Sometimes tab composition is lost between sessions

normally Firefox keeps all tabs URLs and/or windows stored between sessions, so next time I launch it, it runs all of them again. For that reason I have configuration parameter "when firefox starts:" set to "Show my windows and tabs from last time" in options panel. But sometimes (and this time again) it acts as if no tabs were stored. It launches with single tab open, with startup page with URL (this time) http://start.ubuntu.com/12.04/Google/?sourceid=hp

this loss of state is EXTREMELY painful - it is not even predictable and rare, yet if you work with several tens of tabs open (50-70), the unexplainable loss of state makes it very pain. It is like I can not rely on state save for 100% and always should do manual record of every single tab URLs and windows before I close browser.

I find it extremely poor implementation that there is no error message about browser not able read state saved or whether state save had happened before browser quit at all or what else happened - merely no error message.

Also, I have seen this problem few times already (maybe 4 or 5 times), on stock Ubuntu 12.xx and now on Xubuntu too, so this is cross-distribution problem.

The other part of problem is that I can't find instructions how to get state of browser to find why this particular time "tab restore" failed and instead I see stupid about:startpage.

I had suspicion in past cases it was because apt subsystem update of packages related to firefox parts. This time I see that between previous launch of browser there was only one apt/dpkg update, then browser had been shutdown properly. this is snippet from /var/log/apt/history.log

Start-Date: 2012-05-19 01:38:03
Commandline: aptdaemon role='role-commit-packages' sender=':1.55'
Upgrade: icedtea-6-jre-cacao:i386 (6b24-1.11.1-4ubuntu2, 6b24-1.11.1-4ubuntu3), openjdk-6-jre-headless:i386 (6b24-1.11.1-4ubuntu2, 6b24-1.11.1-4ubuntu3), openjdk-6-jre:i386 (6b24-1.11.1-4ubuntu2, 6b24-1.11.1-4ubuntu3), icedtea-6-jre-jamvm:i386 (6b24-1.11.1-4ubuntu2, 6b24-1.11.1-4ubuntu3), openjdk-6-jre-lib:i386 (6b24-1.11.1-4ubuntu2, 6b24-1.11.1-4ubuntu3)
End-Date: 2012-05-19 01:38:21

Also I had installed Firefox sync plugin across all desktops/laptops few weeks ago but it presence did not help either - it did not restore anything. Zero.

I don't know how to explain other way how annoying and disturbing it is. I don't know how to collect info to submit enough now, and next time I will run it, it will restore everything I managed to open last time just Ok. So I can not afford to run it again. And other instructions from https://wiki.ubuntu.com/MozillaTeam/Bugs look not applicable for this case too.

$ lsb_release -rd
Description: Ubuntu 12.04 LTS
Release: 12.04

$ apt-cache policy firefox
firefox:
  Installed: 12.0+build1-0ubuntu0.12.04.1
  Candidate: 12.0+build1-0ubuntu0.12.04.1
  Version table:
 *** 12.0+build1-0ubuntu0.12.04.1 0
        500 http://fi.archive.ubuntu.com/ubuntu/ precise-updates/main i386 Packages
        500 http://security.ubuntu.com/ubuntu/ precise-security/main i386 Packages
        100 /var/lib/dpkg/status
     11.0+build1-0ubuntu4 0
        500 http://fi.archive.ubuntu.com/ubuntu/ precise/main i386 Packages

