This reminds me of bug 179729 which was a Gentoo distribution problem (build/packaging issue)
- Are all your packages up to date ?
Thanks

I am now using 4.3.1-341.1 version of kdebase4-workspace and the problem STILL exists. KDE v4 is from: http://download.opensuse.org/repositories/KDE:/KDE4:/Factory:/Desktop/openSUSE_11.1/

It seems this is just x86_64 bug.
I have other machine running SAME openSuSE version, and SAME KDE version, but locking works like a charm, though X server here is Xorg.

The problem occures on 64bit terminal server, with Sun's Xnewt X server (SunRAY access). KDEv3 worked. KDE v4 ALSO worked.
Can't say for sure on which version this crash appeared.

New crash info after upgrade:
Application: KDE Screen Locker (kscreenlocker), signal: Segmentation fault
[KCrash Handler]
#5  0x00007f915687c4ef in xkl_process_error () from /usr/lib64/libxklavier.so.12
#6  0x00007f9161f29b94 in _XError () from /usr/lib64/libX11.so.6
#7  0x00007f9161f30f19 in ?? () from /usr/lib64/libX11.so.6
#8  0x00007f9161f31600 in _XReply () from /usr/lib64/libX11.so.6
#9  0x00007f9161f13bf2 in XInternAtom () from /usr/lib64/libX11.so.6
#10 0x00007f915687bf6d in ?? () from /usr/lib64/libxklavier.so.12
#11 0x00007f915663d5a0 in g_object_newv () from /usr/lib64/libgobject-2.0.so.0
#12 0x00007f915663e00b in g_object_new_valist () from /usr/lib64/libgobject-2.0.so.0
#13 0x00007f915663e25c in g_object_new () from /usr/lib64/libgobject-2.0.so.0
#14 0x00007f915687bde0 in xkl_engine_get_instance () from /usr/lib64/libxklavier.so.12
#15 0x00007f9156aa468c in XKlavierAdaptor (this=0x7df8d0, dpy=0x6513a0) at /usr/src/debug/kdebase-workspace-4.3.1/kcontrol/kxkb/xklavier_adaptor.cpp:62
#16 0x00007f9156aa48a0 in XKlavierAdaptor::getInstance (dpy=0x6513a0) at /usr/src/debug/kdebase-workspace-4.3.1/kcontrol/kxkb/xklavier_adaptor.cpp:293
#17 0x00007f9156a98cc6 in XkbRules::loadNewRules (this=0x6f5dc0, layoutsOnly=false) at /usr/src/debug/kdebase-workspace-4.3.1/kcontrol/kxkb/rules.cpp:77
#18 0x00007f9156aa8977 in KxkbCore::settingsRead (this=0x896fd0) at /usr/src/debug/kdebase-workspace-4.3.1/kcontrol/kxkb/kxkbcore.cpp:213
#19 0x00007f9156aa8a1d in KxkbCore::newInstance (this=0x896fd0) at /usr/src/debug/kdebase-workspace-4.3.1/kcontrol/kxkb/kxkbcore.cpp:109
#20 0x00007f9156aad90d in KxkbPart (this=0x863620, parent=<value optimized out>, args=<value optimized out>) at /usr/src/debug/kdebase-workspace-4.3.1/kcontrol/kxkb/kxkb_part.cpp:51
#21 0x00007f9156aae275 in KPluginFactory::createInstance<KxkbPart, QWidget> (parentWidget=<value optimized out>, parent=<value optimized out>, args=@0x7fff35833660)
    at /usr/include/kpluginfactory.h:461
#22 0x00007f9160b8740d in KPluginFactory::create(char const*, QWidget*, QObject*, QList<QVariant> const&, QString const&) () from /usr/lib64/libkdecore.so.5
#23 0x000000000041c4bc in PasswordDlg (this=0x7fff358338e0, parent=<value optimized out>, plugin=<value optimized out>, text=@0x7fff35833b60) at /usr/include/kpluginfactory.h:491
#24 0x0000000000414d36 in LockProcess::checkPass (this=0x7fff35835a20) at /usr/src/debug/kdebase-workspace-4.3.1/krunner/lock/lockprocess.cc:1129
#25 0x0000000000416933 in LockProcess::x11Event (this=0x7fff35835a20, event=0x7fff35835820) at /usr/src/debug/kdebase-workspace-4.3.1/krunner/lock/lockprocess.cc:1311
#26 0x00007f916284e443 in KApplication::x11EventFilter(_XEvent*) () from /usr/lib64/libkdeui.so.5
#27 0x00007f915f4bdd2f in ?? () from /usr/lib64/libQtGui.so.4
#28 0x00007f915f4d1224 in QApplication::x11ProcessEvent(_XEvent*) () from /usr/lib64/libQtGui.so.4
#29 0x00007f915f4fa1ff in ?? () from /usr/lib64/libQtGui.so.4
#30 0x00007f91604341d2 in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib64/libQtCore.so.4
#31 0x00007f91604345a4 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib64/libQtCore.so.4
#32 0x00007f9160436894 in QCoreApplication::exec() () from /usr/lib64/libQtCore.so.4
#33 0x000000000042112a in main (argc=<value optimized out>, argv=0x7fff35836068) at /usr/src/debug/kdebase-workspace-4.3.1/krunner/lock/main.cc:173

It took me a bit of time to figure this out.

Basically the crash is the fault of libxklavier or X11 underneath it.  (You can see that after libxklavier calls XInternAtom that it eventually receives an XError for its trouble).

Where is the XInternAtom?  Probably in the xkl_engine_constructor() function.  (This function would be called indirectly by GObject in the g_object_new() call in xkl_engine_get_instance()).

Without more information in libxklavier (i.e. debug symbols) it's hard to say why this is going on, but all that the XKLavierAdaptor is doing in this case is creating a new xkl_engine instance by passing a Display* so I don't think it's an issue with C/C++ differences regarding pointer handling.

Make sure your libxklavier is up to date, as well as your xorg-server and libX11.  If you continue to get these crashes make sure you enable debug symbols for libxklavier before making further backtraces because that's where the crashes are occuring.

I don't believe this is a KDE bug, so closing.  If it turns out to be libxklavier, that is maintained by the GNOME project from what I can tell.

*** Bug 212729 has been marked as a duplicate of this bug. ***