Comment 5 for bug 760452

New update:

The problem was more complex and the agent was just a "victim" of something bigger.
Basically, DBUS was not starting properly.
Dbus starts at boot and queries LDAP. Since NSCD is not started yet, dbus has problems.
Ubuntu 10.04 is using upstart for many services, including DBUS. Nscd is still relying on symlinks, so the startup order can't be modified easily.

The problem has been solved with a modification of the dbus upstart script and creating a custom Nscd upstart script, to make dbus depend on nscd. Briefly, something of this kind:

upstart dbus.conf:

"start on started nscd"

upstart nscd.conf

"description "name service cache daemon"

start on local-filesystems
stop on runlevel [06]

#expect fork
pre-start script
    mkdir -p /var/run/nscd
end script

exec /usr/sbin/nscd -f /etc/nscd.conf"

You can close this bug, then, because it's definitely not a polkit-agent issue :)