Application that crashed: plasma-desktop
Version of the application: 0.3
KDE Version: 4.2.90 (KDE 4.2.90 (KDE 4.3 Beta2))
Qt Version: 4.5.0
Operating System: Linux 2.6.28-13-generic x86_64
Distribution: Ubuntu 9.04

What I was doing when the application crashed:
When I mouse over a folder in the folder view widget on my plasma desktop a bubble pops up with a large red X saying:

Could not open folder /home/user/desktop/foldername

Plasma instanly crashes showing my gnome desktop behind it, then reloads.

I'm using ubuntu / Kubuntu 9.0.4 with KDE 4.2.90

 -- Backtrace:
Application: Plasma Workspace (kdeinit), signal: Segmentation fault
[Current thread is 0 (LWP 4406)]

Thread 2 (Thread 0x7f6593157950 (LWP 4408)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:261
#1  0x00007f65b3de1939 in QWaitCondition::wait (this=0x294f750, mutex=0x294f748, time=18446744073709551615) at thread/qwaitcondition_unix.cpp:87
#2  0x00007f65b2c5e4cc in QHostInfoAgent::run (this=0x294f730) at kernel/qhostinfo.cpp:260
#3  0x00007f65b3de0952 in QThreadPrivate::start (arg=0x294f730) at thread/qthread_unix.cpp:189
#4  0x00007f65afc623ba in start_thread (arg=<value optimized out>) at pthread_create.c:297
#5  0x00007f65b0846fcd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#6  0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7f65b439e750 (LWP 4406)):
[KCrash Handler]
#5  0x00007f65b1a3e3fc in QGraphicsScene::drawItems (this=<value optimized out>, painter=0x7fffbc3dc2e0, numItems=2, items=0x1, options=0x3deaa70, widget=0x3821890)
    at graphicsview/qgraphicsscene.cpp:4867
#6  0x00007f65b1a60260 in QGraphicsView::paintEvent (this=0x2877f90, event=<value optimized out>) at graphicsview/qgraphicsview.cpp:3542
#7  0x00007f65b14a46e6 in QWidget::event (this=0x2877f90, event=0x7fffbc3dca90) at kernel/qwidget.cpp:7654
#8  0x00007f65b183e40b in QFrame::event (this=0x2877f90, e=0x7fffbc3dca90) at widgets/qframe.cpp:559
#9  0x00007f65b1a5ad1b in QGraphicsView::viewportEvent (this=0x2877f90, event=0x7fffbc3dca90) at graphicsview/qgraphicsview.cpp:2933
#10 0x00007f65b3ec8a68 in QCoreApplicationPrivate::sendThroughObjectEventFilters (this=<value optimized out>, receiver=0x3821890, event=0x7fffbc3dca90) at kernel/qcoreapplication.cpp:718
#11 0x00007f65b145375c in QApplicationPrivate::notify_helper (this=0x20f4e70, receiver=0x3821890, e=0x7fffbc3dca90) at kernel/qapplication.cpp:4080
#12 0x00007f65b145b97a in QApplication::notify (this=0x20b3d60, receiver=0x3821890, e=0x7fffbc3dca90) at kernel/qapplication.cpp:4049
#13 0x00007f65b259606b in KApplication::notify (this=0x20b3d60, receiver=0x3821890, event=0x7fffbc3dca90) at /build/buildd/kde4libs-4.2.90/kdeui/kernel/kapplication.cpp:302
#14 0x00007f65b3ec975c in QCoreApplication::notifyInternal (this=0x20b3d60, receiver=0x3821890, event=0x7fffbc3dca90) at kernel/qcoreapplication.cpp:602
#15 0x00007f65b14ab9a5 in QWidgetPrivate::drawWidget (this=0x3bd5960, pdev=0x3be11a8, rgn=@0x7fffbc3dccc0, offset=@0x7fffbc3dccb0, flags=4, sharedPainter=0x0, backingStore=0x3bf5c90)
    at kernel/qwidget.cpp:5046
#16 0x00007f65b14ac117 in QWidgetPrivate::paintSiblingsRecursive (this=0x3c7a200, pdev=0x3be11a8, siblings=@0x3c7a218, index=2, rgn=@0x7fffbc3dcfd0, offset=@0x7fffbc3dcfc0, flags=4, 
    sharedPainter=0x0, backingStore=0x3bf5c90) at kernel/qwidget.cpp:5156
