Comment 5 for bug 1255800

After another crash, I saw below messages in /var/log/Xorg.0.log.old

[ 42832.431] (EE)
[ 42832.431] (EE) Backtrace:
[ 42832.431] (EE) 0: /usr/bin/X (xorg_backtrace+0x36) [0x7f4ccea5f516]
[ 42832.431] (EE) 1: /usr/bin/X (0x7f4cce8af000+0x1b4359) [0x7f4ccea63359]
[ 42832.431] (EE) 2: /lib/x86_64-linux-gnu/libpthread.so.0 (0x7f4ccd9b2000+0xfbd0) [0x7f4ccd9c1bd0]
[ 42832.431] (EE) 3: /usr/lib/xorg/modules/drivers/intel_drv.so (0x7f4ccb139000+0x3f06c) [0x7f4ccb17806c]
[ 42832.431] (EE) 4: /usr/lib/xorg/modules/drivers/intel_drv.so (0x7f4ccb139000+0x3f7b0) [0x7f4ccb1787b0]
[ 42832.431] (EE) 5: /usr/bin/X (0x7f4cce8af000+0x13a34e) [0x7f4cce9e934e]
[ 42832.431] (EE) 6: /usr/bin/X (0x7f4cce8af000+0x1a09b2) [0x7f4ccea4f9b2]
[ 42832.431] (EE) 7: /usr/bin/X (0x7f4cce8af000+0xe6ab9) [0x7f4cce995ab9]
[ 42832.431] (EE) 8: /usr/bin/X (miSlideAndSizeWindow+0x8a7) [0x7f4ccea584e7]
[ 42832.431] (EE) 9: /usr/bin/X (0x7f4cce8af000+0xe791b) [0x7f4cce99691b]
[ 42832.431] (EE) 10: /usr/bin/X (ConfigureWindow+0xbb0) [0x7f4cce9332b0]
[ 42832.431] (EE) 11: /usr/bin/X (0x7f4cce8af000+0x534a4) [0x7f4cce9024a4]
[ 42832.431] (EE) 12: /usr/bin/X (0x7f4cce8af000+0x58af1) [0x7f4cce907af1]
[ 42832.431] (EE) 13: /usr/bin/X (0x7f4cce8af000+0x475aa) [0x7f4cce8f65aa]
[ 42832.431] (EE) 14: /lib/x86_64-linux-gnu/libc.so.6 (__libc_start_main+0xf5) [0x7f4ccc5fdea5]
[ 42832.431] (EE) 15: /usr/bin/X (0x7f4cce8af000+0x478f1) [0x7f4cce8f68f1]
[ 42832.431] (EE)
[ 42832.431] (EE) Segmentation fault at address 0x80
[ 42832.431]
Fatal server error:
[ 42832.431] Caught signal 11 (Segmentation fault). Server aborting
[ 42832.431]
[ 42832.431] (EE)
Please consult the The X.Org Foundation support
  at http://wiki.x.org
 for help.
[ 42832.431] (EE) Please also check the log file at "/var/log/Xorg.0.log" for additional information.
[ 42832.431] (EE)