Application: kwin (4.11.2)
KDE Platform Version: 4.11.2
Qt Version: 4.8.4
Operating System: Linux 3.8.0-31-generic i686
Distribution: Ubuntu 13.04

-- Information about the crash:
- What I was doing when the application crashed:
Changed active Effects and clicked the Apply button.

- Custom settings of the application:
I hope the list of active effect is appended automatically.

The crash can be reproduced sometimes.

-- Backtrace:
Application: KWin (kwin), signal: Segmentation fault
Using host libthread_db library "/lib/i386-linux-gnu/libthread_db.so.1".
[Current thread is 1 (Thread 0xaf304a40 (LWP 8487))]

Thread 3 (Thread 0xa9a81b40 (LWP 8493)):
#0  0xb76e8182 in _dl_sysinfo_int80 () from /lib/ld-linux.so.2
#1  0xb4a8d84b in pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/i386/i686/../i486/pthread_cond_wait.S:187
#2  0xb745ed7c in __pthread_cond_wait (cond=0xb6f83670, mutex=0xb6f83658) at forward.c:149
#3  0xb6e710ad in ?? () from /usr/lib/i386-linux-gnu/libQtScript.so.4
#4  0xb6e710df in ?? () from /usr/lib/i386-linux-gnu/libQtScript.so.4
#5  0xb4a89d78 in start_thread (arg=0xa9a81b40) at pthread_create.c:311
#6  0xb74513de in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:131

Thread 2 (Thread 0xacba4b40 (LWP 8886)):
#0  0xb76e8182 in _dl_sysinfo_int80 () from /lib/ld-linux.so.2
#1  0xb4a8dc33 in pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/i386/i686/../i486/pthread_cond_timedwait.S:250
#2  0xb745edd4 in __pthread_cond_timedwait (cond=0x9b42090, mutex=0x9b42078, abstime=0xacba4228) at forward.c:162
#3  0xb5cb406d in wait (time=30000, this=0x9b42078) at thread/qwaitcondition_unix.cpp:84
#4  QWaitCondition::wait (this=0x9b42048, mutex=0x9b42044, time=30000) at thread/qwaitcondition_unix.cpp:158
#5  0xb5ca660c in QThreadPoolThread::run (this=0x9baf1d0) at concurrent/qthreadpool.cpp:141
#6  0xb5cb3b18 in QThreadPrivate::start (arg=0x9baf1d0) at thread/qthread_unix.cpp:338
#7  0xb4a89d78 in start_thread (arg=0xacba4b40) at pthread_create.c:311
#8  0xb74513de in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:131

Thread 1 (Thread 0xaf304a40 (LWP 8487)):
[KCrash Handler]
#7  deref (this=0xfffffff9) at ../../include/QtCore/../../src/corelib/arch/qatomic_i386.h:132
#8  QString::operator= (this=0x9deceec, other=...) at tools/qstring.cpp:1411
#9  0xb5db6f2b in QLibraryPrivate::resolve_sys (this=0x9deceec, symbol=0xb7357c7e "create_factory") at plugin/qlibrary_unix.cpp:313
#10 0xb5db0039 in QLibraryPrivate::resolve (this=0x9decec8, symbol=0xb7357c7e "create_factory") at plugin/qlibrary.cpp:457
#11 0xb5db1f9d in QLibrary::resolve (this=0x9decec8, this@entry=0x9b62720, symbol=symbol@entry=0xb7357c7e "create_factory") at plugin/qlibrary.cpp:1144
#12 0xb61b6113 in KLibrary::resolveFunction (this=0x9b62720, symname=0xb7357c7e "create_factory") at ../../kdecore/util/klibrary.cpp:183
#13 0xb73502db in KDecorationPlugins::loadPlugin(QString) () from /usr/lib/libkdecorations.so.4abi1
#14 0xb7350866 in KDecorationPlugins::reset(unsigned long) () from /usr/lib/libkdecorations.so.4abi1
#15 0xb757e52f in ?? () from /usr/lib/kde4/libkdeinit/libkdeinit4_kwin.so
#16 0xb5ddcb56 in QMetaObject::activate (sender=sender@entry=0x9b40ccc, m=m@entry=0xb5f314b8 <QTimer::staticMetaObject>, local_signal_index=local_signal_index@entry=0, argv=argv@entry=0x0) at kernel/qobject.cpp:3539
#17 0xb5e2fee5 in QTimer::timeout (this=this@entry=0x9b40ccc) at .moc/release-shared/moc_qtimer.cpp:148
#18 0xb5de6126 in QTimer::timerEvent (this=0x9b40ccc, e=0xbf9678f0) at kernel/qtimer.cpp:280
#19 0xb5de22d4 in QObject::event (this=0x9b40ccc, e=0xbf9678f0) at kernel/qobject.cpp:1156
#20 0xb52b4c7c in QApplicationPrivate::notify_helper (this=0x9a297f0, receiver=0x9b40ccc, e=0xbf9678f0) at kernel/qapplication.cpp:4567
#21 0xb52b7b94 in QApplication::notify (this=0xbf9678f0, receiver=0x9b40ccc, e=0xbf9678f0) at kernel/qapplication.cpp:3949
#22 0xb6aabec1 in KApplication::notify (this=0xbf967cb8, receiver=0x9b40ccc, event=0xbf9678f0) at ../../kdeui/kernel/kapplication.cpp:311
#23 0xb75a670f in ?? () from /usr/lib/kde4/libkdeinit/libkdeinit4_kwin.so
#24 0xb5dc690e in QCoreApplication::notifyInternal (this=0xbf967cb8, receiver=0x9b40ccc, event=event@entry=0xbf9678f0) at kernel/qcoreapplication.cpp:946
#25 0xb5dfb8c0 in sendEvent (event=0xbf9678f0, receiver=<optimized out>) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:231
#26 QTimerInfoList::activateTimers (this=0x9a2a1b4) at kernel/qeventdispatcher_unix.cpp:622
#27 0xb5dfb945 in QEventDispatcherUNIX::activateTimers (this=0x9a2a1b4, this@entry=0x9a28820) at kernel/qeventdispatcher_unix.cpp:879
#28 0xb5dfbab8 in QEventDispatcherUNIX::processEvents (this=this@entry=0x9a28820, flags=...) at kernel/qeventdispatcher_unix.cpp:941
#29 0xb536c5a3 in QEventDispatcherX11::processEvents (this=0x9a28820, flags=...) at kernel/qeventdispatcher_x11.cpp:152
#30 0xb5dc53ec in QEventLoop::processEvents (this=this@entry=0xbf967b38, flags=...) at kernel/qeventloop.cpp:149
#31 0xb5dc56e1 in QEventLoop::exec (this=this@entry=0xbf967b38, flags=...) at kernel/qeventloop.cpp:204
#32 0xb5dcb3fa in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1218
#33 0xb52b2fc4 in QApplication::exec () at kernel/qapplication.cpp:3828
#34 0xb75a5fa5 in kdemain () from /usr/lib/kde4/libkdeinit/libkdeinit4_kwin.so
#35 0x0804855b in ?? ()
#36 0xb7379935 in __libc_start_main (main=0x8048540, argc=1, ubp_av=0xbf967da4, init=0x8048670 <__libc_csu_init>, fini=0x80486e0 <__libc_csu_fini>, rtld_fini=0xb76f6600 <_dl_fini>, stack_end=0xbf967d9c) at libc-start.c:260
#37 0x08048581 in _start ()

Reported using DrKonqi