Application that crashed: plasma-desktop
Version of the application: 0.3
KDE Version: 4.3.4 (KDE 4.3.4)
Qt Version: 4.5.3
Operating System: Linux 2.6.31.9-174.fc12.x86_64 x86_64

What I was doing when the application crashed:
I was fiddling with my widgets, and I decided to see how the system monitor plasmoid looked in the panel, rather than on the desktop - disappointed with the result, I removed the object from the panel, and was instantly greeted by "plasma workspace crashed." 

 -- Backtrace:
Application: Plasma Workspace (plasma-desktop), signal: Segmentation fault
82	T_PSEUDO (SYSCALL_SYMBOL, SYSCALL_NAME, SYSCALL_NARGS)
[Current thread is 1 (Thread 0x7faddee26840 (LWP 1881))]

Thread 2 (Thread 0x7fadc7266710 (LWP 1882)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:162
#1  0x0000003ab145addb in wait (time=18446744073709551615, this=<value optimized out>) at thread/qwaitcondition_unix.cpp:87
#2  QWaitCondition::wait (time=18446744073709551615, this=<value optimized out>) at thread/qwaitcondition_unix.cpp:159
#3  0x0000003ab2881af4 in QHostInfoAgent::run (this=0x120bf70) at kernel/qhostinfo.cpp:260
#4  0x0000003ab1459d25 in QThreadPrivate::start (arg=0x120bf70) at thread/qthread_unix.cpp:188
#5  0x0000003aa6c06a3a in start_thread (arg=<value optimized out>) at pthread_create.c:297
#6  0x0000003aa64ddf3d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#7  0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7faddee26840 (LWP 1881)):
[KCrash Handler]
#5  0x0000003ab3f09de4 in QGraphicsItem::isWidget (this=0x220dc70) at graphicsview/qgraphicsitem.cpp:1146
#6  0x0000003ab3f0c519 in QGraphicsItem::isWindow (this=0x220dc70) at graphicsview/qgraphicsitem.cpp:1159
#7  0x0000003ab3f3fa89 in QGraphicsScene::event (this=0xb7bbb0, event=<value optimized out>) at graphicsview/qgraphicsscene.cpp:3850
#8  0x0000003ab398f65c in QApplicationPrivate::notify_helper (this=0xb88820, receiver=0xb7bbb0, e=0x7fff16fcb440) at kernel/qapplication.cpp:4065
#9  0x0000003ab39968ce in QApplication::notify (this=<value optimized out>, receiver=0xb7bbb0, e=0x7fff16fcb440) at kernel/qapplication.cpp:4030
#10 0x0000003ab4e11a66 in KApplication::notify (this=0xb78510, receiver=0xb7bbb0, event=0x7fff16fcb440) at /usr/src/debug/kdelibs-4.3.4/kdeui/kernel/kapplication.cpp:302
#11 0x0000003ab153ee6c in QCoreApplication::notifyInternal (this=0xb78510, receiver=0xb7bbb0, event=0x7fff16fcb440) at kernel/qcoreapplication.cpp:610
#12 0x0000003ab3f512ae in sendEvent (event=0x7fff16fcb440, receiver=<value optimized out>) at ../../src/corelib/kernel/qcoreapplication.h:213
#13 QGraphicsView::viewportEvent (event=0x7fff16fcb440, receiver=<value optimized out>) at graphicsview/qgraphicsview.cpp:2880
#14 0x0000003ab153e187 in QCoreApplicationPrivate::sendThroughObjectEventFilters (this=<value optimized out>, receiver=0x16ddd70, event=0x7fff16fcb440) at kernel/qcoreapplication.cpp:726
#15 0x0000003ab398f62c in QApplicationPrivate::notify_helper (this=0xb88820, receiver=0x16ddd70, e=0x7fff16fcb440) at kernel/qapplication.cpp:4061
#16 0x0000003ab39968ce in QApplication::notify (this=<value optimized out>, receiver=0x16ddd70, e=0x7fff16fcb440) at kernel/qapplication.cpp:4030
