Application that crashed: plasma-desktop
Version of the application: 0.3
KDE Version: 4.2.85 (KDE 4.2.85 (KDE 4.3 Beta1))
Qt Version: 4.5.1
Operating System: Linux 2.6.30-6-generic i686
Distribution: Ubuntu karmic (development branch)

What I was doing when the application crashed:
"nm-applet" (the Gnome Network Manager) was already started.
I accidentially klicked on /usr/share/app-install/desktop/nm-applet.desktop in the intention to open this file in kate. The taskbar showed a "Network Manager" task that didn't hide (I tried it later again and waited: It gets hidden after some time, but i didn't wait long enough the first time). So I hovered the task and the whole taskbar crashed.
This is reproducable.

KDE 4.2.85 on Kubuntu Karmic

 -- Backtrace:
Application: Plasma Workspace (plasma-desktop), signal: Segmentation fault
[Current thread is 0 (LWP 4547)]

Thread 2 (Thread 0xab7a0b90 (LWP 4550)):
#0  0x00220422 in __kernel_vsyscall ()
#1  0x00cb40e5 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/tls/i686/cmov/libpthread.so.0
#2  0x0062c43d in pthread_cond_wait () from /lib/tls/i686/cmov/libc.so.6
#3  0x03f3f167 in QWaitCondition::wait () from /usr/lib/libQtCore.so.4
#4  0x074fb23a in ?? () from /usr/lib/libQtNetwork.so.4
#5  0x03f3e0fe in ?? () from /usr/lib/libQtCore.so.4
#6  0x00cb04ff in start_thread () from /lib/tls/i686/cmov/libpthread.so.0
#7  0x0061d5ee in clone () from /lib/tls/i686/cmov/libc.so.6

Thread 1 (Thread 0xb71a4720 (LWP 4547)):
[KCrash Handler]
#6  0x018a0f37 in TaskManager::Task::window () from /usr/lib/libtaskmanager.so.4
#7  0x04040caf in QObject::event () from /usr/lib/libQtCore.so.4
#8  0x0930c8a4 in QGraphicsWidget::event () from /usr/lib/libQtGui.so.4
#9  0x08c7dc1c in QApplicationPrivate::notify_helper () from /usr/lib/libQtGui.so.4
#10 0x08c853f4 in QApplication::notify () from /usr/lib/libQtGui.so.4
#11 0x00ec450a in KApplication::notify () from /usr/lib/libkdeui.so.5
#12 0x04030b1b in QCoreApplication::notifyInternal () from /usr/lib/libQtCore.so.4
#13 0x0405e6a6 in ?? () from /usr/lib/libQtCore.so.4
#14 0x0405c050 in ?? () from /usr/lib/libQtCore.so.4
#15 0x06569f68 in IA__g_main_context_dispatch (context=0x9699700) at /build/buildd/glib2.0-2.21.0/glib/gmain.c:1814
#16 0x0656d578 in g_main_context_iterate (context=0x9699700, block=<value optimized out>, dispatch=1, self=0x9695d48) at /build/buildd/glib2.0-2.21.0/glib/gmain.c:2448
#17 0x0656d6ea in IA__g_main_context_iteration (context=0x9699700, may_block=1) at /build/buildd/glib2.0-2.21.0/glib/gmain.c:2511
#18 0x0405bf9c in QEventDispatcherGlib::processEvents () from /usr/lib/libQtCore.so.4
#19 0x08d1f975 in ?? () from /usr/lib/libQtGui.so.4
#20 0x0402f0a9 in QEventLoop::processEvents () from /usr/lib/libQtCore.so.4
#21 0x0402f4f2 in QEventLoop::exec () from /usr/lib/libQtCore.so.4
#22 0x0403187f in QCoreApplication::exec () from /usr/lib/libQtCore.so.4
#23 0x08c7da97 in QApplication::exec () from /usr/lib/libQtGui.so.4
#24 0x0042c94d in kdemain () from /usr/lib/libkdeinit4_plasma-desktop.so
#25 0x080485cb in _start ()