PS: Whoever wrote DrKonqui: You're great!

Correction: it's mostly repeatable, but I have to be really fast to get krunner to die. 

After the first crash it now doesn't show DrKonqui again, though. It just diappears but keeps working (alt-f2 shows it again).

As you can reproduce the crash at will, may you read http://techbase.kde.org/Development/Tutorials/Debugging/How_to_create_useful_crash_reports and post a complete backtrace here? You need to get debug symbols for kdebase-workspace. Thanks

is kdebase-workspace synonymous to kde-base/plasma-workspace?

No, kdebase/workspace includes more things than Plasma. May be the name is kde-base/krunner ?

I ctreated a new backtrace - hopefully with the right debugging symbols. 

For the record: This is how I rebuilt it - I hope I did no error in that: 

$ FLAGS="-march=k8 -O2 -pipe -gddb" CXXFLAGS="${CFLAGS}" FEATURES="nostrip" emerge krunner

Backtrace: 

====== ====== ====== ====== ====== ====== 

Application: Oberfläche zur Ausführung von Befehlen (kdeinit4), signal: Segmentation fault
[Current thread is 0 (LWP 24246)]

Thread 5 (Thread 0x7f8208e2f950 (LWP 24885)):
#0  0x00007f8221e14dc9 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/libpthread.so.0
#1  0x00007f8222082359 in QWaitCondition::wait () from /usr/lib64/qt4/libQtCore.so.4
#2  0x00007f82182b7414 in ?? () from /usr/lib64/libthreadweaver.so.4
#3  0x00007f82182b9b43 in ?? () from /usr/lib64/libthreadweaver.so.4
#4  0x00007f82182b9b5c in ?? () from /usr/lib64/libthreadweaver.so.4
#5  0x00007f82182b8117 in ?? () from /usr/lib64/libthreadweaver.so.4
#6  0x00007f82182b8559 in ThreadWeaver::Thread::run () from /usr/lib64/libthreadweaver.so.4
#7  0x00007f8222081614 in ?? () from /usr/lib64/qt4/libQtCore.so.4
#8  0x00007f8221e11017 in start_thread () from /lib/libpthread.so.0
#9  0x00007f821eaa348d in clone () from /lib/libc.so.6
#10 0x0000000000000000 in ?? ()

Thread 4 (Thread 0x7f820862e950 (LWP 24886)):
#0  0x00007f8221e14dc9 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/libpthread.so.0
#1  0x00007f8222082359 in QWaitCondition::wait () from /usr/lib64/qt4/libQtCore.so.4
#2  0x00007f82182b7414 in ?? () from /usr/lib64/libthreadweaver.so.4
#3  0x00007f82182b9b43 in ?? () from /usr/lib64/libthreadweaver.so.4
#4  0x00007f82182b8117 in ?? () from /usr/lib64/libthreadweaver.so.4
#5  0x00007f82182b8559 in ThreadWeaver::Thread::run () from /usr/lib64/libthreadweaver.so.4
#6  0x00007f8222081614 in ?? () from /usr/lib64/qt4/libQtCore.so.4
#7  0x00007f8221e11017 in start_thread () from /lib/libpthread.so.0
#8  0x00007f821eaa348d in clone () from /lib/libc.so.6
#9  0x0000000000000000 in ?? ()

Thread 3 (Thread 0x7f8207e2d950 (LWP 24887)):
#0  0x00007f8221e14dc9 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/libpthread.so.0
#1  0x00007f8222082359 in QWaitCondition::wait () from /usr/lib64/qt4/libQtCore.so.4
#2  0x00007f82182b7414 in ?? () from /usr/lib64/libthreadweaver.so.4
#3  0x00007f82182b9b43 in ?? () from /usr/lib64/libthreadweaver.so.4
#4  0x00007f82182b9b5c in ?? () from /usr/lib64/libthreadweaver.so.4
#5  0x00007f82182b8117 in ?? () from /usr/lib64/libthreadweaver.so.4
#6  0x00007f82182b8559 in ThreadWeaver::Thread::run () from /usr/lib64/libthreadweaver.so.4
#7  0x00007f8222081614 in ?? () from /usr/lib64/qt4/libQtCore.so.4
#8  0x00007f8221e11017 in start_thread () from /lib/libpthread.so.0
#9  0x00007f821eaa348d in clone () from /lib/libc.so.6
#10 0x0000000000000000 in ?? ()

