Application that crashed: plasma-desktop
Version of the application: 0.3
KDE Version: 4.2.95 (KDE 4.2.95 (KDE 4.3 RC1))
Qt Version: 4.5.0
Operating System: Linux 2.6.28-13-generic i686
Distribution: Ubuntu 9.04

What I was doing when the application crashed:
I was working in konqueror with that and dolphin open. I noticed the whole thing was running a bit slowly, so I switched to tty1 (ctrl + alt + f1) to run htop. When I switched back (ctrl + alt + F7), plasma was gone, and the crash wizard came up.

And sorry I haven't got the debugging info, but I didn't want to download 200MB of data on my slow connection just for one crash. If it happens again and/or I get free time I'll probably do it.

 -- Backtrace:
Application: Plasma Workspace (kdeinit4), signal: Segmentation fault
[Current thread is 0 (LWP 4664)]

Thread 2 (Thread 0xa92c9b90 (LWP 4695)):
#0  0xb7f45430 in __kernel_vsyscall ()
#1  0xb640b0e5 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/tls/i686/cmov/libpthread.so.0
#2  0xb65eb2ed in pthread_cond_wait () from /lib/tls/i686/cmov/libc.so.6
#3  0xb7d3e9b2 in QWaitCondition::wait () from /usr/lib/libQtCore.so.4
#4  0xb767a152 in ?? () from /usr/lib/libQtNetwork.so.4
#5  0xb7d3d96e in ?? () from /usr/lib/libQtCore.so.4
#6  0xb64074ff in start_thread () from /lib/tls/i686/cmov/libpthread.so.0
#7  0xb65dc49e in clone () from /lib/tls/i686/cmov/libc.so.6

Thread 1 (Thread 0xb5f15a10 (LWP 4664)):
[KCrash Handler]
#6  0xa950332a in TaskManager::GroupManager::manualSortingRequest () from /usr/lib/libtaskmanager.so.4
#7  0xa950131b in TaskManager::AbstractGroupingStrategy::closeGroup () from /usr/lib/libtaskmanager.so.4
#8  0xa9508f27 in ?? () from /usr/lib/libtaskmanager.so.4
#9  0xa9509e5b in ?? () from /usr/lib/libtaskmanager.so.4
#10 0xb7e47ca8 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#11 0xb7e48932 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#12 0xa951cd83 in TaskManager::TaskGroup::itemRemoved () from /usr/lib/libtaskmanager.so.4
#13 0xa951d7ab in TaskManager::TaskGroup::remove () from /usr/lib/libtaskmanager.so.4
#14 0xa9503ba5 in ?? () from /usr/lib/libtaskmanager.so.4
#15 0xa950646a in TaskManager::GroupManager::qt_metacall () from /usr/lib/libtaskmanager.so.4
#16 0xb7e47ca8 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#17 0xb7e48932 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#18 0xa9520823 in TaskManager::TaskManager::taskRemoved () from /usr/lib/libtaskmanager.so.4
#19 0xa95220cf in TaskManager::TaskManager::windowRemoved () from /usr/lib/libtaskmanager.so.4
#20 0xa9523fec in TaskManager::TaskManager::qt_metacall () from /usr/lib/libtaskmanager.so.4
#21 0xb7e47ca8 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#22 0xb7e48932 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#23 0xb7548853 in KWindowSystem::windowRemoved () from /usr/lib/libkdeui.so.5
#24 0xb754b0d6 in ?? () from /usr/lib/libkdeui.so.5
#25 0xb755a753 in NETRootInfo::update () from /usr/lib/libkdeui.so.5
#26 0xb755ab3f in NETRootInfo::event () from /usr/lib/libkdeui.so.5
#27 0xb754b36d in ?? () from /usr/lib/libkdeui.so.5
#28 0xb73fb6f9 in KApplication::x11EventFilter () from /usr/lib/libkdeui.so.5
#29 0xb4a83e37 in ?? () from /usr/lib/libkdeinit4_plasma-desktop.so
#30 0xb6924f3e in ?? () from /usr/lib/libQtGui.so.4
#31 0xb69376a8 in QApplication::x11ProcessEvent () from /usr/lib/libQtGui.so.4
#32 0xb6963c6a in ?? () from /usr/lib/libQtGui.so.4
#33 0xb6454b88 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#34 0xb64580eb in ?? () from /usr/lib/libglib-2.0.so.0
#35 0xb6458268 in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#36 0xb7e5d438 in QEventDispatcherGlib::processEvents () from /usr/lib/libQtCore.so.4
#37 0xb6963365 in ?? () from /usr/lib/libQtGui.so.4
#38 0xb7e3006a in QEventLoop::processEvents () from /usr/lib/libQtCore.so.4
#39 0xb7e304aa in QEventLoop::exec () from /usr/lib/libQtCore.so.4
#40 0xb7e32959 in QCoreApplication::exec () from /usr/lib/libQtCore.so.4
#41 0xb68c1d17 in QApplication::exec () from /usr/lib/libQtGui.so.4
#42 0xb4a6e510 in kdemain () from /usr/lib/libkdeinit4_plasma-desktop.so
#43 0x0804e1c0 in _start ()

Reported using DrKonqi