Application: kwin (4.4.2 (KDE 4.4.2))
KDE Platform Version: 4.4.2 (KDE 4.4.2)
Qt Version: 4.6.2
Operating System: Linux 2.6.32-24-generic x86_64
Distribution: Ubuntu 10.04.1 LTS

-- Information about the crash:
I had just logged in and was starting a couple of applications (Dolphin, Thunderbird), and KWin suddenly crashed for no reason. I may have switched desktops too rapidly or something.

 -- Backtrace:
Application: KWin (kwin), signal: Segmentation fault
[KCrash Handler]
#5  QRect::isEmpty (this=0x7fffc21d6ea0, r=..., t=QRegion::Rectangle) at ../../include/QtCore/../../src/corelib/tools/qrect.h:235
#6  QRegion (this=0x7fffc21d6ea0, r=..., t=QRegion::Rectangle) at painting/qregion.cpp:3844
#7  0x00007fa927e4e8fa in QRegion::operator+= (this=0x222e470, r=...) at painting/qregion.cpp:4098
#8  0x00007fa92ba2ad8d in KWin::Workspace::addRepaint (this=0x222dfb0, r=...) at ../../kwin/composite.cpp:344
#9  0x00007fa91c68c7be in KWin::BoxSwitchEffect::windowDamaged (this=0x23237f0, w=0x2423f90, damage=<value optimized out>) at ../../../kwin/effects/boxswitch/boxswitch.cpp:308
#10 0x00007fa92ba4a19a in KWin::EffectsHandlerImpl::windowDamaged (this=<value optimized out>, w=0x2423f90, r=...) at ../../kwin/effects.cpp:293
#11 0x00007fa92ba2b07e in KWin::Toplevel::addDamageFull (this=0x2767b00) at ../../kwin/composite.cpp:846
#12 0x00007fa92ba2b0c6 in KWin::Toplevel::discardWindowPixmap (this=0x7fffc21d6ea0) at ../../kwin/composite.cpp:724
#13 0x00007fa92b9be98b in KWin::Client::map (this=0x2767b00) at ../../kwin/client.cpp:1170
#14 0x00007fa92b9c2312 in KWin::Client::internalKeep (this=0x2767b00) at ../../kwin/client.cpp:1152
#15 0x00007fa92b9fe38f in KWin::Client::manage (this=0x2767b00, w=<value optimized out>, isMapped=<value optimized out>) at ../../kwin/manage.cpp:132
#16 0x00007fa92b9b3d22 in KWin::Workspace::createClient (this=0x222dfb0, w=54525999, is_mapped=false) at ../../kwin/workspace.cpp:547
#17 0x00007fa92b9f29d1 in KWin::Workspace::workspaceEvent (this=0x222dfb0, e=0x7fffc21d7b40) at ../../kwin/events.cpp:378
#18 0x00007fa92b9cff58 in KWin::Application::x11EventFilter (this=0x7fffc21d7f30, e=0x7fffc21d7b40) at ../../kwin/main.cpp:361
#19 0x00007fa927d21641 in qt_x11EventFilter (ev=0x7fffc21d7b40) at kernel/qapplication_x11.cpp:399
#20 0x00007fa927d30191 in QApplication::x11ProcessEvent (this=<value optimized out>, event=0x7fffc21d7b40) at kernel/qapplication_x11.cpp:3231
#21 0x00007fa927d5c882 in x11EventSourceDispatch (s=0x2117b90, callback=<value optimized out>, user_data=<value optimized out>) at kernel/qguieventdispatcher_glib.cpp:146
#22 0x00007fa921cf48c2 in g_main_context_dispatch () from /lib/libglib-2.0.so.0
#23 0x00007fa921cf8748 in ?? () from /lib/libglib-2.0.so.0
#24 0x00007fa921cf88fc in g_main_context_iteration () from /lib/libglib-2.0.so.0
#25 0x00007fa927589513 in QEventDispatcherGlib::processEvents (this=0x20fa5b0, flags=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:412
#26 0x00007fa927d5c46e in QGuiEventDispatcherGlib::processEvents (this=0x7fffc21d6ea0, flags=<value optimized out>) at kernel/qguieventdispatcher_glib.cpp:204
#27 0x00007fa92755e992 in QEventLoop::processEvents (this=<value optimized out>, flags=) at kernel/qeventloop.cpp:149
#28 0x00007fa92755ed6c in QEventLoop::exec (this=0x7fffc21d7e70, flags=) at kernel/qeventloop.cpp:201
#29 0x00007fa927562aab in QCoreApplication::exec () at kernel/qcoreapplication.cpp:981
#30 0x00007fa92b9d17be in kdemain (argc=<value optimized out>, argv=<value optimized out>) at ../../kwin/main.cpp:526
#31 0x00007fa92b61dc4d in __libc_start_main (main=<value optimized out>, argc=<value optimized out>, ubp_av=<value optimized out>, init=<value optimized out>, fini=<value optimized out>, 
    rtld_fini=<value optimized out>, stack_end=0x7fffc21d8438) at libc-start.c:226
#32 0x00000000004006b9 in _start ()

Reported using DrKonqi