Comment 4 for bug 672206

I had this issue right now too. I attached the process using gdb.

Attaching to process 1775
Reading symbols from /usr/lib/indicator-application/indicator-application-service...(no debugging symbols found)...done.
Reading symbols from /usr/lib/libindicator.so.1...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libindicator.so.1
Reading symbols from /usr/lib/libgtk-x11-2.0.so.0...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libgtk-x11-2.0.so.0
Reading symbols from /usr/lib/libgdk-x11-2.0.so.0...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libgdk-x11-2.0.so.0
Reading symbols from /usr/lib/libatk-1.0.so.0...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libatk-1.0.so.0
Reading symbols from /usr/lib/libgio-2.0.so.0...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libgio-2.0.so.0
Reading symbols from /usr/lib/libpangoft2-1.0.so.0...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libpangoft2-1.0.so.0
Reading symbols from /usr/lib/libpangocairo-1.0.so.0...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libpangocairo-1.0.so.0
Reading symbols from /usr/lib/libgdk_pixbuf-2.0.so.0...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libgdk_pixbuf-2.0.so.0
Reading symbols from /lib/libm.so.6...(no debugging symbols found)...done.
Loaded symbols for /lib/libm.so.6
Reading symbols from /usr/lib/libcairo.so.2...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libcairo.so.2
Reading symbols from /lib/libpng12.so.0...(no debugging symbols found)...done.
Loaded symbols for /lib/libpng12.so.0
Reading symbols from /usr/lib/libpango-1.0.so.0...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libpango-1.0.so.0
Reading symbols from /usr/lib/libfreetype.so.6...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libfreetype.so.6
Reading symbols from /usr/lib/libfontconfig.so.1...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libfontconfig.so.1
Reading symbols from /usr/lib/libgmodule-2.0.so.0...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libgmodule-2.0.so.0
Reading symbols from /usr/lib/libjson-glib-1.0.so.0...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libjson-glib-1.0.so.0
Reading symbols from /usr/lib/libdbusmenu-gtk.so.1...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libdbusmenu-gtk.so.1
Reading symbols from /usr/lib/libdbusmenu-glib.so.1...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libdbusmenu-glib.so.1
Reading symbols from /usr/lib/libdbus-glib-1.so.2...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libdbus-glib-1.so.2
Reading symbols from /lib/libdbus-1.so.3...(no debugging symbols found)...done.
Loaded symbols for /lib/libdbus-1.so.3
Reading symbols from /lib/libpthread.so.0...(no debugging symbols found)...done.
[Thread debugging using libthread_db enabled]
Loaded symbols for /lib/libpthread.so.0
Reading symbols from /usr/lib/libgobject-2.0.so.0...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libgobject-2.0.so.0
Reading symbols from /usr/lib/libgthread-2.0.so.0...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libgthread-2.0.so.0
Reading symbols from /lib/librt.so.1...(no debugging symbols found)...done.
Loaded symbols for /lib/librt.so.1
Reading symbols from /lib/libglib-2.0.so.0...(no debugging symbols found)...done.
Loaded symbols for /lib/libglib-2.0.so.0
Reading symbols from /usr/lib/libappindicator.so.1...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libappindicator.so.1
Reading symbols from /lib/libc.so.6...(no debugging symbols found)...done.
Loaded symbols for /lib/libc.so.6
Reading symbols from /usr/lib/libXext.so.6...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libXext.so.6
Reading symbols from /usr/lib/libXrender.so.1...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libXrender.so.1
Reading symbols from /usr/lib/libXinerama.so.1...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libXinerama.so.1
Reading symbols from /usr/lib/libXi.so.6...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libXi.so.6
Reading symbols from /usr/lib/libXrandr.so.2...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libXrandr.so.2
Reading symbols from /usr/lib/libXcursor.so.1...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libXcursor.so.1
Reading symbols from /usr/lib/libX11.so.6...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libX11.so.6
Reading symbols from /usr/lib/libXcomposite.so.1...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libXcomposite.so.1
Reading symbols from /usr/lib/libXdamage.so.1...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libXdamage.so.1
Reading symbols from /usr/lib/libXfixes.so.3...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libXfixes.so.3
Reading symbols from /lib/libz.so.1...(no debugging symbols found)...done.
Loaded symbols for /lib/libz.so.1
Reading symbols from /lib/libdl.so.2...(no debugging symbols found)...done.
Loaded symbols for /lib/libdl.so.2
Reading symbols from /lib/libpcre.so.3...(no debugging symbols found)...done.
Loaded symbols for /lib/libpcre.so.3
Reading symbols from /lib/libresolv.so.2...(no debugging symbols found)...done.
Loaded symbols for /lib/libresolv.so.2
Reading symbols from /lib/libselinux.so.1...(no debugging symbols found)...done.
Loaded symbols for /lib/libselinux.so.1
Reading symbols from /lib/ld-linux.so.2...(no debugging symbols found)...done.
Loaded symbols for /lib/ld-linux.so.2
Reading symbols from /usr/lib/libpixman-1.so.0...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libpixman-1.so.0
Reading symbols from /usr/lib/libxcb-shm.so.0...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libxcb-shm.so.0
Reading symbols from /usr/lib/libxcb-render.so.0...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libxcb-render.so.0
Reading symbols from /usr/lib/libxcb.so.1...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libxcb.so.1
Reading symbols from /lib/libexpat.so.1...(no debugging symbols found)...done.
Loaded symbols for /lib/libexpat.so.1
Reading symbols from /usr/lib/libxml2.so.2...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libxml2.so.2
Reading symbols from /usr/lib/libXau.so.6...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libXau.so.6
Reading symbols from /usr/lib/libXdmcp.so.6...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libXdmcp.so.6
Reading symbols from /lib/libnss_compat.so.2...(no debugging symbols found)...done.
Loaded symbols for /lib/libnss_compat.so.2
Reading symbols from /lib/libnsl.so.1...(no debugging symbols found)...done.
Loaded symbols for /lib/libnsl.so.1
Reading symbols from /lib/libnss_nis.so.2...(no debugging symbols found)...done.
Loaded symbols for /lib/libnss_nis.so.2
Reading symbols from /lib/libnss_files.so.2...(no debugging symbols found)...done.
Loaded symbols for /lib/libnss_files.so.2
0x00f3a990 in _IO_default_xsputn () from /lib/libc.so.6

backtrace

#0 0x00c9b91a in g_string_free () from /lib/libglib-2.0.so.0
#1 0x00c80c61 in g_log_default_handler () from /lib/libglib-2.0.so.0
#2 0x00c810eb in g_logv () from /lib/libglib-2.0.so.0
#3 0x00c81572 in g_log () from /lib/libglib-2.0.so.0
#4 0x00c8179d in g_return_if_fail_warning () from /lib/libglib-2.0.so.0
#5 0x0804b9ac in ?? ()
#6 0x00c0558b in g_object_unref () from /usr/lib/libgobject-2.0.so.0
#7 0x08049d51 in ?? ()
#8 0x00ee6ce7 in __libc_start_main () from /lib/libc.so.6
#9 0x08049be1 in ?? ()

then i attached strace:
...
[00439416] write(2, "\n(process:1775): indicator-application-service-CRITICAL **: application_service_appstore_application_remove: assertion `dbus_object != NULL && dbus_object[0] != '\\0'' failed\n", 174) = 174
[00439416] write(2, "\n(process:1775): indicator-application-service-CRITICAL **: application_service_appstore_application_remove: assertion `dbus_object != NULL && dbus_object[0] != '\\0'' failed\n", 174) = 174
[00439416] write(2, "\n(process:1775): indicator-application-service-CRITICAL **: application_service_appstore_application_remove: assertion `dbus_object != NULL && dbus_object[0] != '\\0'' failed\n", 174) = 174
[00439416] write(2, "\n(process:1775): indicator-application-service-CRITICAL **: application_service_appstore_application_remove: assertion `dbus_object != NULL && dbus_object[0] != '\\0'' failed\n", 174) = 174
[00439416] write(2, "\n(process:1775): indicator-application-service-CRITICAL **: application_service_appstore_application_remove: assertion `dbus_object != NULL && dbus_object[0] != '\\0'' failed\n", 174) = 174
....
....
and so on and so on

According to the gnome system monitor file descriptor 2 has /dev/null open.
The process can simply be stopped from rioting by sending SIGTERM.