Ubuntu 12.04 64 bits

Same problem but in my case I don't press ESC nor type a wrong password. Simply I open a new gnome session to another user. When I close (correctly) that session one new lightdm defunct process is created.

Ubuntu 12.04 is a LTS edition. This should be corrected!

By other side, I think this problem provokes another issue: "X11: Maximum number of clients reached"

COMMAND           PID       USER   FD      TYPE             DEVICE   SIZE/OFF       NODE NAME
Xorg            13855       root    1u  unix 0xffff8802c79b5480        0t0     347859 socket
Xorg            13855       root    3u  unix 0xffff8802c79b2700        0t0     347860 /tmp/.X11-unix/X0
Xorg            13855       root   30u  unix 0xffff8802f62afb80        0t0     347868 socket
Xorg            13855       root   31u  unix 0xffff88031cc91d40        0t0     346583 socket
Xorg            13855       root   32u  unix 0xffff88031cc4b400        0t0     348243 socket
Xorg            13855       root   33u  unix 0xffff8802c79b7840        0t0     343941 socket
Xorg            13855       root   34u  unix 0xffff8802d08bd480        0t0  106650780 socket
Xorg            13855       root   35u  unix 0xffff8802c79b6800        0t0     346616 socket
Xorg            13855       root   36u  unix 0xffff8802c79b30c0        0t0     346621 socket
Xorg            13855       root   37u  unix 0xffff8802d08bde40        0t0  106619756 socket
Xorg            13855       root   38u  unix 0xffff88031a1c8340        0t0     349281 socket
Xorg            13855       root   39u  unix 0xffff8802f62abdc0        0t0     349299 socket
Xorg            13855       root   40u  unix 0xffff88031cc9eb40        0t0     349302 socket
Xorg            13855       root   41u  unix 0xffff88002398a3c0        0t0  106653418 socket
Xorg            13855       root   42u  unix 0xffff88031d30bdc0        0t0     314168 socket
Xorg            13855       root   43u  unix 0xffff88031cc49a00        0t0     314173 socket
Xorg            13855       root   44u  unix 0xffff88031a1cdb00        0t0     351343 socket
Xorg            13855       root   45u  unix 0xffff8802c741eb40        0t0     348459 socket
Xorg            13855       root   46u  unix 0xffff88031a1c9380        0t0     346891 socket
Xorg            13855       root   47u  unix 0xffff8802d08b8d00        0t0  106655167 socket
Xorg            13855       root   48u  unix 0xffff88002398fb80        0t0  106651520 socket
Xorg            13855       root   49u  unix 0xffff8803098ff500        0t0     352401 socket
Xorg            13855       root   50u  unix 0xffff8801183c2080        0t0  106652691 socket
Xorg            13855       root   51u  unix 0xffff8802f3322a40        0t0  106653022 socket
Xorg            13855       root   52u  unix 0xffff8802c79b7500        0t0     353514 socket
Xorg            13855       root   54u  unix 0xffff88031cc98000        0t0     349930 socket
Xorg            13855       root   63u  unix 0xffff88031d309380        0t0     488751 socket
Xorg            13855       root   64u  unix 0xffff88002398ad80        0t0     489641 socket

UID        PID  PPID  C STIME TTY      STAT   TIME CMD
root     13855  1815  1 Jan07 tty7     Ss+   16:28 /usr/bin/X :0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
root      1815     1  0 Jan06 ?        00:00:00 lightdm
root     13855  1815  1 Jan07 tty7     00:16:30 /usr/bin/X :0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
root     13930  1815  0 Jan07 ?        00:00:00 lightdm --session-child 12 25
root     31267  1815  0 06:10 ?        00:00:00 [lightdm] <defunct>
root     32625  1815  0 06:53 ?        00:00:00 [lightdm] <defunct>
root     32686  1815  0 06:53 ?        00:00:00 [lightdm] <defunct>