#17 0x0000003ab4e11a66 in KApplication::notify (this=0xb78510, receiver=0x16ddd70, event=0x7fff16fcb440) at /usr/src/debug/kdelibs-4.3.4/kdeui/kernel/kapplication.cpp:302
#18 0x0000003ab153ee6c in QCoreApplication::notifyInternal (this=0xb78510, receiver=0x16ddd70, event=0x7fff16fcb440) at kernel/qcoreapplication.cpp:610
#19 0x0000003ab39dde7b in sendEvent (event=0x7fff16fcb440, receiver=<value optimized out>) at ../../src/corelib/kernel/qcoreapplication.h:213
#20 QWidget::event (event=0x7fff16fcb440, receiver=<value optimized out>) at kernel/qwidget.cpp:7802
#21 0x0000003ab3d35a16 in QFrame::event (this=0x1667080, e=0x7fff16fcb440) at widgets/qframe.cpp:559
#22 0x0000003ab3dc4211 in QAbstractScrollArea::event (this=0x1667080, e=0x7fff16fcb440) at widgets/qabstractscrollarea.cpp:918
#23 0x0000003ab398f65c in QApplicationPrivate::notify_helper (this=0xb88820, receiver=0x1667080, e=0x7fff16fcb440) at kernel/qapplication.cpp:4065
#24 0x0000003ab39968ce in QApplication::notify (this=<value optimized out>, receiver=0x1667080, e=0x7fff16fcb440) at kernel/qapplication.cpp:4030
#25 0x0000003ab4e11a66 in KApplication::notify (this=0xb78510, receiver=0x1667080, event=0x7fff16fcb440) at /usr/src/debug/kdelibs-4.3.4/kdeui/kernel/kapplication.cpp:302
#26 0x0000003ab153ee6c in QCoreApplication::notifyInternal (this=0xb78510, receiver=0x1667080, event=0x7fff16fcb440) at kernel/qcoreapplication.cpp:610
#27 0x0000003ab3999c3b in sendSpontaneousEvent (event=<value optimized out>, receiver=<value optimized out>) at ../../src/corelib/kernel/qcoreapplication.h:216
#28 QApplication::setActiveWindow (event=<value optimized out>, receiver=<value optimized out>) at kernel/qapplication.cpp:2414
#29 0x0000003ab39fab9b in QApplication::x11ProcessEvent (this=<value optimized out>, event=0x7fff16fccd20) at kernel/qapplication_x11.cpp:3468
#30 0x0000003ab3a2284c in x11EventSourceDispatch (s=<value optimized out>, callback=<value optimized out>, user_data=<value optimized out>) at kernel/qguieventdispatcher_glib.cpp:146
#31 0x0000003aa843922e in g_main_context_dispatch () from /lib64/libglib-2.0.so.0
#32 0x0000003aa843cc18 in ?? () from /lib64/libglib-2.0.so.0
#33 0x0000003aa843cd3a in g_main_context_iteration () from /lib64/libglib-2.0.so.0
#34 0x0000003ab15671e6 in QEventDispatcherGlib::processEvents (this=0xb602b0, flags=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:327
#35 0x0000003ab3a21ffe in QGuiEventDispatcherGlib::processEvents (this=<value optimized out>, flags=<value optimized out>) at kernel/qguieventdispatcher_glib.cpp:202
#36 0x0000003ab153d772 in QEventLoop::processEvents (this=<value optimized out>, flags=...) at kernel/qeventloop.cpp:149
#37 0x0000003ab153db44 in QEventLoop::exec (this=0x7fff16fcd050, flags=...) at kernel/qeventloop.cpp:201
#38 0x0000003ab153fcd9 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:888
#39 0x0000003ab7a3af4f in kdemain () from /usr/lib64/libkdeinit4_plasma-desktop.so
#40 0x0000003aa641eb1d 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=<value optimized out>) at libc-start.c:220
#41 0x0000000000400779 in _start ()

Reported using DrKonqi