According to people having the same bug in Gentoo, running sudo chmod o+x /usr/libexec/dbus-daemon-launch-helper solves this bug. Could you report if it's also a solution for you? Thanks!
** Changed in: system-tools-backends (Ubuntu) Status: Triaged => Incomplete -- You received this bug notification because you are a member of Ubuntu Desktop Bugs, which is subscribed to system-tools-backends in ubuntu. https://bugs.launchpad.net/bugs/574078 Title: Fails to launch modules: "Can't locate Net/DBus.pm in @INC" -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs