The same problem appeared when I upgraded from Ubuntu 12.04 to 14:04. I can no longer start Thunderbird.
I get the following when trying to run Thunderbird in terminal: (process:14430): GLib-CRITICAL **: g_slice_set_config: assertion 'sys_page_size == 0' failed (thunderbird:14430): GLib-GObject-WARNING **: Attempt to add property GnomeProgram::sm-connect after class was initialised (thunderbird:14430): GLib-GObject-WARNING **: Attempt to add property GnomeProgram::show-crash-dialog after class was initialised (thunderbird:14430): GLib-GObject-WARNING **: Attempt to add property GnomeProgram::display after class was initialised (thunderbird:14430): GLib-GObject-WARNING **: Attempt to add property GnomeProgram::default-icon after class was initialised [calBackendLoader] Using libical backend at /home/wayne/.thunderbird/s4f56rex.default/extensions/{e2fda1a4-762b-4020-b5ad-a41df1933103}/components/libical.manifest (thunderbird:14430): GLib-GObject-WARNING **: cannot register existing type 'DbusmenuMenuitem' (thunderbird:14430): GLib-CRITICAL **: g_once_init_leave: assertion 'result != 0' failed (thunderbird:14430): GLib-GObject-CRITICAL **: g_param_spec_object: assertion 'g_type_is_a (object_type, G_TYPE_OBJECT)' failed (thunderbird:14430): GLib-GObject-CRITICAL **: g_object_class_install_property: assertion 'G_IS_PARAM_SPEC (pspec)' failed -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1160569 Title: [regression] GLib-CRITICAL **: g_slice_set_config: assertion `sys_page_size == 0' failed To manage notifications about this bug go to: https://bugs.launchpad.net/firefox/+bug/1160569/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs