Firefox error critical?

Hi all,

when starting firefox from terminal, the output given is

$ firefox

(process:3083): GLib-CRITICAL **: g_slice_set_config: assertion `sys_page_size == 0' failed
Running global cleanup code from study base classes.

Firefox version is 23.0; kernel version is 3.8.0-19-generic #30-Ubuntu SMP Wed May 1 16:35:23 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux; OS installed is XUbuntu 13.04.

This glib error can also be found in .xsession-errors:

$ more .xsession-errors

openConnection: connect: Datei oder Verzeichnis nicht gefunden
cannot connect to brltty at :0
Skript für cjkv unter run_im gestartet.
Skript für default unter run_im gestartet.
Skript für cjkv unter run_im gestartet.
Skript für default unter run_im gestartet.
xrdb: "Xft.hinting" on line 13 overrides entry on line 6
xrdb: "Xft.hintstyle" on line 14 overrides entry on line 7

(xfdesktop:2423): GLib-GIO-CRITICAL **: g_file_get_path: assertion `G_IS_FILE (f
ile)' failed

(xfdesktop:2423): GLib-GIO-CRITICAL **: g_file_get_path: assertion `G_IS_FILE (f
ile)' failed

(xfdesktop:2423): GLib-GIO-CRITICAL **: g_file_get_path: assertion `G_IS_FILE (f
ile)' failed

(polkit-gnome-authentication-agent-1:2509): GLib-CRITICAL **: g_variant_new_stri
ng: assertion `string != NULL' failed

(polkit-gnome-authentication-agent-1:2509): polkit-gnome-1-WARNING **: Failed to
 register client: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The nam
e org.gnome.SessionManager was not provided by any .service files

** (gnome-settings-daemon:2488): WARNING **: You can only run one xsettings mana
ger at a time; exiting

** (gnome-settings-daemon:2488): WARNING **: Unable to start xsettings manager:
Could not initialize xsettings manager.

** (gnome-settings-daemon:2488): WARNING **: Unable to register client: GDBus.Er
ror:org.freedesktop.DBus.Error.ServiceUnknown: The name org.gnome.SessionManager
 was not provided by any .service files

(gnome-settings-daemon:2488): power-plugin-WARNING **: IsInhibited failed: GDBus
.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name org.gnome.SessionMana
ger was not provided by any .service files
** Message: applet now removed from the notification area

(gnome-settings-daemon:2488): clipboard-plugin-WARNING **: Clipboard manager is
already running.

** (process:2831): WARNING **: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnk
nown: The name org.gnome.SessionManager was not provided by any .service files
xfdesktop: Fatal IO error 11 (Die Ressource ist zur Zeit nicht verfügbar) on X s
erver :0.0.
** Message: using fallback from indicator to GtkStatusIcon
** Message: applet now embedded in the notification area

(update-notifier:2498): GLib-GObject-CRITICAL **: g_object_get_data: assertion `
G_IS_OBJECT (object)' failed

(xfdesktop:2837): GLib-GIO-CRITICAL **: g_file_get_path: assertion `G_IS_FILE (f
ile)' failed

(xfdesktop:2837): GLib-GIO-CRITICAL **: g_file_get_path: assertion `G_IS_FILE (f
ile)' failed

(xfdesktop:2837): GLib-GIO-CRITICAL **: g_file_get_path: assertion `G_IS_FILE (f
ile)' failed

(process:2856): GLib-CRITICAL **: g_slice_set_config: assertion `sys_page_size =
= 0' failed
Error: No running window found

(process:2860): GLib-CRITICAL **: g_slice_set_config: assertion `sys_page_size =
= 0' failed

(xfce4-terminal:2425): Gdk-CRITICAL **: IA__gdk_window_get_window_type: assertio
n `GDK_IS_WINDOW (window)' failed

(process:3182): GLib-CRITICAL **: g_slice_set_config: assertion `sys_page_size =
= 0' failed
Error: No running window found

(process:3186): GLib-CRITICAL **: g_slice_set_config: assertion `sys_page_size =
= 0' failed

(process:3262): GLib-CRITICAL **: g_slice_set_config: assertion `sys_page_size =
= 0' failed

Is this a GLib bug or do I have to fix my user account? If so, how?

Can someone please give me advice?

Kind regards,

Stefan