#17 0x00007f65b14ab617 in QWidgetPrivate::drawWidget (this=0x3c7a200, pdev=0x3be11a8, rgn=@0x7fffbc3dcfd0, offset=@0x7fffbc3dcfc0, flags=4, sharedPainter=0x0, backingStore=0x3bf5c90)
    at kernel/qwidget.cpp:5095
#18 0x00007f65b14ac117 in QWidgetPrivate::paintSiblingsRecursive (this=0x3b93360, pdev=0x3be11a8, siblings=@0x3b93378, index=3, rgn=@0x7fffbc3dd440, offset=@0x3bf5cd4, flags=4, sharedPainter=0x0, 
    backingStore=0x3bf5c90) at kernel/qwidget.cpp:5156
#19 0x00007f65b14ab617 in QWidgetPrivate::drawWidget (this=0x3b93360, pdev=0x3be11a8, rgn=@0x7fffbc3dd440, offset=@0x3bf5cd4, flags=4, sharedPainter=0x0, backingStore=0x3bf5c90)
    at kernel/qwidget.cpp:5095
#20 0x00007f65b164f362 in QWidgetBackingStore::sync (this=0x3bf5c90) at painting/qbackingstore.cpp:1266
#21 0x00007f65b149d050 in QWidgetPrivate::syncBackingStore (this=0x3b93360) at kernel/qwidget.cpp:1603
#22 0x00007f65b14a457d in QWidget::event (this=0x3bb18b0, event=0x2a90970) at kernel/qwidget.cpp:7794
#23 0x00007f65b145378d in QApplicationPrivate::notify_helper (this=0x20f4e70, receiver=0x3bb18b0, e=0x2a90970) at kernel/qapplication.cpp:4084
#24 0x00007f65b145b97a in QApplication::notify (this=0x20b3d60, receiver=0x3bb18b0, e=0x2a90970) at kernel/qapplication.cpp:4049
#25 0x00007f65b259606b in KApplication::notify (this=0x20b3d60, receiver=0x3bb18b0, event=0x2a90970) at /build/buildd/kde4libs-4.2.90/kdeui/kernel/kapplication.cpp:302
#26 0x00007f65b3ec975c in QCoreApplication::notifyInternal (this=0x20b3d60, receiver=0x3bb18b0, event=0x2a90970) at kernel/qcoreapplication.cpp:602
#27 0x00007f65b3eca3ca in QCoreApplicationPrivate::sendPostedEvents (receiver=0x0, event_type=0, data=0x205e100) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:213
#28 0x00007f65b3ef31e3 in postEventSourceDispatch (s=<value optimized out>) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:218
#29 0x00007f65afeb120a in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#30 0x00007f65afeb48e0 in ?? () from /usr/lib/libglib-2.0.so.0
#31 0x00007f65afeb4a7c in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#32 0x00007f65b3ef2e6f in QEventDispatcherGlib::processEvents (this=0x20f4300, flags=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:323
#33 0x00007f65b14ebbef in QGuiEventDispatcherGlib::processEvents (this=0x31003200370020, flags=<value optimized out>) at kernel/qguieventdispatcher_glib.cpp:202
#34 0x00007f65b3ec8002 in QEventLoop::processEvents (this=<value optimized out>, flags={i = -1136795952}) at kernel/qeventloop.cpp:149
#35 0x00007f65b3ec83cd in QEventLoop::exec (this=0x7fffbc3ddf10, flags={i = -1136795872}) at kernel/qeventloop.cpp:200
#36 0x00007f65b3eca694 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:880
#37 0x00007f65a7cba7eb in kdemain () from /usr/lib/libkdeinit4_plasma-desktop.so
#38 0x000000000040714e in launch (argc=1, _name=0x20a82b8 "/usr/bin/plasma-desktop", args=<value optimized out>, cwd=0x0, envc=0, envs=0x20a82d8 "", reset_env=false, tty=0x0, avoid_loops=false, 
    startup_id_str=0x40a308 "0") at /build/buildd/kde4libs-4.2.90/kinit/kinit.cpp:671
#39 0x0000000000407978 in handle_launcher_request (sock=7, who=<value optimized out>) at /build/buildd/kde4libs-4.2.90/kinit/kinit.cpp:1163
#40 0x0000000000407f25 in handle_requests (waitForPid=0) at /build/buildd/kde4libs-4.2.90/kinit/kinit.cpp:1356
#41 0x0000000000408a66 in main (argc=2, argv=0x7fffbc3deda8, envp=0x7fffbc3dedc0) at /build/buildd/kde4libs-4.2.90/kinit/kinit.cpp:1783

Reported using DrKonqi