This seems to have happened during boot after and upgrade to Quantal.
From dmesg:
[ 265.064022] gsettings-data-[3433] trap int3 ip:7f5077f46fcf sp:7fff3f9b1440 error:0
[ 296.370802] gsettings-data-[3445] trap int3 ip:7fbfdd63cfcf sp:7fff94c810b0 error:0
[ 325.684418] gsettings-data-[3755] trap int3 ip:7f40b6559fcf sp:7fffcf35de00 error:0
[ 326.194013] gsettings-data-[3768] trap int3 ip:7f267b69cfcf sp:7fff2ec514c0 error:0
ProblemType: Crash
DistroRelease: Ubuntu 12.10
Package: gconf2 3.2.5-0ubuntu2
ProcVersionSignature: Ubuntu 3.5.0-13.14-generic 3.5.3
Uname: Linux 3.5.0-13-generic x86_64
ApportVersion: 2.5.1-0ubuntu3
Architecture: amd64
CheckboxSubmission: fee5e196cb921cbd36888f428b38b488
CheckboxSystem: 2a6f54df59af338184485e85cbcf0d32
Date: Thu Aug 30 06:46:29 2012
ExecutablePath: /usr/bin/gsettings-data-convert
ProcCmdline: gsettings-data-convert --file=/usr/lib/compiz/migration/compiz-profile-active-unity.convert
ProcEnviron:
PATH=(custom, no user)
LANG=en_US.UTF-8
SHELL=/bin/zsh
Signal: 5
SourcePackage: gconf
StacktraceTop:
g_settings_schema_get_value (schema=schema@entry=0xd30d80, key=key@entry=0xd45be0 "force-message-limit") at /build/buildd/glib2.0-2.33.10/./gio/gsettingsschema.c:640
g_settings_schema_key_init (key=key@entry=0x7fff3f9b1680, schema=0xd30d80, name=name@entry=0xd45be0 "force-message-limit") at /build/buildd/glib2.0-2.33.10/./gio/gsettingsschema.c:751
g_settings_set_value (settings=settings@entry=0xcfe770, key=key@entry=0xd45be0 "force-message-limit", value=0x7f5070016190) at /build/buildd/glib2.0-2.33.10/./gio/gsettings.c:1350
g_settings_set (settings=0xcfe770, key=0xd45be0 "force-message-limit", format=<optimized out>) at /build/buildd/glib2.0-2.33.10/./gio/gsettings.c:1449
?? ()
Title: gsettings-data-convert crashed with signal 5 in g_settings_schema_get_value()
UpgradeStatus: Upgraded to quantal on 2012-08-29 (1 days ago)
UserGroups: adm admin audio cdrom dialout dip family floppy fuse libvirtd lpadmin plugdev pulse pulse-access sambashare sbuild scanner video
Thank you for taking the time to report this crash and helping to make this software better. This particular crash has already been reported and is a duplicate of bug #945144, so is being marked as such. Please look at the other bug report to see if there is any missing information that you can provide, or to see if there is a workaround for the bug. Additionally, any further discussion regarding the bug should occur in the other report. Please continue to report any other bugs you may find.