and i should note i'm using kde4.0.1 from archlinux (kdemod4)

i can not reproduce this with trunk/ no matter how hard i try =/

anyone else?

Hm, I am not 100% sure, but I think I just experienced this bug (kdelibs r772899, kdebase r772956, no compositing). I added several widgets and then subsequently removed them until I only had the analog clock and the application launcher menu widget left. As I then removed the application launcher menu, plasma crashed with the following backtrace:

Application: Plasma Workspace (plasma), signal SIGSEGV
Using host libthread_db library "/lib/libthread_db.so.1".
[Thread debugging using libthread_db enabled]
[New Thread 0xb62736e0 (LWP 10344)]
[New Thread 0xb4b11b90 (LWP 10345)]
[KCrash handler]
#6  QTimer::stop (this=0x0) at kernel/qtimer.cpp:244
#7  0xb7e6533b in Plasma::AppletHandle::startFading (this=0x85ab348, 
    anim=Plasma::AppletHandle::FadeIn)
    at /var/tmp/portage/kde-base/kdebase-9999.4/work/kdebase-9999.4/workspace/libs/plasma/applethandle.cpp:619
#8  0xb7e7200b in Plasma::Containment::sceneEventFilter (this=0x8137a68, 
    watched=0x81e42c0, event=0xbfb7da10)
    at /var/tmp/portage/kde-base/kdebase-9999.4/work/kdebase-9999.4/workspace/libs/plasma/containment.cpp:831
#9  0xb700a34c in QGraphicsScenePrivate::filterEvent (this=0x8107d28, 
    item=0x81e42c0, event=0xbfb7da10) at graphicsview/qgraphicsscene.cpp:716
#10 0xb700a3a5 in QGraphicsScenePrivate::sendEvent (this=0x8107d28, 
    item=0x81e42c0, event=0xbfb7da10) at graphicsview/qgraphicsscene.cpp:728
#11 0xb700ae21 in QGraphicsScenePrivate::sendHoverEvent (this=0x8107d28, 
    type=QEvent::GraphicsSceneHoverEnter, item=0x81e42c0, 
    hoverEvent=0xbfb7db30) at graphicsview/qgraphicsscene.cpp:773
#12 0xb7010b01 in QGraphicsScenePrivate::dispatchHoverEvent (this=0x8107d28, 
    hoverEvent=0xbfb7db30) at graphicsview/qgraphicsscene.cpp:2901
#13 0xb7010ea4 in QGraphicsScene::event (this=0x8110f80, event=0xbfb7df80)
    at graphicsview/qgraphicsscene.cpp:2555
#14 0xb6a7ce8a in QApplicationPrivate::notify_helper (this=0x8075080, 
    receiver=0x8110f80, e=0xbfb7df80) at kernel/qapplication.cpp:3556
#15 0xb6a7e77a in QApplication::notify (this=0x8057118, receiver=0x8110f80, 
    e=0xbfb7df80) at kernel/qapplication.cpp:3115
#16 0xb7998763 in KApplication::notify (this=0x8057118, receiver=0x8110f80, 
    event=0xbfb7df80)
    at /var/tmp/portage/kde-base/kdelibs-9999.4/work/kdelibs-9999.4/kdeui/kernel/kapplication.cpp:311
#17 0xb73dbd7b in QCoreApplication::notifyInternal (this=0x8057118, 
    receiver=0x8110f80, event=0xbfb7df80) at kernel/qcoreapplication.cpp:530
#18 0xb7027753 in QGraphicsView::mouseMoveEvent (this=0x80ff908, 
    event=0xbfb7e6d4)
    at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:200
#19 0xb6acf7cf in QWidget::event (this=0x80ff908, event=0xbfb7e6d4)
    at kernel/qwidget.cpp:6123
#20 0xb6e12073 in QFrame::event (this=0x80ff908, e=0xbfb7e6d4)
    at widgets/qframe.cpp:655
#21 0xb6eaa7ec in QAbstractScrollArea::viewportEvent (this=0xbfb7d874, e=0x0)
    at widgets/qabstractscrollarea.cpp:924
