horizontal line intersected in user mode only

root@gilles-EP31-DS3L:~# lsb_release -rd
Description: Ubuntu 14.04 LTS
Release: 14.04
root@gilles-EP31-DS3L:~# apt-cache policy gdm
gdm:
  Installé : 3.10.0.1-0ubuntu3
  Candidat : 3.10.0.1-0ubuntu3
 Table de version :
 *** 3.10.0.1-0ubuntu3 0
        500 http://fr.archive.ubuntu.com/ubuntu/ trusty/universe amd64 Packages
        100 /var/lib/dpkg/status

After starting the computer, after the "plymouth" screen appears on the full screen horizontal lines intersected, not allowing proper display interface "gnome-shell". This bug only appears in user mode. By stopping gdm service and then starting the startx in console, the display of desktop "gnome-shell" done correctly.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: gdm 3.10.0.1-0ubuntu3
ProcVersionSignature: Ubuntu 3.13.0-24.46-generic 3.13.9
Uname: Linux 3.13.0-24-generic x86_64
ApportVersion: 2.14.1-0ubuntu2
Architecture: amd64
CurrentDesktop: GNOME
Date: Sat Apr 12 09:13:48 2014
InstallationDate: Installed on 2014-04-05 (6 days ago)
InstallationMedia: Ubuntu-GNOME 14.04 LTS "Trusty Tahr" - Beta amd64 (20140326.1)
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 LANG=fr_FR.UTF-8
 SHELL=/bin/bash
SourcePackage: gdm
UpgradeStatus: No upgrade log present (probably fresh install)
mtime.conffile..etc.gdm.custom.conf: 2014-04-05T17:47:31.779135