Application that crashed: plasma-desktop
Version of the application: 0.3
KDE Version: 4.3.2 (KDE 4.3.2)
Qt Version: 4.5.2
Operating System: Linux 2.6.31-14-generic i686
Distribution: Ubuntu 9.10

What I was doing when the application crashed:
Switching between firefox, xemacs and konsole (not sure which two). Not sure if related, but sometimes in minutes prior to crash I believe I've noticed that the the apps in the task bar line forms to thinner lines which do not overlap (e.g. they are thin enough to be placed one over the other, but instead they are stacked horizontally, although one slightly lower than the other) , instead of it's normal display. This only happens to the apps on the taskbar, not any of the other task bar buttons like the K button, the time etc.

I experience this crash about once a day, although less seldom than on jaunty. (I'm on karmic).

 -- Backtrace:
Application: Plasma Workspace (kdeinit4), signal: Segmentation fault
[Current thread is 1 (Thread 0xb7818700 (LWP 2979))]

Thread 2 (Thread 0xac80bb70 (LWP 2980)):
#0  0x0030a422 in __kernel_vsyscall ()
#1  0x0026de15 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/tls/i686/cmov/libpthread.so.0
#2  0x0072378d in pthread_cond_wait () from /lib/tls/i686/cmov/libc.so.6
#3  0x008f1e67 in QWaitConditionPrivate::wait (this=0x9acf4f8, mutex=0x9acf4f4, time=4294967295) at thread/qwaitcondition_unix.cpp:87
#4  QWaitCondition::wait (this=0x9acf4f8, mutex=0x9acf4f4, time=4294967295) at thread/qwaitcondition_unix.cpp:159
#5  0x00dd3922 in QHostInfoAgent::run (this=0x9acf4e8) at kernel/qhostinfo.cpp:260
#6  0x008f0e32 in QThreadPrivate::start (arg=0x9acf4e8) at thread/qthread_unix.cpp:188
#7  0x0026980e in start_thread () from /lib/tls/i686/cmov/libpthread.so.0
#8  0x007167ee in clone () from /lib/tls/i686/cmov/libc.so.6

