Application: kwin (4.8.5 (4.8.5))
KDE Platform Version: 4.8.5 (4.8.5)
Qt Version: 4.8.1
Operating System: Linux 3.0.0-23-generic x86_64
Distribution: Ubuntu 12.04.1 LTS

-- Information about the crash:
just run apt-get upgrade on kubuntu precise and got this issue
I found similar bugs, but not really same
it works fine if i use only one screen, and fails when trying to connect second one

The crash can be reproduced every time.

-- Backtrace:
Application: KWin (kwin), signal: Segmentation fault
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[Current thread is 1 (Thread 0x7fc0aa515780 (LWP 4030))]

Thread 3 (Thread 0x7fc08e4c9700 (LWP 4032)):
#0  0xffffffffff60017b in ?? ()
#1  0x00007fc08e4c8c10 in ?? ()
#2  0x00007fff6f5ff7e7 in ?? ()
Backtrace stopped: previous frame identical to this frame (corrupt stack?)

Thread 2 (Thread 0x7fc08dcc8700 (LWP 4033)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:162
#1  0x00007fc0a67dc222 in ?? () from /usr/lib/x86_64-linux-gnu/libQtScript.so.4
#2  0x00007fc0a67dc259 in ?? () from /usr/lib/x86_64-linux-gnu/libQtScript.so.4
#3  0x00007fc09e616e9a in start_thread (arg=0x7fc08dcc8700) at pthread_create.c:308
#4  0x00007fc0a9d27cbd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#5  0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7fc0aa515780 (LWP 4030)):
[KCrash Handler]
#6  __GI___libc_free (mem=0x1) at malloc.c:2968
#7  0x00007fc0a7768819 in XFree () from /usr/lib/x86_64-linux-gnu/libX11.so.6
#8  0x00007fc0a73102ee in XRRUpdateConfiguration () from /usr/lib/x86_64-linux-gnu/libXrandr.so.2
#9  0x00007fc0aa05fc60 in KWin::Workspace::workspaceEvent (this=0x1d37a50, e=0x7fff6f4ebda0) at ../../kwin/events.cpp:460
#10 0x00007fc0aa0514b8 in KWin::Application::x11EventFilter (this=0x7fff6f4ec0b0, e=0x7fff6f4ebda0) at ../../kwin/main.cpp:359
#11 0x00007fc0a48e2b85 in qt_x11EventFilter (ev=0x7fff6f4ebda0) at kernel/qapplication_x11.cpp:441
#12 qt_x11EventFilter (ev=0x7fff6f4ebda0) at kernel/qapplication_x11.cpp:429
#13 0x00007fc0a48f1f98 in QApplication::x11ProcessEvent (this=0x7fff6f4ec0b0, event=0x7fff6f4ebda0) at kernel/qapplication_x11.cpp:3444
#14 0x00007fc0a491cb3a in QEventDispatcherX11::processEvents (this=0x1bfbad0, flags=...) at kernel/qeventdispatcher_x11.cpp:132
#15 0x00007fc0a54efc82 in QEventLoop::processEvents (this=<optimized out>, flags=...) at kernel/qeventloop.cpp:149
#16 0x00007fc0a54efed7 in QEventLoop::exec (this=0x7fff6f4ebff0, flags=...) at kernel/qeventloop.cpp:204
#17 0x00007fc0a54f4f67 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1148
#18 0x00007fc0aa053c36 in kdemain (argc=<optimized out>, argv=<optimized out>) at ../../kwin/main.cpp:541
#19 0x00007fc0a9c5576d in __libc_start_main (main=0x400630 <main(int, char**)>, argc=1, ubp_av=0x7fff6f4ec7d8, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7fff6f4ec7c8) at libc-start.c:226
#20 0x0000000000400661 in _start ()

Possible duplicates by query: bug 308535, bug 299728, bug 298370, bug 298304, bug 293648.

Reported using DrKonqi