Lots of nautilus errors

[Michael Heuberger]

$ cat /var/log/syslog shows me lots of nautilus-related errors. My system is behaving weird lately since the upgrade from Ubuntu 14.10 to 15.04 so I am guessing this might be related. Alright, here the relevant log entries:

Aug 19 19:56:24 M1 gnome-session[25925]: (nautilus:29366): Gtk-CRITICAL **: gtk_icon_theme_get_for_screen: assertion 'GDK_IS_SCREEN (screen)' failed
Aug 19 19:56:24 M1 gnome-session[25925]: (nautilus:29366): GLib-GObject-WARNING **: invalid (NULL) pointer instance
Aug 19 19:56:24 M1 gnome-session[25925]: (nautilus:29366): GLib-GObject-CRITICAL **: g_signal_connect_object: assertion 'G_TYPE_CHECK_INSTANCE (instance)' failed
...
Aug 19 20:25:11 M1 org.freedesktop.FileManager1[25838]: message repeated 4 times: [ ** (nautilus:26119): CRITICAL **: nautilus_menu_provider_get_background_items: assertion 'NAUTILUS_IS_MENU_PROVIDER (provider)' failed]
Aug 19 20:25:22 M1 org.freedesktop.FileManager1[25838]: ** (nautilus:26119): CRITICAL **: nautilus_menu_provider_get_background_items: assertion 'NAUTILUS_IS_MENU_PROVIDER (provider)' failed

Any ideas what this could be?