Application that crashed: plasma-desktop
Version of the application: 0.3
KDE Version: 4.3.3 (KDE 4.3.3)
Qt Version: 4.5.2
Operating System: Linux 2.6.31-15-generic i686
Distribution: Ubuntu 9.10

What I was doing when the application crashed:
Plasma-desktop crashed after removing "Media player controls" because it did not work.  
"Media player controls" was rendered as a red X icon.  When trying to remove it (right click -> Remove this...), plasma-desktop crashed.

 -- Backtrace:
Application: Plasma Workspace (kdeinit4), signal: Segmentation fault
[Current thread is 1 (Thread 0xb77b0700 (LWP 2198))]

Thread 2 (Thread 0xaa733b70 (LWP 2202)):
#0  0x00c2a422 in __kernel_vsyscall ()
#1  0x00840e15 in pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/i386/i686/../i486/pthread_cond_wait.S:122
#2  0x007a778d in __pthread_cond_wait (cond=0x95342b8, mutex=0x95342a0) at forward.c:139
#3  0x00973e67 in QWaitConditionPrivate::wait (this=0x9577750, mutex=0x957774c, time=4294967295) at thread/qwaitcondition_unix.cpp:87
#4  QWaitCondition::wait (this=0x9577750, mutex=0x957774c, time=4294967295) at thread/qwaitcondition_unix.cpp:159
#5  0x03266922 in QHostInfoAgent::run (this=0x9577740) at kernel/qhostinfo.cpp:260
#6  0x00972e32 in QThreadPrivate::start (arg=0x9577740) at thread/qthread_unix.cpp:188
#7  0x0083c80e in start_thread (arg=0xaa733b70) at pthread_create.c:300
#8  0x0079a7ee in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:130