Thread 1 (Thread 0xb7818700 (LWP 2979)):
[KCrash Handler]
#6  0x01ae925a in QGraphicsLayoutItem::parentLayoutItem (this=0x9a65630) at graphicsview/qgraphicslayoutitem.cpp:762
#7  0x01b040a7 in QGraphicsGridLayout::addItem (this=0x99ede78, item=0xa682468, row=174597224, column=161895984, rowSpan=1, columnSpan=1, alignment=...) at graphicsview/qgraphicsgridlayout.cpp:158
#8  0x01fcc74a in ?? () from /usr/lib/kde4/plasma_applet_tasks.so
#9  0x01fcce2a in ?? () from /usr/lib/kde4/plasma_applet_tasks.so
#10 0x01fcd00f in ?? () from /usr/lib/kde4/plasma_applet_tasks.so
#11 0x01fd9fa2 in ?? () from /usr/lib/kde4/plasma_applet_tasks.so
#12 0x01fda627 in ?? () from /usr/lib/kde4/plasma_applet_tasks.so
#13 0x009f7263 in QMetaObject::activate (sender=0x9a888a8, from_signal_index=21, to_signal_index=21, argv=0xbf96ef88) at kernel/qobject.cpp:3113
#14 0x009f7ec2 in QMetaObject::activate (sender=0x9a888a8, m=0x201abf4, local_signal_index=0, argv=0xbf96ef88) at kernel/qobject.cpp:3187
#15 0x0200c433 in TaskManager::TaskGroup::itemAdded(TaskManager::AbstractGroupableItem*) () from /usr/lib/libtaskmanager.so.4
#16 0x0200ce8b in TaskManager::TaskGroup::add(TaskManager::AbstractGroupableItem*) () from /usr/lib/libtaskmanager.so.4
#17 0x01ffa2cd in ?? () from /usr/lib/libtaskmanager.so.4
#18 0x01ff4002 in ?? () from /usr/lib/libtaskmanager.so.4
#19 0x01ff4a45 in ?? () from /usr/lib/libtaskmanager.so.4
#20 0x01ff63be in TaskManager::GroupManager::qt_metacall(QMetaObject::Call, int, void**) () from /usr/lib/libtaskmanager.so.4
#21 0x009f7263 in QMetaObject::activate (sender=0x9a32298, from_signal_index=4, to_signal_index=4, argv=0x0) at kernel/qobject.cpp:3113
#22 0x009f7ec2 in QMetaObject::activate (sender=0x9a32298, m=0xad2904, local_signal_index=0, argv=0x0) at kernel/qobject.cpp:3187
#23 0x00a31667 in QTimer::timeout (this=0x9a32298) at .moc/release-shared/moc_qtimer.cpp:128
#24 0x009fc9ae in QTimer::timerEvent (this=0x9a32298, e=0xbf96f680) at kernel/qtimer.cpp:261
#25 0x009f13bf in QObject::event (this=0x9a32298, e=0xbf96f680) at kernel/qobject.cpp:1075
#26 0x01494f54 in QApplicationPrivate::notify_helper (this=0x9871870, receiver=0x9a32298, e=0xbf96f680) at kernel/qapplication.cpp:4056
#27 0x0149c67c in QApplication::notify (this=0x984a9e0, receiver=0x9a32298, e=0xbf96f680) at kernel/qapplication.cpp:3603
#28 0x011b4bfa in KApplication::notify (this=0x984a9e0, receiver=0x9a32298, event=0xbf96f680) at ../../kdeui/kernel/kapplication.cpp:302
#29 0x009e16cb in QCoreApplication::notifyInternal (this=0x984a9e0, receiver=0x9a32298, event=0xbf96f680) at kernel/qcoreapplication.cpp:610
#30 0x00a0e7ce in QCoreApplication::sendEvent (this=0x9874434) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:213
#31 QTimerInfoList::activateTimers (this=0x9874434) at kernel/qeventdispatcher_unix.cpp:572
#32 0x00a0c0e0 in timerSourceDispatch (source=0x9874400) at kernel/qeventdispatcher_glib.cpp:165
#33 0x0058be78 in g_main_context_dispatch () from /lib/libglib-2.0.so.0
#34 0x0058f720 in ?? () from /lib/libglib-2.0.so.0
#35 0x0058f853 in g_main_context_iteration () from /lib/libglib-2.0.so.0
#36 0x00a0c02c in QEventDispatcherGlib::processEvents (this=0x9871660, flags=...) at kernel/qeventdispatcher_glib.cpp:327
#37 0x01535be5 in QGuiEventDispatcherGlib::processEvents (this=0x9871660, flags=...) at kernel/qguieventdispatcher_glib.cpp:202
#38 0x009dfc79 in QEventLoop::processEvents (this=0xbf96f944, flags=) at kernel/qeventloop.cpp:149
#39 0x009e00ca in QEventLoop::exec (this=0xbf96f944, flags=...) at kernel/qeventloop.cpp:201
#40 0x009e253f in QCoreApplication::exec () at kernel/qcoreapplication.cpp:888
#41 0x01494dd7 in QApplication::exec () at kernel/qapplication.cpp:3525
#42 0x040d980d in kdemain () from /usr/lib/libkdeinit4_plasma-desktop.so
#43 0x0804dde1 in launch (argc=<value optimized out>, _name=<value optimized out>, args=<value optimized out>, cwd=0x0, envc=0, envs=0x9837198 "", reset_env=false, tty=0x0, avoid_loops=false, 
    startup_id_str=0x80511a5 "0") at ../../kinit/kinit.cpp:677
#44 0x0804ea35 in handle_launcher_request (sock=<value optimized out>, who=<value optimized out>) at ../../kinit/kinit.cpp:1169
#45 0x0804eeac in handle_requests (waitForPid=<value optimized out>) at ../../kinit/kinit.cpp:1362
#46 0x0804fbaf in main (argc=2, argv=0xbf9701a4, envp=0xbf9701b0) at ../../kinit/kinit.cpp:1793

Reported using DrKonqi