I have 12.10 ubuntu and when I try to remove / install programs I get notification :
Software can't be installed or removed because the authentication service is not available.
(org.freedesktop.PolicyKit.Error.Failed: ('system-bus-name', {'name': ':1.104'}): org.debian.apt.install-or-remove-packages
When I log in as root user (instead of user account that I regulary use) i have no problems.
org.freedesktop.PolicyKit.Error.Failed: ('system-bus-name', {'name': ':1.44'}): org.debian.apt.install-file
(I already checked: Policy kit is in autostart)