Not sure if the attached backtrace helps.

(unity-panel-service:4787): GLib-GObject-WARNING **: g_object_weak_unref: couldn't find weak ref 0x7ffe37df60b0(0x119d070)
^C
(unity-panel-service:4787): IDO-WARNING **: Can't load user avatar icon: Error opening file: No such file or directory

(gdb) thread apply all backtrace

Thread 3 (Thread 0x7ffe3d661700 (LWP 4788)):
#0  0x00007ffe44bc347d in poll () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007ffe4598f694 in g_main_context_poll (priority=2147483647, n_fds=3, fds=0x7ffe380010e0, timeout=-1, context=0x103e8a0) at /build/buildd/glib2.0-2.38.0/./glib/gmain.c:4006
#2  g_main_context_iterate (context=0x103e8a0, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimised out>) at /build/buildd/glib2.0-2.38.0/./glib/gmain.c:3707
#3  0x00007ffe4598fafa in g_main_loop_run (loop=0x103e830) at /build/buildd/glib2.0-2.38.0/./glib/gmain.c:3906
#4  0x00007ffe461849d6 in gdbus_shared_thread_func (user_data=0x103e870) at /build/buildd/glib2.0-2.38.0/./gio/gdbusprivate.c:278
#5  0x00007ffe459b40e5 in g_thread_proxy (data=0x10278f0) at /build/buildd/glib2.0-2.38.0/./glib/gthread.c:798
#6  0x00007ffe44ea4f6e in start_thread (arg=0x7ffe3d661700) at pthread_create.c:311
#7  0x00007ffe44bcfecd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113

Thread 2 (Thread 0x7ffe3ca4f700 (LWP 4789)):
#0  0x00007ffe44bc347d in poll () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007ffe4598f694 in g_main_context_poll (priority=2147483647, n_fds=1, fds=0x7ffe300010c0, timeout=-1, context=0x1082400) at /build/buildd/glib2.0-2.38.0/./glib/gmain.c:4006
#2  g_main_context_iterate (context=context@entry=0x1082400, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimised out>) at /build/buildd/glib2.0-2.38.0/./glib/gmain.c:3707
#3  0x00007ffe4598f79c in g_main_context_iteration (context=0x1082400, may_block=1) at /build/buildd/glib2.0-2.38.0/./glib/gmain.c:3773
#4  0x00007ffe3ca56a9d in ?? () from /usr/lib/x86_64-linux-gnu/gio/modules/libdconfsettings.so
#5  0x00007ffe459b40e5 in g_thread_proxy (data=0x118bb20) at /build/buildd/glib2.0-2.38.0/./glib/gthread.c:798
#6  0x00007ffe44ea4f6e in start_thread (arg=0x7ffe3ca4f700) at pthread_create.c:311
#7  0x00007ffe44bcfecd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113

Thread 1 (Thread 0x7ffe47b2d980 (LWP 4787)):
#0  0x00007ffe44bc347d in poll () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007ffe4598f694 in g_main_context_poll (priority=2147483647, n_fds=3, fds=0x11980d0, timeout=28477, context=0x104bde0) at /build/buildd/glib2.0-2.38.0/./glib/gmain.c:4006
#2  g_main_context_iterate (context=0x104bde0, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimised out>) at /build/buildd/glib2.0-2.38.0/./glib/gmain.c:3707
#3  0x00007ffe4598fafa in g_main_loop_run (loop=0x11980b0) at /build/buildd/glib2.0-2.38.0/./glib/gmain.c:3906
#4  0x00007ffe46a5e455 in gtk_main () from /usr/lib/x86_64-linux-gnu/libgtk-3.so.0
#5  0x0000000000404e57 in main (argc=1, argv=0x7ffff8f0bb98) at /build/buildd/unity-7.1.2+13.10.20131011/services/panel-main.c:418
(gdb) quit
A debugging session is active.

        Inferior 1 [process 4787] will be detached.

Quit anyway? (y or n) y
Detaching from program: /usr/lib/unity/unity-panel-service, process 4787