#22 0xb70223a2 in QGraphicsView::viewportEvent (this=0x80ff908, 
    event=0xbfb7e6d4) at graphicsview/qgraphicsview.cpp:2338
#23 0xb6eac6b2 in QAbstractScrollAreaFilter::eventFilter (this=0x816b130, 
    o=0x8165ae8, e=0xbfb7e6d4) at widgets/qabstractscrollarea_p.h:93
#24 0xb6a7cd9b in QApplicationPrivate::notify_helper (this=0x8075080, 
    receiver=0x8165ae8, e=0xbfb7e6d4) at kernel/qapplication.cpp:3548
#25 0xb6a7ea2c in QApplication::notify (this=0x8057118, receiver=0x8165ae8, 
    e=0xbfb7e6d4) at kernel/qapplication.cpp:3255
#26 0xb7998763 in KApplication::notify (this=0x8057118, receiver=0x8165ae8, 
    event=0xbfb7e6d4)
    at /var/tmp/portage/kde-base/kdelibs-9999.4/work/kdelibs-9999.4/kdeui/kernel/kapplication.cpp:311
#27 0xb73dbd7b in QCoreApplication::notifyInternal (this=0x8057118, 
    receiver=0x8165ae8, event=0xbfb7e6d4) at kernel/qcoreapplication.cpp:530
#28 0xb6ae2628 in QETWidget::translateMouseEvent (this=0x8165ae8, 
    event=0xbfb7ea98)
    at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:203
#29 0xb6ae0e8e in QApplication::x11ProcessEvent (this=0x8057118, 
    event=0xbfb7ea98) at kernel/qapplication_x11.cpp:2913
#30 0xb6b06c45 in QEventDispatcherX11::processEvents (this=0x8074a80, 
    flags=@0xbfb7eb84) at kernel/qeventdispatcher_x11.cpp:125
#31 0xb73db191 in QEventLoop::processEvents (this=0xbfb7ebf0, 
    flags=@0xbfb7ebb8) at kernel/qeventloop.cpp:140
#32 0xb73db29a in QEventLoop::exec (this=0xbfb7ebf0, flags=@0xbfb7ebf8)
    at kernel/qeventloop.cpp:186
#33 0xb73dd626 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:759
#34 0xb6a7c487 in QApplication::exec () at kernel/qapplication.cpp:3053
#35 0xb7f59d54 in kdemain (argc=1, argv=0xbfb7edf4)
    at /var/tmp/portage/kde-base/kdebase-9999.4/work/kdebase-9999.4/workspace/plasma/plasma/main.cpp:54
#36 0x080487e2 in main (argc=138759800, argv=0x8436b68)
    at /var/tmp/portage/kde-base/kdebase-9999.4/work/kdebase_build/workspace/plasma/plasma/plasma-qgv_dummy.cpp:3
#37 0xb6505fdc in __libc_start_main (main=0x80487c0 <main>, argc=1, 
    ubp_av=0xbfb7edf4, init=0x8048810 <__libc_csu_init>, 
    fini=0x8048800 <__libc_csu_fini>, rtld_fini=0xb7f74100 <_dl_fini>, 
    stack_end=0xbfb7edec) at libc-start.c:229
#38 0x08048731 in _start ()
#0  0xffffe410 in __kernel_vsyscall ()

*** This bug has been marked as a duplicate of 157647 ***

Aaron, I am not a Plasma developer, but are you sure that this really is the same as bug #157647? To me the backtraces look pretty different, and the way to "reproduce" (this bug isn't reproducible for me so far) the bugs is differnt.

Oliver Putz, that seems to be quite the same bug as mine that you posted above

note how the this pointer of the QTimer is null, pointing us to the fact that the object that created it already deleted and nullified the pointer.

Oliver: yes, i'm sure it's the same crash. or at least, the same thing causing it. i even know where in the code the crash is coming from. =) i've discussed it with Chani on irc and hopefully we'll have a solution forthcoming soon.