system locks/freezes up after some time idle

[Manuel López-Ibáñez]

After leaving the computer connected to an external monitor and unattended a few minutes, the system locks up.

The only recourse is to reboot with Alt+SysRq+B.

Switching terminals or disconneting the external monitor does not work.

syslog/dmesg don't contain any interesting event before freezing up. However, Xorg.log says:

[ 23368.997] [mi] EQ overflowing. Additional events will be discarded until existing events are processed.
[ 23368.997]
Backtrace:
[ 23369.063] 0: /usr/bin/X (xorg_backtrace+0x37) [0xb76ae7a7]
[ 23369.064] 1: /usr/bin/X (mieqEnqueue+0x223) [0xb768caf3]
[ 23369.064] 2: /usr/bin/X (0xb7526000+0x4ccd5) [0xb7572cd5]
[ 23369.064] 3: /usr/bin/X (xf86PostMotionEventM+0xf9) [0xb75b3d99]
[ 23369.064] 4: /usr/lib/xorg/modules/input/evdev_drv.so (0xaffce000+0x3c3d) [0xaffd1c3d]
[ 23369.064] 5: /usr/lib/xorg/modules/input/evdev_drv.so (0xaffce000+0x524f) [0xaffd324f]
[ 23369.064] 6: /usr/bin/X (0xb7526000+0x78381) [0xb759e381]
[ 23369.064] 7: /usr/bin/X (0xb7526000+0x9fce8) [0xb75c5ce8]
[ 23369.064] 8: (vdso) (__kernel_sigreturn+0x0) [0xb7503400]
[ 23369.064] 9: (vdso) (__kernel_vsyscall+0x10) [0xb7503424]
[ 23369.065] 10: /lib/i386-linux-gnu/libc.so.6 (ioctl+0x19) [0xb724cb79]
[ 23369.065] 11: /usr/lib/dri/fglrx_dri.so (0xaffde000+0x1c76ea9) [0xb1c54ea9]
[ 23369.065] [mi] These backtraces from mieqEnqueue may point to a culprit higher up the stack.
[ 23369.065] [mi] mieq is *NOT* the cause. It is a victim.
[ 23369.477] [mi] EQ overflow continuing. 100 events have been dropped.
[ 23369.477]
Backtrace:
[ 23369.477] 0: /usr/bin/X (xorg_backtrace+0x37) [0xb76ae7a7]
[ 23369.477] 1: /usr/bin/X (mieqEnqueue+0xf8) [0xb768c9c8]
[ 23369.477] 2: /usr/bin/X (0xb7526000+0x4ccd5) [0xb7572cd5]
[ 23369.477] 3: /usr/bin/X (xf86PostMotionEventM+0xf9) [0xb75b3d99]
[ 23369.477] 4: /usr/lib/xorg/modules/input/evdev_drv.so (0xaffce000+0x3c3d) [0xaffd1c3d]
[ 23369.477] 5: /usr/lib/xorg/modules/input/evdev_drv.so (0xaffce000+0x524f) [0xaffd324f]
[ 23369.477] 6: /usr/bin/X (0xb7526000+0x78381) [0xb759e381]
[ 23369.477] 7: /usr/bin/X (0xb7526000+0x9fce8) [0xb75c5ce8]
[ 23369.477] 8: (vdso) (__kernel_sigreturn+0x0) [0xb7503400]
[ 23369.478] 9: (vdso) (__kernel_vsyscall+0x10) [0xb7503424]
[ 23369.478] 10: /lib/i386-linux-gnu/libc.so.6 (ioctl+0x19) [0xb724cb79]
[ 23369.478] 11: /usr/lib/dri/fglrx_dri.so (0xaffde000+0x1c76ea9) [0xb1c54ea9]
[ 23391.968] [mi] EQ overflow continuing. 200 events have been dropped.
[ 23391.968]
Backtrace:
[ 23391.968] 0: /usr/bin/X (xorg_backtrace+0x37) [0xb76ae7a7]
[ 23391.968] 1: /usr/bin/X (mieqEnqueue+0xf8) [0xb768c9c8]
[ 23391.968] 2: /usr/bin/X (0xb7526000+0x4ccd5) [0xb7572cd5]
[ 23391.969] 3: /usr/bin/X (xf86PostKeyEventM+0x8e) [0xb75b45de]
[ 23391.969] 4: /usr/bin/X (xf86PostKeyboardEvent+0x72) [0xb75b4882]
[ 23391.969] 5: /usr/lib/xorg/modules/input/evdev_drv.so (0xaffce000+0x52b5) [0xaffd32b5]
[ 23391.969] 6: /usr/bin/X (0xb7526000+0x78381) [0xb759e381]
[ 23391.969] 7: /usr/bin/X (0xb7526000+0x9fce8) [0xb75c5ce8]
[ 23391.969] 8: (vdso) (__kernel_sigreturn+0x0) [0xb7503400]
[ 23391.969] 9: (vdso) (__kernel_vsyscall+0x10) [0xb7503424]
[ 23391.969] 10: /lib/i386-linux-gnu/libc.so.6 (ioctl+0x19) [0xb724cb79]
[ 23391.969] 11: /usr/lib/dri/fglrx_dri.so (0xaffde000+0x1c76ea9) [0xb1c54ea9]

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: fglrx 2:8.960-0ubuntu1.1
ProcVersionSignature: Ubuntu 3.2.0-48.74-generic-pae 3.2.46
Uname: Linux 3.2.0-48-generic-pae i686
NonfreeKernelModules: fglrx
ApportVersion: 2.0.1-0ubuntu17.3
Architecture: i386
Date: Thu Jul 4 16:19:26 2013
EcryptfsInUse: Yes
InstallationMedia: Kubuntu 12.04 LTS "Precise Pangolin" - Release i386 (20120423)
MarkForUpload: True
SourcePackage: fglrx-installer
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

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