Application: kwin (4.8.2 (4.8.2))
KDE Platform Version: 4.8.2 (4.8.2)
Qt Version: 4.8.1
Operating System: Linux 3.0.0-17-generic-pae i686
Distribution: Ubuntu 11.10

-- Information about the crash:
- What I was doing when the application crashed:

- Unusual behavior I noticed:

When opening an external link from Thunderbird or Akregator or many other application just everithing crashes and the session is ended. New login screen appears and plasma desktop restarts a new blank session.
It happened once also on clicking the "show desktop" widget I have in the task bar.

The crash can be reproduced some of the time.

-- Backtrace:
Application: KWin (kwin), signal: Aborted
[KCrash Handler]
#7  0xb773d424 in __kernel_vsyscall ()
#8  0xb7481c8f in raise () from /lib/i386-linux-gnu/libc.so.6
#9  0xb74852b5 in abort () from /lib/i386-linux-gnu/libc.so.6
#10 0xb5e766a6 in qt_message_output (msgType=QtFatalMsg, buf=0x9698ef8 "kwin(29750)/kdeui (kdelibs): Session bus not found \nTo circumvent this problem try the following command (with Linux and bash) \nexport $(dbus-launch) ") at global/qglobal.cpp:2276
#11 0xb70fbd40 in ~QDebug (this=0xbf916188, __in_chrg=<optimized out>) at /usr/include/qt4/QtCore/qdebug.h:85
#12 QDebug::~QDebug (this=0xbf916188, __in_chrg=<optimized out>) at /usr/include/qt4/QtCore/qdebug.h:81
#13 0xb7202996 in KApplicationPrivate::init (this=0x9623c68, GUIenabled=true) at ../../kdeui/kernel/kapplication.cpp:516
#14 0xb7203b24 in KApplication::KApplication (this=0xbf9168d8, GUIenabled=true) at ../../kdeui/kernel/kapplication.cpp:352
#15 0xb763c6e5 in ?? () from /usr/lib/kde4/libkdeinit/libkdeinit4_kwin.so
#16 0xb763ee2e in kdemain () from /usr/lib/kde4/libkdeinit/libkdeinit4_kwin.so
#17 0x0804850b in ?? ()
#18 0xb746d113 in __libc_start_main () from /lib/i386-linux-gnu/libc.so.6
#19 0x08048531 in _start ()

Possible duplicates by query: bug 290088, bug 286944, bug 283935, bug 282182, bug 279962.

Reported using DrKonqi