gnome does not start after an update

[evgen]

ubuntu 10.04 (fresh install) was working good, before it was restarted after an update this week.
from this point gnome does not load properly i.e. an empty desktop with a background image appear. panels, desktop icons are not present. 10-30 secs later a mouse pointer appear with a pop-up window without borders with an error message:
"No system tray detected on this system. Unable to start, exiting.". after clicking on OK button, mouse pointer turns into a black X and does not react any more.

here is the output of the xsession-errors file:

$ cat ~/.xsession-errors
/etc/gdm/Xsession: Beginning session setup...
Setting IM through im-switch for locale=de_DE.
Start IM through /home/mariya/.xinput.d/de_DE linked to /etc/X11/xinit/xinput.d/none.
gnome-session[1027]: WARNING: No required applications specified
GNOME_KEYRING_CONTROL=/tmp/keyring-cyyPsN
GNOME_KEYRING_PID=1123
GNOME_KEYRING_CONTROL=/tmp/keyring-cyyPsN
SSH_AUTH_SOCK=/tmp/keyring-cyyPsN/ssh
GNOME_KEYRING_CONTROL=/tmp/keyring-cyyPsN
SSH_AUTH_SOCK=/tmp/keyring-cyyPsN/ssh

(polkit-gnome-authentication-agent-1:1146): GLib-GObject-WARNING **: cannot register existing type `_PolkitError'

(polkit-gnome-authentication-agent-1:1146): GLib-CRITICAL **: g_once_init_leave: assertion `initialization_value != 0' failed
** (nm-applet:1145): DEBUG: old state indicates that this was not a disconnect 0

(gnome-power-manager:1141): GLib-GObject-WARNING **: /build/buildd/glib2.0-2.24.1/gobject/gsignal.c:2273: signal `proxy-status' is invalid for instance `0x9321838'

** (gnome-power-manager:1141): WARNING **: Either HAL or DBUS are not working!

** (gnome-power-manager:1141): WARNING **: proxy failed

** (gnome-power-manager:1141): WARNING **: failed to get Computer root object

** (gnome-power-manager:1141): WARNING **: proxy NULL!!

(gnome-power-manager:1141): GLib-GObject-WARNING **: value "-nan" of type `gdouble' is invalid or out of range for property `percentage' of type `gdouble'

(gnome-power-manager:1141): GLib-GObject-WARNING **: value "-nan" of type `gdouble' is invalid or out of range for property `percentage' of type `gdouble'

(gnome-power-manager:1141): GLib-GObject-WARNING **: value "-nan" of type `gdouble' is invalid or out of range for property `percentage' of type `gdouble'

(gnome-power-manager:1141): GLib-GObject-WARNING **: value "-nan" of type `gdouble' is invalid or out of range for property `percentage' of type `gdouble'
** (nm-applet:1145): DEBUG: foo_client_state_changed_cb
/usr/lib/pymodules/python2.6/gtk-2.0/gtk/__init__.py:127: RuntimeWarning: PyOS_InputHook is not available for interactive use of PyGTK
  set_interactive(1)
** (nm-applet:1145): DEBUG: foo_client_state_changed_cb

** (gnome-settings-daemon:1125): CRITICAL **: setup_bg: assertion `manager->priv->bg == NULL' failed
evolution-alarm-notify-Message: Setting timeout for 50292 1275775200 1275724908
evolution-alarm-notify-Message: Sun Jun 6 00:00:00 2010

evolution-alarm-notify-Message: Sat Jun 5 10:01:48 2010

** (update-notifier:1443): DEBUG: Skipping reboot required
error: No system tray detected on this system. Unable to start, exiting.

1. however, keybord works, so I am able to switch to tty terminal and from there I am able manually start gnome-panel, nautilus and with DISPLAY=:0.0 <app-name>

2. I checked to ensure, that the file system is ok, by creating/touching a file /forcefsck

[Oedipe (oedipe)]

Very annoying bug ! Seems, and _is_, quite critical ! My screen takes very long time to refresh and sometimes hangs completely. I have exactly the same errors in my output of the xsession-errors file as evgen reported.

[Michael Kogan (michael-kogan)]

I'm experiencing a similar bug: After the update of the 12. December X failed to start, I got a black screen and the keyboard didn't respond. I removed the xorg.conf file (thus changing from the fglrx to the radeon driver) and this resulted in following behavior: still a black screen but with a movable cursor and a working keyboard (however it freezes completely after some time). Creating a clean user didn't change anything. But logging in via a rescue Gnome session worked. I compared the .xsession-errors files from a normal Gnome session and a rescue Gnome session and found the same lines as the original reporter. I attach both .xsession-errors files and the dpkg log of the last updates before the problem appeared.

[Michael Kogan (michael-kogan)]

I want to emphasize that this bug is critical and seems to appear quite common in the past few days. About five users in the German ubuntuusers.de forums have reported this bug already and beside of the rescue mode there seems to be no workaround.

[dj@ngo (saubermann)]

I have installed 10.10 ubuntu new, and the same problem....

..only the rescue mode works ...

[_alex_ (alexkruse)]

after upgrade on my acer extensa 5235 (intel gma4500) to maverick (ubuntu 10.10) same problem

[Bryce Harrington (bryce)]

[Sounds like a GNOME issue rather than X]

[_alex_ (alexkruse)]

update:
after i deactivated the start script for xbacklight (see post http://forum.ubuntuusers.de/topic/bildschirmhelligkeit-am-acer-laptop-einstelle/?highlight=Tbaustell+Zxbacklight+5235#post-2220005 ) i was able to login with normal mode.