Application that crashed: kwin
Version of the application: 4.2.90 (KDE 4.2.90 (KDE 4.3 Beta2))
KDE Version: 4.2.90 (KDE 4.2.90 (KDE 4.3 Beta2))
Qt Version: 4.5.1
Operating System: Linux 2.6.30-8-generic i686
Distribution: Ubuntu karmic (development branch)

 -- Backtrace:
Application: KWin (kwin), signal: Segmentation fault
[KCrash Handler]
#6  0x05c6e5ae in KWin::BoxSwitchEffect::calculateItemSizes (this=0x9865b98) at ../../../kwin/effects/boxswitch/boxswitch.cpp:650
#7  0x05c6eeef in KWin::BoxSwitchEffect::tabBoxUpdated (this=0x9865b98) at ../../../kwin/effects/boxswitch/boxswitch.cpp:428
#8  0x00da18d3 in KWin::EffectsHandlerImpl::tabBoxUpdated (this=0x9810140) at ../../kwin/effects.cpp:303
#9  0x00d31554 in KWin::TabBox::setCurrentClient (this=0x9904708, newClient=0x9af1900) at ../../kwin/tabbox.cpp:498
#10 0x00d31687 in KWin::TabBox::nextPrev (this=0x9904708, next=true) at ../../kwin/tabbox.cpp:417
#11 0x00d136e5 in KWin::Workspace::removeClient (this=0x981cae0, c=0x9814cf0) at ../../kwin/workspace.cpp:627
#12 0x00d20a52 in KWin::Client::releaseWindow (this=0x9814cf0, on_shutdown=false) at ../../kwin/client.cpp:235
#13 0x00d41dad in KWin::Client::unmapNotifyEvent (this=0x9814cf0, e=0xbffedf1c) at ../../kwin/events.cpp:796
#14 0x00d43524 in KWin::Client::windowEvent (this=0x9814cf0, e=0xbffedf1c) at ../../kwin/events.cpp:642
#15 0x00d43ce4 in KWin::Workspace::workspaceEvent (this=0x981cae0, e=0xbffedf1c) at ../../kwin/events.cpp:305
#16 0x00d2af72 in KWin::Application::x11EventFilter (this=0xbffee2c8, e=0xbffedf1c) at ../../kwin/main.cpp:361
#17 0x013ae670 in qt_x11EventFilter (ev=0xbffedf1c) at kernel/qapplication_x11.cpp:375
#18 0x013bfde0 in QApplication::x11ProcessEvent (this=0xbffee2c8, event=0xbffedf1c) at kernel/qapplication_x11.cpp:3287
#19 0x013ee292 in x11EventSourceDispatch (s=0x973be00, callback=0, user_data=0x0) at kernel/qguieventdispatcher_glib.cpp:146
#20 0x027e5ad8 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#21 0x027e9070 in ?? () from /usr/lib/libglib-2.0.so.0
#22 0x027e91a3 in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#23 0x06131f9c in QEventDispatcherGlib::processEvents (this=0x9738b38, flags={i = 36}) at kernel/qeventdispatcher_glib.cpp:324
#24 0x013ed975 in QGuiEventDispatcherGlib::processEvents (this=0x9738b38, flags={i = 36}) at kernel/qguieventdispatcher_glib.cpp:202
#25 0x061050a9 in QEventLoop::processEvents (this=0xbffee214, flags=) at kernel/qeventloop.cpp:149
#26 0x061054f2 in QEventLoop::exec (this=0xbffee214, flags={i = 0}) at kernel/qeventloop.cpp:200
#27 0x0610787f in QCoreApplication::exec () at kernel/qcoreapplication.cpp:888
#28 0x0134ba97 in QApplication::exec () at kernel/qapplication.cpp:3526
#29 0x00d2da08 in kdemain (argc=3, argv=0xbffee4a4) at ../../kwin/main.cpp:525
#30 0x080485bb in main (argc=3, argv=0xbffee4a4) at kwin_dummy.cpp:3

Reported using DrKonqi