Thread 2 (Thread 0x7f820762c950 (LWP 24888)):
#0  0x00007f8221e14dc9 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/libpthread.so.0
#1  0x00007f8222082359 in QWaitCondition::wait () from /usr/lib64/qt4/libQtCore.so.4
#2  0x00007f82182b7414 in ?? () from /usr/lib64/libthreadweaver.so.4
#3  0x00007f82182b9b43 in ?? () from /usr/lib64/libthreadweaver.so.4
#4  0x00007f82182b8117 in ?? () from /usr/lib64/libthreadweaver.so.4
#5  0x00007f82182b8559 in ThreadWeaver::Thread::run () from /usr/lib64/libthreadweaver.so.4
#6  0x00007f8222081614 in ?? () from /usr/lib64/qt4/libQtCore.so.4
#7  0x00007f8221e11017 in start_thread () from /lib/libpthread.so.0
#8  0x00007f821eaa348d in clone () from /lib/libc.so.6
#9  0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7f8222603750 (LWP 24246)):
[KCrash Handler]
#5  0x00007f821f6f1b70 in QIcon::QIcon () from /usr/lib64/qt4/libQtGui.so.4
#6  0x00007f821709f3e1 in QuickSand::QsMatchView::showSelected () from /usr/lib64/libkdeinit4_krunner.so
#7  0x00007f821709f991 in QuickSand::QsMatchView::keyPressEvent () from /usr/lib64/libkdeinit4_krunner.so
#8  0x00007f821f6b7973 in QWidget::event () from /usr/lib64/qt4/libQtGui.so.4
#9  0x00007f821f66ab3d in QApplicationPrivate::notify_helper () from /usr/lib64/qt4/libQtGui.so.4
#10 0x00007f821f6743a5 in QApplication::notify () from /usr/lib64/qt4/libQtGui.so.4
#11 0x00007f822063fbbb in KApplication::notify () from /usr/lib64/libkdeui.so.5
#12 0x00007f8222154033 in QCoreApplication::notifyInternal () from /usr/lib64/qt4/libQtCore.so.4
#13 0x00007f821f6ecd64 in ?? () from /usr/lib64/qt4/libQtGui.so.4
#14 0x00007f821f6eede0 in ?? () from /usr/lib64/qt4/libQtGui.so.4
#15 0x00007f821f6cbc0d in QApplication::x11ProcessEvent () from /usr/lib64/qt4/libQtGui.so.4
#16 0x00007f821f6f05a4 in ?? () from /usr/lib64/qt4/libQtGui.so.4
#17 0x00007f821e105fe1 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#18 0x00007f821e1096bd in ?? () from /usr/lib/libglib-2.0.so.0
#19 0x00007f821e10987b in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#20 0x00007f8222178bff in QEventDispatcherGlib::processEvents () from /usr/lib64/qt4/libQtCore.so.4
#21 0x00007f821f6efe6f in ?? () from /usr/lib64/qt4/libQtGui.so.4
#22 0x00007f8222152a32 in QEventLoop::processEvents () from /usr/lib64/qt4/libQtCore.so.4
#23 0x00007f8222152bcc in QEventLoop::exec () from /usr/lib64/qt4/libQtCore.so.4
#24 0x00007f8222154bc4 in QCoreApplication::exec () from /usr/lib64/qt4/libQtCore.so.4
#25 0x00007f821708f04c in kdemain () from /usr/lib64/libkdeinit4_krunner.so
#26 0x0000000000407650 in _start ()

====== ====== ====== ====== ====== ======

It still not complete but it has more information. It looks like bug 183478 (but the reporter said he couldn't reproduce anymore)...

I assume I'd have to recompile larger heaps of KDE to add more information... if it's necessary I can do so, but I'd rather not (will take quite some time). 

I can only reproduce it one time after logging in. Afterwards krunner just dies silently - till I log out and log in again.

If you restart KRunner (with "krunner" on Konsole), it should reappear again.

After a crash it doesn't start from console. 

$ gdb krunner
GNU gdb 6.8               
Copyright (C) 2008 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.           
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"   
and "show warranty" for details.                                             
This GDB was configured as "x86_64-pc-linux-gnu"...                          
(no debugging symbols found)                                                 
(gdb) run                                                                    
Starting program: /usr/bin/krunner                                           
(no debugging symbols found)                                                 
...
(no debugging symbols found)                                                 
[Thread debugging using libthread_db enabled]                                
(no debugging symbols found)                                                 
...
(no debugging symbols found)                                                 
---Type <return> to continue, or q <return> to quit---                       
(no debugging symbols found)                                                 
...
(no debugging symbols found)                                                 
---Type <return> to continue, or q <return> to quit---                       
(no debugging symbols found)                                                 
...
(no debugging symbols found)
[New Thread 0x7ffcb399f760 (LWP 3402)]
---Type <return> to continue, or q <return> to quit---
(no debugging symbols found)
<unknown program name>(3402)/: Communication problem with  "krunner" , it probably crashed.
Error message was:  "org.freedesktop.DBus.Error.NoReply" : " "Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken." "


Program exited with code 0377.
(gdb)

(this is damn crude, though, because I don't know much about gdb)

Marking as duplicate of bug 200648 as it has an updated and complete backtrace.
Thanks

*** This bug has been marked as a duplicate of bug 200648 ***