Application that crashed: kwin
Version of the application: 4.2.95 (KDE 4.2.95 (KDE 4.3 RC1)) "release 139"
KDE Version: 4.2.95 (KDE 4.2.95 (KDE 4.3 RC1)) "release 139"
Qt Version: 4.5.2
Operating System: Linux 2.6.27.23-0.1-pae i686
Distribution: "openSUSE 11.1 (i586)"

What I was doing when the application crashed:
i switch the windows with alt+tab

 -- Backtrace:
Application: KWin (kwin), signal: Segmentation fault
[KCrash Handler]
#6  0xb2dbeb5f in KWin::CoverSwitchEffect::calculateItemSizes (this=0x8227d90) at /usr/src/debug/kdebase-workspace-4.2.95/kwin/effects/coverswitch/coverswitch.cpp:1052
#7  0xb2dbff28 in KWin::CoverSwitchEffect::prePaintScreen (this=0x8227d90, data=@0xbfff8c14, time=84) at /usr/src/debug/kdebase-workspace-4.2.95/kwin/effects/coverswitch/coverswitch.cpp:110
#8  0xb808744d in KWin::EffectsHandlerImpl::prePaintScreen (this=0x81969b8, data=@0xbfff8c14, time=84) at /usr/src/debug/kdebase-workspace-4.2.95/kwin/effects.cpp:112
#9  0xb2d8f1ca in KWin::LoginEffect::prePaintScreen (this=0x81ec8f8, data=@0xbfff8c14, time=84) at /usr/src/debug/kdebase-workspace-4.2.95/kwin/effects/login/login.cpp:52
#10 0xb808744d in KWin::EffectsHandlerImpl::prePaintScreen (this=0x81969b8, data=@0xbfff8c14, time=84) at /usr/src/debug/kdebase-workspace-4.2.95/kwin/effects.cpp:112
#11 0xb2de5bb9 in KWin::TrackMouseEffect::prePaintScreen (this=0x81e46d0, data=@0xbfff8c14, time=84) at /usr/src/debug/kdebase-workspace-4.2.95/kwin/effects/trackmouse/trackmouse.cpp:66
#12 0xb808744d in KWin::EffectsHandlerImpl::prePaintScreen (this=0x81969b8, data=@0xbfff8c14, time=84) at /usr/src/debug/kdebase-workspace-4.2.95/kwin/effects.cpp:112
#13 0xb2db9b80 in KWin::ZoomEffect::prePaintScreen (this=0x8236800, data=@0xbfff8c14, time=84) at /usr/src/debug/kdebase-workspace-4.2.95/kwin/effects/zoom/zoom.cpp:59
#14 0xb808744d in KWin::EffectsHandlerImpl::prePaintScreen (this=0x81969b8, data=@0xbfff8c14, time=84) at /usr/src/debug/kdebase-workspace-4.2.95/kwin/effects.cpp:112
#15 0xb8070ec9 in KWin::Scene::paintScreen (this=0x81974c0, mask=0xbfff8ca4, region=0xbfff8d64) at /usr/src/debug/kdebase-workspace-4.2.95/kwin/scene.cpp:113
#16 0xb808091a in KWin::SceneOpenGL::paint (this=0x81974c0, damage={d = 0xbfff8d64, static shared_empty = {ref = {_q_value = 9575}, rgn = 0x0, xrectangles = 0x0, qt_rgn = 0x0}}, toplevels=
        {{p = {static shared_null = {ref = {_q_value = 15988}, alloc = 0, begin = 0, end = 0, sharable = 1, array = {0x0}}, d = 0xbfff8d60}, d = 0xbfff8d60}})
    at /usr/src/debug/kdebase-workspace-4.2.95/kwin/scene_opengl.cpp:746
#17 0xb806bf66 in KWin::Workspace::performCompositing (this=0x817e378) at /usr/src/debug/kdebase-workspace-4.2.95/kwin/composite.cpp:418
#18 0xb7ffccbd in KWin::Workspace::qt_metacall (this=0x817e378, _c=QMetaObject::InvokeMetaMethod, _id=149, _a=0xbfff8e38) at /usr/src/debug/kdebase-workspace-4.2.95/build/kwin/workspace.moc:473
#19 0xb6be6788 in QMetaObject::activate (sender=0x817e5dc, from_signal_index=4, to_signal_index=4, argv=0x0) at kernel/qobject.cpp:3113
#20 0xb6be7412 in QMetaObject::activate (sender=0x817e5dc, m=0xb6cc8904, local_signal_index=0, argv=0x0) at kernel/qobject.cpp:3187
#21 0xb6c22fe7 in QTimer::timeout (this=0x817e5dc) at .moc/release-shared/moc_qtimer.cpp:128
#22 0xb6becc0e in QTimer::timerEvent (this=0x817e5dc, e=0xbfff9300) at kernel/qtimer.cpp:261
#23 0xb6be172f in QObject::event (this=0x817e5dc, e=0xbfff9300) at kernel/qobject.cpp:1075
#24 0xb6e5c7fc in QApplicationPrivate::notify_helper (this=0x8065d58, receiver=0x817e5dc, e=0xbfff9300) at kernel/qapplication.cpp:4056
#25 0xb6e64aee in QApplication::notify (this=0xbfff9604, receiver=0x817e5dc, e=0xbfff9300) at kernel/qapplication.cpp:3603
#26 0xb7b7110d in KApplication::notify (this=0xbfff9604, receiver=0x817e5dc, event=0xbfff9300) at /usr/src/debug/kdelibs-4.2.95/kdeui/kernel/kapplication.cpp:302
#27 0xb801449d in KWin::Application::notify (this=0xbfff9604, o=0x817e5dc, e=0xbfff9300) at /usr/src/debug/kdebase-workspace-4.2.95/kwin/main.cpp:371
#28 0xb6bd116b in QCoreApplication::notifyInternal (this=0xbfff9604, receiver=0x817e5dc, event=0xbfff9300) at kernel/qcoreapplication.cpp:610
#29 0xb6c005f6 in QTimerInfoList::activateTimers (this=0x8068d24) at kernel/qcoreapplication.h:213
#30 0xb6bfc980 in timerSourceDispatch (source=0x8068cf0) at kernel/qeventdispatcher_glib.cpp:165
#31 0xb4ea89c8 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#32 0xb4eac083 in ?? () from /usr/lib/libglib-2.0.so.0
#33 0xb4eac241 in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#34 0xb6bfc8d8 in QEventDispatcherGlib::processEvents (this=0x8065d38, flags={i = -1073769304}) at kernel/qeventdispatcher_glib.cpp:327
#35 0xb6efccc5 in QGuiEventDispatcherGlib::processEvents (this=0x8065d38, flags={i = -1073769256}) at kernel/qguieventdispatcher_glib.cpp:202
#36 0xb6bcf78a in QEventLoop::processEvents (this=0xbfff9550, flags={i = -1073769192}) at kernel/qeventloop.cpp:149
#37 0xb6bcfbd2 in QEventLoop::exec (this=0xbfff9550, flags={i = -1073769128}) at kernel/qeventloop.cpp:201
#38 0xb6bd2079 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:888
#39 0xb6e5c677 in QApplication::exec () at kernel/qapplication.cpp:3525
#40 0xb8016d63 in kdemain (argc=3, argv=0xbfff97e4) at /usr/src/debug/kdebase-workspace-4.2.95/kwin/main.cpp:527
#41 0x080487c2 in main (argc=136010928, argv=0xfffffde9) at /usr/src/debug/kdebase-workspace-4.2.95/build/kwin/kwin_dummy.cpp:3

Reported using DrKonqi