Lightdm fails to display login screen

This problem started after upgrading Ubuntu 12.10 which worked fine to Ubuntu 13.04. After booting, my Dell inspiron 1420 reaches an all purple screen without login. Ctrl-Alt-F1 gives a purple screen with
blinking cursor and the words "starting up" Ctrl-Alt-F2 yields a console terminal where I can access unity with "startx". I needed
to update the Nvidia driver to 319 for "startx" to work.
The /var/log/lightdm/lightdm.log is the following:

[+0.00s] DEBUG: Logging to /var/log/lightdm/lightdm.log
[+0.00s] DEBUG: Starting Light Display Manager 1.6.0, UID=0 PID=11107
[+0.00s] DEBUG: Loaded configuration from /etc/lightdm/lightdm.conf
[+0.00s] DEBUG: Using D-Bus name org.freedesktop.DisplayManager
[+0.00s] DEBUG: Using Xephyr for X servers
[+0.00s] DEBUG: Registered seat module xlocal
[+0.00s] DEBUG: Registered seat module xremote
[+0.00s] DEBUG: Adding default seat
[+0.00s] DEBUG: Starting seat
[+0.00s] DEBUG: Starting new display for greeter
[+0.00s] DEBUG: Starting local X display
[+0.00s] DEBUG: Using VT 7
[+0.00s] DEBUG: Activating VT 7
[+1.88s] DEBUG: Logging to /var/log/lightdm/x-1.log
[+1.88s] DEBUG: Writing X server authority to /var/run/lightdm/root/:1
[+1.88s] DEBUG: Launching X Server
[+1.88s] DEBUG: Launching process 11113: /usr/bin/Xephyr :1 -core -auth /var/run/lightdm/root/:1 -nolisten tcp vt7 -novtswitch
[+1.88s] DEBUG: Waiting for ready signal from X server :1
[+1.88s] DEBUG: Acquired bus name org.freedesktop.DisplayManager
[+1.88s] DEBUG: Registering seat with bus path /org/freedesktop/DisplayManager/Seat0
[+1.93s] DEBUG: Process 11113 exited with return value 1
[+1.93s] DEBUG: X server stopped
[+1.93s] DEBUG: Removing X server authority /var/run/lightdm/root/:1
[+1.93s] DEBUG: Releasing VT 7
[+1.93s] DEBUG: Display server stopped
[+1.93s] DEBUG: Stopping display
[+1.93s] WARNING: Error opening /dev/console: Input/output error
[+1.94s] DEBUG: Stopping seat, failed to start a display
[+1.94s] DEBUG: Stopping seat
[+1.94s] DEBUG: Seat stopped
[+1.94s] DEBUG: Required seat has stopped
[+1.94s] DEBUG: Stopping display manager
[+1.94s] DEBUG: Display manager stopped
[+1.94s] DEBUG: Stopping daemon
[+1.94s] DEBUG: Exiting with return value 1

I have tried reinstalling lightdm, gdm, ubuntu-desktop, and xserver-xorg as well as editing the /etc/init/lightdm.
Occasionally one of these changes has caused the login to work once but break on the following reboot. This
bug is similar but not identical to other reported lightdm bugs. Thank you for your help.

ProblemType: Bug
DistroRelease: Ubuntu 13.04
Package: xorg 1:7.7+1ubuntu4
ProcVersionSignature: Ubuntu 3.8.0-19.30-generic 3.8.8
Uname: Linux 3.8.0-19-generic i686
NonfreeKernelModules: nvidia
.proc.driver.nvidia.gpus.0: Error: [Errno 21] Is a directory: '/proc/driver/nvidia/gpus/0'
.proc.driver.nvidia.registry: Binary: ""
.proc.driver.nvidia.version:
 NVRM version: NVIDIA UNIX x86 Kernel Module 319.12 Wed Apr 3 15:16:16 PDT 2013
 GCC version: gcc version 4.7.3 (Ubuntu/Linaro 4.7.3-1ubuntu1)
.tmp.unity.support.test.0:

ApportVersion: 2.9.2-0ubuntu8
Architecture: i386
CompizPlugins: [core,composite,opengl,compiztoolbox,decor,vpswitch,snap,mousepoll,resize,place,move,wall,grid,regex,imgpng,session,gnomecompat,animation,fade,unitymtgrabhandles,workarounds,scale,expo,ezoom,unityshell]
CompositorRunning: compiz
CompositorUnredirectDriverBlacklist: '(nouveau|Intel).*Mesa 8.0'
CompositorUnredirectFSW: true
Date: Fri May 3 01:08:31 2013
DistUpgraded: 2013-04-25 16:12:56,898 DEBUG enabling apt cron job
DistroCodename: raring
DistroVariant: ubuntu
DkmsStatus: nvidia-319, 319.12, 3.8.0-19-generic, i686: installed
ExtraDebuggingInterest: Yes, if not too technical
GraphicsCard:
 NVIDIA Corporation G86M [GeForce 8400M GS] [10de:0427] (rev a1) (prog-if 00 [VGA controller])
   Subsystem: Dell Device [1028:01f3]
MachineType: Dell Inc. Inspiron 1420
MarkForUpload: True
ProcEnviron:
 TERM=linux
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: root=UUID=b1d3d087-5d6d-426d-b2de-ce481fb598fe ro quiet splash
SourcePackage: xorg
Symptom: display
Title: Xorg crash
UpgradeStatus: Upgraded to raring on 2013-04-25 (7 days ago)
dmi.bios.date: 12/19/2008
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A10
dmi.board.name: 0Y918J
dmi.board.vendor: Dell Inc.
dmi.chassis.type: 8
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvrA10:bd12/19/2008:svnDellInc.:pnInspiron1420:pvr:rvnDellInc.:rn0Y918J:rvr:cvnDellInc.:ct8:cvr:
dmi.product.name: Inspiron 1420
dmi.sys.vendor: Dell Inc.
version.compiz: compiz 1:0.9.9~daily13.04.18.1~13.04-0ubuntu1
version.libdrm2: libdrm2 2.4.44+git20130502.01199992-0ubuntu0sarvatt
version.libgl1-mesa-dri: libgl1-mesa-dri 9.2.0~git20130502.156bcca6-0ubuntu0sarvatt
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 9.2.0~git20130502.156bcca6-0ubuntu0sarvatt
version.nvidia-graphics-drivers: nvidia-graphics-drivers N/A
version.xserver-xorg-core: xserver-xorg-core 2:1.13.3-0ubuntu6
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.7.3-0ubuntu2b2
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.1.99+git20130315.3e5350be-0ubuntu0sarvatt
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.21.6+git20130502.5637c173-0ubuntu0sarvatt
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.7-0ubuntu1
xserver.bootTime: Thu May 2 22:53:43 2013
xserver.configfile: /etc/X11/xorg.conf
xserver.errors:

xserver.logfile: /var/log/Xorg.0.log
xserver.outputs:

xserver.version: 2:1.13.3-0ubuntu6