Thread 1 (Thread 0xb77b0700 (LWP 2198)):
[KCrash Handler]
#6  QGraphicsLayoutItem::geometry (this=0x10) at graphicsview/qgraphicslayoutitem.cpp:664
#7  0x04b56a4f in QGraphicsWidget::size (this=0x0) at graphicsview/qgraphicswidget.cpp:336
#8  0x057c172b in ?? () from /usr/lib/libkdeinit4_plasma-desktop.so
#9  0x04553dd4 in QWidget::event (this=0xa73ab50, event=0xbf9db244) at kernel/qwidget.cpp:7687
#10 0x044fef54 in QApplicationPrivate::notify_helper (this=0x9172810, receiver=0xa73ab50, e=0xbf9db244) at kernel/qapplication.cpp:4056
#11 0x045065ca in QApplication::notify (this=0x914b980, receiver=0xa73ab50, e=0xbf9db244) at kernel/qapplication.cpp:4021
#12 0x0102b14a in KApplication::notify (this=0x914b980, receiver=0xa73ab50, event=0xbf9db244) at ../../kdeui/kernel/kapplication.cpp:302
#13 0x00a636cb in QCoreApplication::notifyInternal (this=0x914b980, receiver=0xa73ab50, event=0xbf9db244) at kernel/qcoreapplication.cpp:610
#14 0x0455be25 in QCoreApplication::sendSpontaneousEvent (this=0xa73abe8, pdev=0x95a64bc, rgn=..., offset=..., flags=<value optimized out>, sharedPainter=0x0, backingStore=0x957b6f0)
    at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:216
#15 QWidgetPrivate::drawWidget (this=0xa73abe8, pdev=0x95a64bc, rgn=..., offset=..., flags=<value optimized out>, sharedPainter=0x0, backingStore=0x957b6f0) at kernel/qwidget.cpp:5079
#16 0x0455c64d in QWidgetPrivate::paintSiblingsRecursive (this=0x9642a88, pdev=0x95a64bc, siblings=..., index=15, rgn=..., offset=..., flags=4, sharedPainter=0x0, backingStore=0x957b6f0)
    at kernel/qwidget.cpp:5189
#17 0x0455ba16 in QWidgetPrivate::drawWidget (this=0x9642a88, pdev=0x95a64bc, rgn=..., offset=..., flags=<value optimized out>, sharedPainter=0x0, backingStore=0x957b6f0) at kernel/qwidget.cpp:5128
#18 0x046ea2f8 in QWidgetBackingStore::sync (this=0x957b6f0) at painting/qbackingstore.cpp:1269
#19 0x0454d116 in QWidgetPrivate::syncBackingStore (this=0x9642a88) at kernel/qwidget.cpp:1603
#20 0x04554215 in QWidget::event (this=0x9642800, event=0xa6ce510) at kernel/qwidget.cpp:7827
#21 0x04903633 in QFrame::event (this=0x9642800, e=0xa6ce510) at widgets/qframe.cpp:559
#22 0x049a2faa in QAbstractScrollArea::event (this=0x9642800, e=0xa6ce510) at widgets/qabstractscrollarea.cpp:918
#23 0x04b4c406 in QGraphicsView::event (this=0x9642800, event=0xa6ce510) at graphicsview/qgraphicsview.cpp:2840
#24 0x057b8523 in ?? () from /usr/lib/libkdeinit4_plasma-desktop.so
#25 0x044fef54 in QApplicationPrivate::notify_helper (this=0x9172810, receiver=0xa6ce510, e=0x9642800) at kernel/qapplication.cpp:4056
#26 0x045065ca in QApplication::notify (this=0x914b980, receiver=0x9642800, e=0xa6ce510) at kernel/qapplication.cpp:4021
#27 0x0102b14a in KApplication::notify (this=0x914b980, receiver=0x9642800, event=0xa6ce510) at ../../kdeui/kernel/kapplication.cpp:302
#28 0x00a636cb in QCoreApplication::notifyInternal (this=0x914b980, receiver=0x9642800, event=0xa6ce510) at kernel/qcoreapplication.cpp:610
#29 0x00a642b2 in QCoreApplication::sendEvent (receiver=0x0, event_type=0, data=0x90dee48) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:213
#30 QCoreApplicationPrivate::sendPostedEvents (receiver=0x0, event_type=0, data=0x90dee48) at kernel/qcoreapplication.cpp:1247
#31 0x00a6447d in QCoreApplication::sendPostedEvents (receiver=0x0, event_type=0) at kernel/qcoreapplication.cpp:1140
#32 0x00a8e3ff in QCoreApplication::sendPostedEvents (s=0x9174910) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:218
#33 postEventSourceDispatch (s=0x9174910) at kernel/qeventdispatcher_glib.cpp:210
#34 0x00b8fe78 in g_main_context_dispatch () from /lib/libglib-2.0.so.0
#35 0x00b93720 in ?? () from /lib/libglib-2.0.so.0
#36 0x00b93853 in g_main_context_iteration () from /lib/libglib-2.0.so.0
#37 0x00a8e02c in QEventDispatcherGlib::processEvents (this=0x9172600, flags=...) at kernel/qeventdispatcher_glib.cpp:327
#38 0x0459fbe5 in QGuiEventDispatcherGlib::processEvents (this=0x9172600, flags=...) at kernel/qguieventdispatcher_glib.cpp:202
#39 0x00a61c79 in QEventLoop::processEvents (this=0xbf9dc024, flags=) at kernel/qeventloop.cpp:149
#40 0x00a620ca in QEventLoop::exec (this=0xbf9dc024, flags=...) at kernel/qeventloop.cpp:201
#41 0x00a6453f in QCoreApplication::exec () at kernel/qcoreapplication.cpp:888
#42 0x044fedd7 in QApplication::exec () at kernel/qapplication.cpp:3525
#43 0x057ad80d in kdemain () from /usr/lib/libkdeinit4_plasma-desktop.so
#44 0x0804dde1 in launch (argc=<value optimized out>, _name=<value optimized out>, args=<value optimized out>, cwd=0x0, envc=0, envs=0x90f7230 "", reset_env=false, tty=0x0, avoid_loops=false, 
    startup_id_str=0x80511a5 "0") at ../../kinit/kinit.cpp:677
#45 0x0804ea35 in handle_launcher_request (sock=<value optimized out>, who=<value optimized out>) at ../../kinit/kinit.cpp:1169
#46 0x0804eeac in handle_requests (waitForPid=<value optimized out>) at ../../kinit/kinit.cpp:1362
#47 0x0804fbaf in main (argc=2, argv=0xbf9dc884, envp=0xbf9dc890) at ../../kinit/kinit.cpp:1793

Reported using DrKonqi