can you install the debug package for kdebase-workspace and reproduce, so i can see which (of two possible places) in the system tray this is happening? thanks :)

Created attachment 47443 [details]
New crash information added by DrKonqi

As requested, crash after  kdebase-workspace-dbg package installed

 -- Backtrace:
Application: Plasma Workspace (plasma-desktop), signal: Segmentation fault
[KCrash Handler]
#6  QWidget::mapToParent (this=0x0, pos=...) at kernel/qwidget.cpp:3997
#7  0xb5d21eab in QWidget::mapTo (this=0x0, parent=0x9324e00, pos=...) at kernel/qwidget.cpp:3953
#8  0xa631f786 in SystemTray::X11EmbedPainter::performUpdates (this=0x9092f90) at ../../../../../plasma/generic/applets/systemtray/protocols/fdo/x11embedpainter.cpp:127
#9  0xa631fbd1 in SystemTray::X11EmbedPainter::qt_metacall (this=0x9092f90, _c=QMetaObject::InvokeMetaMethod, _id=4, _a=0xbf95fa9c) at ./x11embedpainter.moc:75
#10 0xb59edb2a in QMetaObject::metacall (object=0x9092f90, cl=3214276808, idx=4, argv=0xbf95fa9c) at kernel/qmetaobject.cpp:237
#11 0xb59fc0f5 in QMetaObject::activate (sender=0x91c3084, m=0xb5afb704, local_signal_index=0, argv=0x0) at kernel/qobject.cpp:3293
#12 0xb5a4d967 in QTimer::timeout (this=0x91c3084) at .moc/release-shared/moc_qtimer.cpp:134
#13 0xb5a0437e in QTimer::timerEvent (this=0x91c3084, e=0xbf95ffd0) at kernel/qtimer.cpp:271
#14 0xb59f8f74 in QObject::event (this=0x91c3084, e=0x0) at kernel/qobject.cpp:1212
#15 0xb5cd1bec in QApplicationPrivate::notify_helper (this=0x8d5dd68, receiver=0x91c3084, e=0xbf95ffd0) at kernel/qapplication.cpp:4300
#16 0xb5cd875e in QApplication::notify (this=0x8d4f5f8, receiver=0x91c3084, e=0xbf95ffd0) at kernel/qapplication.cpp:3704
#17 0xb6a507da in KApplication::notify (this=0x8d4f5f8, receiver=0x91c3084, event=0xbf95ffd0) at ../../kdeui/kernel/kapplication.cpp:302
#18 0xb59e892b in QCoreApplication::notifyInternal (this=0x8d4f5f8, receiver=0x91c3084, event=0xbf95ffd0) at kernel/qcoreapplication.cpp:704
#19 0xb5a17986 in QCoreApplication::sendEvent (this=0x8d606cc) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:215
#20 QTimerInfoList::activateTimers (this=0x8d606cc) at kernel/qeventdispatcher_unix.cpp:603
#21 0xb5a14644 in timerSourceDispatch (source=0x8d60698) at kernel/qeventdispatcher_glib.cpp:184
#22 0xb3e5e2f5 in g_main_context_dispatch () from /lib/libglib-2.0.so.0
#23 0xb3e61fd8 in ?? () from /lib/libglib-2.0.so.0
#24 0xb3e621b8 in g_main_context_iteration () from /lib/libglib-2.0.so.0
#25 0xb5a14335 in QEventDispatcherGlib::processEvents (this=0x8d20bc8, flags=...) at kernel/qeventdispatcher_glib.cpp:412
#26 0xb5d90255 in QGuiEventDispatcherGlib::processEvents (this=0x8d20bc8, flags=...) at kernel/qguieventdispatcher_glib.cpp:204
#27 0xb59e6f49 in QEventLoop::processEvents (this=0xbf960294, flags=) at kernel/qeventloop.cpp:149
#28 0xb59e739a in QEventLoop::exec (this=0xbf960294, flags=...) at kernel/qeventloop.cpp:201
#29 0xb59eb52f in QCoreApplication::exec () at kernel/qcoreapplication.cpp:981
#30 0xb5cd1c87 in QApplication::exec () at kernel/qapplication.cpp:3579
#31 0xb76ecfae in kdemain (argc=1, argv=0xbf960474) at ../../../../plasma/desktop/shell/main.cpp:112
#32 0x0804861b in main (argc=1, argv=0xbf960474) at plasma-desktop_dummy.cpp:3

*** This bug has been marked as a duplicate of bug 201620 ***

*** Bug 243943 has been marked as a duplicate of this bug. ***

Created attachment 53205 [details]
New crash information added by DrKonqi

plasma-desktop (0.3) on KDE Platform 4.5.1 (KDE 4.5.1) using Qt 4.7.0

- Custom settings of the application:
The crash of plasma happened when I was using NVIDIA X Server Setting to active the twinview of an external monitor (different size and resolution). However, there is no problem for continue to use the problem. But a minor problem is that when I change back to one monitor settings, the task bar is not properly set to the current monitor.

-- Backtrace (Reduced):
#6  QWidget::mapToParent (this=0x0, pos=...) at kernel/qwidget.cpp:4148
#7  0x00007fe79670ca8b in QWidget::mapTo (this=<value optimized out>, parent=0x1885e70, pos=...) at kernel/qwidget.cpp:4104
#8  0x00007fe77b050e3c in SystemTray::X11EmbedPainter::performUpdates (this=<value optimized out>) at ../../../../../plasma/generic/applets/systemtray/protocols/fdo/x11embedpainter.cpp:134
#9  0x00007fe77b051558 in SystemTray::X11EmbedPainter::qt_metacall (this=0x146b8b0, _c=QMetaObject::InvokeMetaMethod, _id=<value optimized out>, _a=0x7fffaa179ba0) at ./x11embedpainter.moc:75
[...]
#11 0x00007fe79758b8f9 in QObject::event (this=0x1c07988, e=0x7fffaa179830) at kernel/qobject.cpp:1183