Version:            (using KDE 4.0.2)
Installed from:    Debian testing/unstable Packages
OS:                Linux

after several clicks while kwin being unresponsive (clicks had no effect on any application) kwin crashed:

(no debugging symbols found)
Using host libthread_db library "/lib/i686/cmov/libthread_db.so.1".
(no debugging symbols found)
(no debugging symbols found)
[Thread debugging using libthread_db enabled]
[New Thread 0xb7f10b20 (LWP 12660)]
[New Thread 0xb68a4b90 (LWP 14021)]
[KCrash handler]
#6  0x41d6fd4a in QMetaObject::activate (sender=) at kernel/qobject.cpp:3152
#7  0x41d0801e in QProcess::stateChanged (this=)
    at .moc/debug-shared/moc_qprocess.cpp:147
#8  0x41d0a325 in QProcessPrivate::_q_processDied (this=)
    at io/qprocess.cpp:676
#9  0x41d3e78a in QProcessPrivate::waitForFinished (this=)
    at io/qprocess_unix.cpp:1160
#10 0x41d09003 in QProcess::waitForFinished (this=) at io/qprocess.cpp:1297
#11 0x41d098c3 in ~QProcess (this=) at io/qprocess.cpp:759
#12 0x41024a63 in ?? () from /usr/lib/libkdeinit4_kwin.so
#13 0x0813b900 in ?? ()
#14 0xa2e3768f in ?? ()
#15 0xbfdb8e88 in ?? ()
#16 0x4e33e501 in XFlush () from /usr/lib/libX11.so.6
#17 0x41049248 in ?? () from /usr/lib/libkdeinit4_kwin.so
#18 0x0816cff8 in ?? ()
#19 0xa2e3768f in ?? ()
#20 0xbfdb8e98 in ?? ()
#21 0x42339ca0 in ?? () from /usr/lib/libkdeui.so.5
#22 0xbfdb93c0 in ?? ()
#23 0x0811bb40 in ?? ()
#24 0xbfdb8f68 in ?? ()
#25 0x422ef9e3 in NETRootInfo::event (this=<value optimized out>, 
    event=<value optimized out>, properties=<value optimized out>, 
    properties_size=<value optimized out>)
    at /tmp/buildd/kde4libs-4.0.2/kdeui/windowmanagement/netwm.cpp:1949
Backtrace stopped: frame did not save the PC
#0  0xffffe410 in __kernel_vsyscall ()