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: firefox 12.0+build1-0ubuntu0.12.04.1
ProcVersionSignature: Ubuntu 3.2.0-24.37-generic-pae 3.2.14
Uname: Linux 3.2.0-24-generic-pae i686
AddonCompatCheckDisabled: False
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.24.
AplayDevices:
 **** List of PLAYBACK Hardware Devices ****
 card 0: Intel [HDA Intel], device 0: CONEXANT Analog [CONEXANT Analog]
   Subdevices: 1/1
   Subdevice #0: subdevice #0
ApportVersion: 2.0.1-0ubuntu7
Architecture: i386
ArecordDevices:
 **** List of CAPTURE Hardware Devices ****
 card 0: Intel [HDA Intel], device 0: CONEXANT Analog [CONEXANT Analog]
   Subdevices: 1/1
   Subdevice #0: subdevice #0
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: silpol 1717 F.... xfce4-volumed
                      silpol 1741 F.... pulseaudio
 /dev/snd/controlC29: silpol 1717 F.... xfce4-volumed
BuildID: 20120423122624
Card0.Amixer.info:
 Card hw:0 'Intel'/'HDA Intel at 0xf0620000 irq 47'
   Mixer name : 'Conexant CX20561 (Hermosa)'
   Components : 'HDA:14f15051,17aa211f,00100000'
   Controls : 20
   Simple ctrls : 12
Card29.Amixer.info:
 Card hw:29 'ThinkPadEC'/'ThinkPad Console Audio Control at EC reg 0x30, fw 6EHT09WW-1.02'
   Mixer name : 'ThinkPad EC 6EHT09WW-1.02'
   Components : ''
   Controls : 1
   Simple ctrls : 1
Card29.Amixer.values:
 Simple mixer control 'Console',0
   Capabilities: pswitch pswitch-joined penum
   Playback channels: Mono
   Mono: Playback [on]
Channel: release
Date: Sat May 19 19:26:44 2012
ForcedLayersAccel: False
IfupdownConfig:
 auto lo
 iface lo inet loopback
IncompatibleExtensions:
 NoScript - ID={73a6fe31-595d-460b-a920-fcc0f8843232}, Version=2.4.1, minVersion=1.9a2, maxVersion=1.9.6, Location=app-profile, Type=extension, Active=Yes
 Magnet Link Shortener - ID=jid0-ckZ2R9z06irIX79o2FXGDgWCiKk@jetpack, Version=1.2.rev183, minVersion=4.0b7, maxVersion=4.0.*, Location=app-profile, Type=extension, Active=Yes
InstallationMedia: Xubuntu 11.10 "Oneiric Ocelot" - Release i386 (20111012)
IpRoute:
 default via 192.168.255.1 dev wlan0 proto static
 169.254.0.0/16 dev wlan0 scope link metric 1000
 192.168.255.0/24 dev wlan0 proto kernel scope link src 192.168.255.7 metric 2
Plugins:
 Shockwave Flash - Lib=libflashplayer.so, Location=/usr/lib/flashplugin-installer
 IcedTea-Web Plugin (using IcedTea-Web 1.2 (1.2-2ubuntu1)) - Lib=IcedTeaPlugin.so, Location=/usr/lib/jvm/java-6-openjdk-i386/jre/lib/i386
 Google Talk Plugin Video Accelerator - Lib=libnpgtpo3dautoplugin.so, Location=/opt/google/talkplugin
 Google Talk Plugin - Lib=libnpgoogletalk.so, Location=/opt/google/talkplugin
 VLC Web Plugin - Lib=libvlcplugin.so, Location=/usr/lib/mozilla/plugins
Profiles: Profile0 (Default) - LastVersion=12.0/20120423122624 (Running)
RunningIncompatibleAddons: True
SourcePackage: firefox
UpgradeStatus: Upgraded to precise on 2012-05-08 (10 days ago)
dmi.bios.date: 10/09/2008
dmi.bios.vendor: LENOVO
dmi.bios.version: 6EET21WW (1.02 )
dmi.board.name: 4057AL1
dmi.board.vendor: LENOVO
dmi.board.version: Not Available
dmi.chassis.asset.tag: L3AAM4C
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Not Available
dmi.modalias: dmi:bvnLENOVO:bvr6EET21WW(1.02):bd10/09/2008:svnLENOVO:pn4057AL1:pvrThinkPadX301:rvnLENOVO:rn4057AL1:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable:
dmi.product.name: 4057AL1
dmi.product.version: ThinkPad X301
dmi.sys.vendor: LENOVO