Please look for the original launchpad report(and complete stacktrace) at:

https://bugs.launchpad.net/ubuntu/+source/qtcreator/+bug/982996

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I am on Ubuntu12.04 64bit updated to 16.4.2012.

I was going trough menu-> Extras -> Configuration. One of the sidebar categories in there caused the crash.

ProblemType: Crash
DistroRelease: Ubuntu 12.04
Package: qtcreator 2.4.1-0ubuntu2
ProcVersionSignature: Ubuntu 3.2.0-23.36-generic 3.2.14
Uname: Linux 3.2.0-23-generic x86_64
ApportVersion: 2.0.1-0ubuntu3
Architecture: amd64
Date: Mon Apr 16 13:22:32 2012
ExecutablePath: /usr/bin/qtcreator
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Beta amd64+mac (20120328)
ProcCmdline: qtcreator
ProcEnviron:
PATH=(custom, no username)
LANG=de_DE.UTF-8
SHELL=/bin/bash
Signal: 11
SourcePackage: qtcreator
StacktraceTop:
QDeclarativeItem::~QDeclarativeItem() () from /usr/lib/x86_64-linux-gnu/libQtDeclarative.so.4
?? () from /usr/lib/x86_64-linux-gnu/libQtDeclarative.so.4
QObject::event(QEvent*) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
QApplication::notify(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
Title: qtcreator crashed with SIGSEGV in QDeclarativeItem::~QDeclarativeItem()
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dialout dip lpadmin plugdev sambashare sudo
XsessionErrors: (compiz:3252): GConf-CRITICAL **: gconf_client_add_dir: assertion `gconf_valid_key (dirname, NULL)' failed