Exactly the same problem here. Fresh 8.04 Ubuntu install - fully updated as of today, 02 June. The only actions taken were:
1. Full update via Synaptic 2. Set static IP via Network Manager 3. Add machine to Active Directory domain using Likewise Open 4. Reboot Attempting to unlock Network Manager (or Users) results in the error message and a full desktop lock - only crtl-alt-bkspc works. Have tried reinstalling policykit - same problem. Have checked /etc/hosts and the default did not have "machinename" in the 127.0.0.1 line. Added machine name and retested. Failure still occurred. -- [users-admin] Unlock -> "Could not authenticate. An unexpected error has occurred." https://bugs.launchpad.net/bugs/194496 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
