Xorg crashed with SIGABRT in _XSERVTransClose()

[Andrea Merli]

After locking screen with CTRL+ALT+L

ProblemType: Crash
DistroRelease: Ubuntu 14.04
Package: xserver-xorg-core 2:1.15.0-1ubuntu7
Uname: Linux 3.13.0-031300-generic i686
NonfreeKernelModules: openafs
ApportVersion: 2.14-0ubuntu1
Architecture: i386
CrashCounter: 1
Date: Thu Apr 3 09:44:54 2014
ExecutablePath: /usr/bin/Xorg
InstallationDate: Installed on 2013-05-09 (328 days ago)
InstallationMedia: Kubuntu 13.04 "Raring Ringtail" - Release i386 (20130424)
ProcCmdline: /usr/bin/X :0 -background none -verbose -auth /var/run/gdm/auth-for-gdm-jFPoR9/database -seat seat0 -nolisten tcp vt7
ProcEnviron:
 LANG=it_IT.UTF-8
 TERM=linux
 PATH=(custom, no user)
Signal: 6
SourcePackage: xorg-server
StacktraceTop:
 ?? ()
 ?? ()
 CloseWellKnownConnections ()
 ?? ()
 FatalError ()
SystemImageInfo: Error: [Errno 2] File o directory non esistente: 'system-image-cli'
Title: Xorg crashed with SIGABRT in CloseWellKnownConnections()
UpgradeStatus: Upgraded to trusty on 2014-03-24 (9 days ago)
UserGroups:

[Apport retracing service (apport)]

StacktraceTop:
 ?? ()
 _XSERVTransClose (ciptr=0xb9488d48) at /usr/include/X11/Xtrans/Xtrans.c:911
 CloseWellKnownConnections () at ../../os/connection.c:515
 AbortServer () at ../../os/log.c:767
 FatalError (f=f@entry=0xb76d04f8 "%s: VT_ACTIVATE failed: %s\n") at ../../os/log.c:911