Firefox crash brings X Server down

I have reported this problem before.

Environment:
Nvidia Driver 185.18.36
Firefox 3.5.8
kernel: 2.6.31-20-generic
ii xserver-xorg 1:7.4+3ubuntu10 the X.Org X server
ii xserver-xorg-core 2:1.6.4-2ubuntu4.2 Xorg X server - core server
architecture i386
Release: 9.10 Karmic Koala
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https://answers.launchpad.net/ubuntu/+question/93420

I thought it was caused by the pages with heavy ADF. But it is not in fact. Yesterday I encountered another Firefox crash when using Echofon add-on to tweet. It brought down the X Server 1s after Firefox crashed.

I have attached the full Error log for your analysis.

=================================================================================================
Could not locate Tomboy on D-Bus. Perhaps it's not running?
Firefox.PlacesItemSource "Firefox Places" encountered an error in UpdateItems: System.NullReferenceException: Object reference not set to an instance of an object
  at Mono.Data.SqliteClient.SqliteDataReader.GetString (Int32 i) [0x00000]
  at Firefox.PlacesItemSource+<LoadPlaceItems>c__Iterator3.MoveNext () [0x00000]
  at System.Collections.Generic.List`1[Firefox.PlaceItem].AddEnumerable (IEnumerable`1 enumerable) [0x00000]
  at System.Collections.Generic.List`1[Firefox.PlaceItem]..ctor (IEnumerable`1 collection) [0x00000]
  at System.Linq.Enumerable.ToArray[PlaceItem] (IEnumerable`1 source) [0x00000]
  at Firefox.PlacesItemSource.UpdateItems () [0x00000]
  at Do.Universe.Safe.SafeItemSource.UpdateItems () [0x00000] .
Could not locate Tomboy on D-Bus. Perhaps it's not running?
Firefox.PlacesItemSource "Firefox Places" encountered an error in UpdateItems: System.NullReferenceException: Object reference not set to an instance of an object
  at Mono.Data.SqliteClient.SqliteDataReader.GetString (Int32 i) [0x00000]
  at Firefox.PlacesItemSource+<LoadPlaceItems>c__Iterator3.MoveNext () [0x00000]
  at System.Collections.Generic.List`1[Firefox.PlaceItem].AddEnumerable (IEnumerable`1 enumerable) [0x00000]
  at System.Collections.Generic.List`1[Firefox.PlaceItem]..ctor (IEnumerable`1 collection) [0x00000]
  at System.Linq.Enumerable.ToArray[PlaceItem] (IEnumerable`1 source) [0x00000]
  at Firefox.PlacesItemSource.UpdateItems () [0x00000]
  at Do.Universe.Safe.SafeItemSource.UpdateItems () [0x00000] .
gnome-power-manager: Fatal IO error 11 (Resource temporarily unavailable) on X server :0.0.
Conky: X Error: Display 9510788

gnome-session: Fatal IO error 11 (Resource temporarily unavailable) on X server :0.0.
XIO: fatal IO error 104 (Connection reset by peer) on X server ":0.0"

      after 36105 requests (36104 known processed) with 0 events remaining.

gnome-panel: Fatal IO error 11 (Resource temporarily unavailable) on X server :0.0.
gnome-screensaver: Fatal IO error 11 (Resource temporarily unavailable) on X server :0.0.
gdu-notification-daemon: Fatal IO error 11 (Resource temporarily unavailable) on X server :0.0.
gnome-settings-daemon: Fatal IO error 11 (Resource temporarily unavailable) on X server :0.0.
XIO: fatal IO error 104 (Connection reset by peer) on X server ":0.0"

      after 1156198 requests (1156196 known processed) with 1 events remaining.

polkit-gnome-authentication-agent-1: Fatal IO error 11 (Resource temporarily unavailable) on X server :0.0.
nautilus: Fatal IO error 11 (Resource temporarily unavailable) on X server :0.0.
gtk-window-decorator: Fatal IO error 11 (Resource temporarily unavailable) on X server :0.0.

** (tsclient:30820): WARNING **:
XIO: fatal IO error 104 (Connection reset by peer) on X server ":0.0"

      after 514222 requests (514220 known processed) with 0 events remaining.

The Errors are exactly the same as what was mentioned in the question: