Adding debug backtrace:

--- stack trace ---
Using host libthread_db library "/lib/tls/i686/cmov/libthread_db.so.1".
Core was generated by `/usr/lib/notification-daemon/notification-daemon'.
Program terminated with signal 11, Segmentation fault.
#0  0xb7f0d6cc in dbus_g_method_return_error (context=0x0, error=0x8250dcc) at dbus-gobject.c:1996
1996    {
#0  0xb7f0d6cc in dbus_g_method_return_error (context=0x0, error=0x8250dcc) at dbus-gobject.c:1996
        reply = (DBusMessage *) 0x80554b0
#1  0xb792d53e in IA__g_slist_find_custom (list=0x80973e0, data=0x8250dcc, func=0xb7f0d6b0 <dbus_g_method_return+782>)
    at gslist.c:389
        __PRETTY_FUNCTION__ = "IA__g_slist_find_custom"
#2  0xb7f11acc in dbus_g_proxy_set_interface (proxy=0x807cd40, interface_name=0x807c8c0 "\001") at dbus-gproxy.c:2036
        priv = (DBusGProxyPrivate *) 0x0
#3  0xb7ede8ce in dbus_connection_send (connection=0x807cd40, message=0x807e6d8, client_serial=0xbfffd238) at dbus-connection.c:2349
        __FUNCTION__ = "a\000dbus_timeout_set_da"
#4  0xb7f0951d in watch_toggled (watch=0x807e6d8, data=0x0) at dbus-gmain.c:455
No locals.
#5  0xb7915802 in IA__g_main_context_dispatch (context=0x8074118) at gmain.c:2045
No locals.
#6  0xb79187df in g_main_context_iterate (context=0x8074118, block=1, dispatch=1, self=0x8075348) at gmain.c:2677
        got_ownership = <value optimized out>
        max_priority = 0
        timeout = 0
        some_ready = 1
        nfds = <value optimized out>
        allocated_nfds = <value optimized out>
        fds = (GPollFD *) 0x80800a0
        __PRETTY_FUNCTION__ = "g_main_context_iterate"
#7  0xb7918b89 in IA__g_main_loop_run (loop=0x807f420) at gmain.c:2881
        got_ownership = -1215437856
        self = (GThread *) 0x8075348
        __PRETTY_FUNCTION__ = "IA__g_main_loop_run"
#8  0xb7c55574 in IA__gtk_main () at gtkmain.c:1024
        tmp_list = (GList *) 0x0
        functions = (GList *) 0x0
        init = (GtkInitFunction *) 0xbfffd3b8
        loop = (GMainLoop *) 0x807f420
#9  0x0804ca3b in main (argc=11259375, argv=0xabcdef) at daemon.c:1159
        connection = (DBusGConnection *) 0x807cd44
        bus_proxy = <value optimized out>
        error = (GError *) 0x0
        request_name_result = 1
#10 0xb77b88cc in __libc_start_main () from /lib/tls/i686/cmov/libc.so.6
No symbol table info available.
#11 0x0804a2a1 in _start ()
No symbol table info available.
--- thread stack trace ---
Using host libthread_db library "/lib/tls/i686/cmov/libthread_db.so.1".
Core was generated by `/usr/lib/notification-daemon/notification-daemon'.
Program terminated with signal 11, Segmentation fault.
#0  0xb7f0d6cc in dbus_g_method_return_error (context=0x0, error=0x8250dcc) at dbus-gobject.c:1996
1996    {
.
Thread 1 (process 5737):
#0  0xb7f0d6cc in dbus_g_method_return_error (context=0x0, error=0x8250dcc) at dbus-gobject.c:1996
        reply = (DBusMessage *) 0x80554b0
#1  0xb792d53e in IA__g_slist_find_custom (list=0x80973e0, data=0x8250dcc, func=0xb7f0d6b0 <dbus_g_method_return+782>)
    at gslist.c:389
        __PRETTY_FUNCTION__ = "IA__g_slist_find_custom"
#2  0xb7f11acc in dbus_g_proxy_set_interface (proxy=0x807cd40, interface_name=0x807c8c0 "\001") at dbus-gproxy.c:2036
        priv = (DBusGProxyPrivate *) 0x0
#3  0xb7ede8ce in dbus_connection_send (connection=0x807cd40, message=0x807e6d8, client_serial=0xbfffd238) at dbus-connection.c:2349
        __FUNCTION__ = "a\000dbus_timeout_set_da"
#4  0xb7f0951d in watch_toggled (watch=0x807e6d8, data=0x0) at dbus-gmain.c:455
No locals.
#5  0xb7915802 in IA__g_main_context_dispatch (context=0x8074118) at gmain.c:2045
No locals.
#6  0xb79187df in g_main_context_iterate (context=0x8074118, block=1, dispatch=1, self=0x8075348) at gmain.c:2677
        got_ownership = <value optimized out>
        max_priority = 0
        timeout = 0
        some_ready = 1
        nfds = <value optimized out>
        allocated_nfds = <value optimized out>
        fds = (GPollFD *) 0x80800a0
        __PRETTY_FUNCTION__ = "g_main_context_iterate"
#7  0xb7918b89 in IA__g_main_loop_run (loop=0x807f420) at gmain.c:2881
        got_ownership = -1215437856
        self = (GThread *) 0x8075348
        __PRETTY_FUNCTION__ = "IA__g_main_loop_run"
#8  0xb7c55574 in IA__gtk_main () at gtkmain.c:1024
        tmp_list = (GList *) 0x0
        functions = (GList *) 0x0
        init = (GtkInitFunction *) 0xbfffd3b8
        loop = (GMainLoop *) 0x807f420
#9  0x0804ca3b in main (argc=11259375, argv=0xabcdef) at daemon.c:1159
        connection = (DBusGConnection *) 0x807cd44
        bus_proxy = <value optimized out>
        error = (GError *) 0x0
        request_name_result = 1
#10 0xb77b88cc in __libc_start_main () from /lib/tls/i686/cmov/libc.so.6
No symbol table info available.
#11 0x0804a2a1 in _start ()
No symbol table info available.