This is probably a dupe of bug #982889. Try adding sleep to your lightdm.conf as described in that bug and see if it works around the issue.
** Description changed: Xorg sometimes don't start at boot. - #2 0x00007f7ea445f2ae in OsAbort () - #3 0x00007f7ea4464223 in ?? () - #4 0x00007f7ea4464a9d in FatalError () - #5 0x00007f7ea42f07d2 in ?? () - #6 0x00007f7ea1ff9ea5 in __libc_start_main (main=0x7f7ea42f0110, argc=9, ubp_av=0x7fffea6a6a58, - init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, - stack_end=0x7fffea6a6a48) at libc-start.c:260 - unwind_buf = {cancel_jmp_buf = {{jmp_buf = {0, 4991247855042815178, 140181897152504, - 140737126230608, 0, 0, -4991204797383056182, -4919836772781005622}, - mask_was_saved = 0}}, priv = {pad = {0x0, 0x0, 0x7f7ea4468370 <__libc_csu_init>, - 0x7fffea6a6a58}, data = {prev = 0x0, cleanup = 0x0, canceltype = -1538882704}}} - #7 0x00007f7ea42f0821 in _start () + #4 0x00007f7ea4464a9d in FatalError (f=f@entry=0x7f7ea4468442 "no screens found") + at ../../os/log.c:793 + args = {{gp_offset = 8, fp_offset = 48, overflow_arg_area = 0x7fffea6a6910, + reg_save_area = 0x7fffea6a6850}} + args2 = {{gp_offset = 8, fp_offset = 48, overflow_arg_area = 0x7fffea6a6910, + reg_save_area = 0x7fffea6a6850}} + beenhere = 1 + #5 0x00007f7ea42f07d2 in main (argc=9, argv=0x7fffea6a6a58, envp=<optimized out>) + at ../../dix/main.c:207 + alwaysCheckForInput = {0, 1} + ProblemType: Crash DistroRelease: Ubuntu 13.04 Package: xserver-xorg-core 2:1.13.3-0ubuntu4 ProcVersionSignature: Ubuntu 3.8.0-16.26-generic 3.8.5 Uname: Linux 3.8.0-16-generic x86_64 .tmp.unity.support.test.0: ApportVersion: 2.9.2-0ubuntu5 Architecture: amd64 CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins' CompositorRunning: compiz CompositorUnredirectDriverBlacklist: '(nouveau|Intel).*Mesa 8.0' CompositorUnredirectFSW: true CrashCounter: 1 Date: Fri Apr 5 13:24:41 2013 DistUpgraded: 2013-03-19 00:10:58,994 DEBUG enabling apt cron job DistroCodename: raring DistroVariant: ubuntu DkmsStatus: virtualbox, 4.2.10: added ExecutablePath: /usr/bin/Xorg GraphicsCard: Advanced Micro Devices [AMD] nee ATI Juniper XT [AMD Radeon HD 6000 Series] [1002:68ba] (prog-if 00 [VGA controller]) Subsystem: ASUSTeK Computer Inc. Device [1043:040b] InstallationDate: Installed on 2013-02-07 (57 days ago) InstallationMedia: Ubuntu 12.10 "Quantal Quetzal" - Release amd64 (20121017.5) MachineType: System manufacturer System Product Name MarkForUpload: True ProcCmdline: /usr/bin/X :0 -core -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch ProcEnviron: ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.8.0-16-generic root=UUID=5f72727e-ae34-4862-9f87-af6ca6d14636 ro quiet splash vt.handoff=7 Signal: 6 SourcePackage: xorg-server StacktraceTop: raise () from /lib/x86_64-linux-gnu/libc.so.6 abort () from /lib/x86_64-linux-gnu/libc.so.6 OsAbort () ?? () FatalError () Title: Xorg crashed with SIGABRT in raise() UpgradeStatus: Upgraded to raring on 2013-03-18 (18 days ago) UserGroups: dmi.bios.date: 11/16/2011 dmi.bios.vendor: American Megatrends Inc. dmi.bios.version: 0402 dmi.board.asset.tag: To be filled by O.E.M. dmi.board.name: P8Z68-V PRO GEN3 dmi.board.vendor: ASUSTeK Computer INC. dmi.board.version: Rev 1.xx dmi.chassis.asset.tag: Asset-1234567890 dmi.chassis.type: 3 dmi.chassis.vendor: Chassis Manufacture dmi.chassis.version: Chassis Version dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr0402:bd11/16/2011:svnSystemmanufacturer:pnSystemProductName:pvrSystemVersion:rvnASUSTeKComputerINC.:rnP8Z68-VPROGEN3:rvrRev1.xx:cvnChassisManufacture:ct3:cvrChassisVersion: dmi.product.name: System Product Name dmi.product.version: System Version dmi.sys.vendor: System manufacturer version.compiz: compiz 1:0.9.9~daily13.03.29-0ubuntu1 version.ia32-libs: ia32-libs N/A version.libdrm2: libdrm2 2.4.43-0ubuntu1 version.libgl1-mesa-dri: libgl1-mesa-dri 9.0.3-0ubuntu1 version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A version.libgl1-mesa-glx: libgl1-mesa-glx 9.0.3-0ubuntu1 version.xserver-xorg-core: xserver-xorg-core 2:1.13.3-0ubuntu4 version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.7.3-0ubuntu2b2 version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.1.0-0ubuntu2 version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.21.5-0ubuntu1 version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.7-0ubuntu1 xserver.bootTime: Sat Apr 6 08:21:40 2013 xserver.configfile: default xserver.devices: input Power Button KEYBOARD, id 6 input Power Button KEYBOARD, id 7 input Logitech Unifying Device. Wireless PID:101b MOUSE, id 8 input Logitech Unifying Device. Wireless PID:2008 KEYBOARD, id 9 input Eee PC WMI hotkeys KEYBOARD, id 10 xserver.errors: xserver.logfile: /var/log/Xorg.0.log xserver.version: 2:1.13.3-0ubuntu4 xserver.video_driver: radeon ** Changed in: xorg-server (Ubuntu) Importance: Undecided => High ** Changed in: xorg-server (Ubuntu) Status: Confirmed => Incomplete -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xorg-server in Ubuntu. https://bugs.launchpad.net/bugs/1165306 Title: Xorg crashed with SIGABRT in __libc_start_main() To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/1165306/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp