upgrade to F12, nautilus wont start - dbus

[David Timms <dtimms iinet net au>]

I'm having no luck starting nautilus after my upgrade.
$ time nautilus

(nautilus:24582): Unique-DBus-WARNING **: Error while sending message: 
Did not receive a reply. Possible causes include: the remote application 
did not send a reply, the message bus security policy blocked the reply, 
the reply timeout expired, or the network connection was broken.

(nautilus:24582): Unique-DBus-WARNING **: Error while sending message: 
Did not receive a reply. Possible causes include: the remote application 
did not send a reply, the message bus security policy blocked the reply, 
the reply timeout expired, or the network connection was broken.

real	0m50.115s
user	0m0.026s
sys	0m0.006s
$

Reading elsewhere, people were asked if the following works:
$ dbus-launch nautilus
Initializing nautilus-gdu extension
Warning: Unable to create "trees" RDF storage.
Performance can be improved by upgrading librdf.

(plugin-scanner:24604): GLib-GObject-WARNING **: cannot register 
existing type `GstSignalProcessor'

(plugin-scanner:24604): GLib-CRITICAL **: g_once_init_leave: assertion 
`initialization_value != 0' failed

(plugin-scanner:24604): GLib-GObject-CRITICAL **: 
g_type_register_static: assertion `parent_type > 0' failed

(plugin-scanner:24604): GStreamer-CRITICAL **: gst_element_register: 
assertion `g_type_is_a (type, GST_TYPE_ELEMENT)' failed

It's still sitting there. No window or indicator for a nautilus window 
is drawn.

[yes, I first asked about this issue in fedora-test-list, without a 
solution so far].

DaveT.