14.04 unity-greeter crash

[frère Régis Grosperrin aa]

After asking a question#253677, i was answered to report a bug.
Could be similar to bug #851319 or #851842

No similar problem with 12.04.

I can log in; then with the desktop appears this message: "System program problem detected".
This appears each time.
Otherwise, i can use the OS without pb.

See the details below.

I can't open the crash report with apport:
regis@lifebook:~$ apport-retrace --gdb /var/crash/_usr_sbin_unity-greeter.104.crash
ERROR: Cannot open report file: [Errno 13] Permission denied: '/var/crash/_usr_sbin_unity-greeter.104.crash'

details:
executable path
/usr/sbin/unity-greeter

ProblemType
Crash

Architecture
i386

CoreDump
CrashCounter
1

Date (it appears each time i am logging in)

DistroRelease
Ubuntu 14.04

ProcCmdLine
/usr/lib/unity-greeter

ProcCmd
/var/lib/lightdm

ProcCEnviron
PATH=(custom, nouser)
XDG_RUNTIME_DIR=<set>
LANG=fr_FR.UTF-8
SHELL=/bin/false

ProcMap

ProcStatus

Signal
6

Uname
linux 3.13.0-34-generic i686

UnreportableReason
EOFError ('Compressed file ended before the end-of-stream marker was reached')

UserGroups

same problem also for other languages:
LANG=ja_JP.UTF-8

[n6ilvu0cwman (n6ilvu0cwman)]

same problem also for other languages:
LANG=ja_JP.UTF-8

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Fabounet (fabounet03)]

Same here, on an up-to-date 14.04.
The bug report can't be sent, and using apport-retrace from a terminal I get:
> apport-retrace --gdb /var/crash/_usr_sbin_unity-greeter.1002.crash
ERROR: report file does not contain one of the required fields: CoreDump DistroRelease Package ExecutablePath

it's not critical since I can log-in, but still is annoying because of the popup (and may hide a more serious problem).