavily on sudo (the lack of root account) and if that command fails there is no way to do anything. sudo should not depend on network configurations. It sounds very very dangerous!