Application: kwin (4.7.2 (4.7.2))
KDE Platform Version: 4.7.2 (4.7.2)
Qt Version: 4.7.4
Operating System: Linux 3.0.0-13-generic x86_64
Distribution: Ubuntu 11.10

-- Information about the crash:
And it is not even hard.

You just have to run BleachBit (bleachbit-cli on another session WILL work) with all options (because I do not know which option is the one that kills everything).
Every program you start after the cleanup and every program running at the moment will CRASH. This also works if you are another, evil, user running bleachbit-cli on ssh to kill the KDE-screenlock of another user using the KDE desktop environment.

How to reconstruct the bug:
1. Lock the screen
2. Press Ctrl+Alt+F1 (or whatever).
3. login as any user
4. run bleachbit-cli with all options
5. return to Ctrl+Alt+F7 and move your mouse
6. The screen lock and every program protecting the session CRASHES!

I could not believe that it works, but it does. And it also works on another computers I use to test this.
You do not have to  run bleachbit as root. I am sure that it will also work if you login per ssh. Try it! O.O

This is the first program which crashed. To report the other ones, I need the debug symbols - and apt-get keeps crashing. xD

-- END OF (hopefully) LAST PART --
Again, debug symbols are missing because the policy-kit crashed.

I hope I could help you to find out what the problem is; if not, feel free to ask questions about the crash; I will answer them. If you REALLY need it, I could also make a video of what is happening and how to reconstruct the bug. :-)

The crash can be reproduced every time.

-- Backtrace:
Application: KWin (kwin), signal: Bus error
[Current thread is 1 (Thread 0x7f0f6d78b7c0 (LWP 1864))]

Thread 3 (Thread 0x7f0f50d0d700 (LWP 1873)):
#0  0x00007f0f6cfc2913 in select () at ../sysdeps/unix/syscall-template.S:82
#1  0x00007f0f69314bc6 in qt_safe_select (nfds=22, fdread=0x19f6090, fdwrite=0x19f6328, fdexcept=0x19f65c0, orig_timeout=<optimized out>) at kernel/qcore_unix.cpp:82
#2  0x00007f0f6931a330 in QEventDispatcherUNIXPrivate::doSelect (this=0x19f5ed0, flags=..., timeout=0x0) at kernel/qeventdispatcher_unix.cpp:219
#3  0x00007f0f6931a833 in QEventDispatcherUNIX::processEvents (this=0x19f2b70, flags=...) at kernel/qeventdispatcher_unix.cpp:918
#4  0x00007f0f692ebcf2 in QEventLoop::processEvents (this=<optimized out>, flags=...) at kernel/qeventloop.cpp:149
#5  0x00007f0f692ebef7 in QEventLoop::exec (this=0x7f0f50d0ccd0, flags=...) at kernel/qeventloop.cpp:201
#6  0x00007f0f6920327f in QThread::exec (this=<optimized out>) at thread/qthread.cpp:498
#7  0x00007f0f692cecbf in QInotifyFileSystemWatcherEngine::run (this=0x19f4c90) at io/qfilesystemwatcher_inotify.cpp:248
#8  0x00007f0f69205d05 in QThreadPrivate::start (arg=0x19f4c90) at thread/qthread_unix.cpp:331
#9  0x00007f0f6a82b56c in ?? () from /usr/lib/nvidia-current/libGL.so.1
#10 0x00007f0f6346cefc in start_thread (arg=0x7f0f50d0d700) at pthread_create.c:304
#11 0x00007f0f6cfc989d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#12 0x0000000000000000 in ?? ()

Thread 2 (Thread 0x7f0f4afbf700 (LWP 1874)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:162
#1  0x00007f0f6be23fe2 in ?? () from /usr/lib/x86_64-linux-gnu/libQtScript.so.4
#2  0x00007f0f6be24019 in ?? () from /usr/lib/x86_64-linux-gnu/libQtScript.so.4
#3  0x00007f0f6a82b56c in ?? () from /usr/lib/nvidia-current/libGL.so.1
#4  0x00007f0f6346cefc in start_thread (arg=0x7f0f4afbf700) at pthread_create.c:304
#5  0x00007f0f6cfc989d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#6  0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7f0f6d78b7c0 (LWP 1864)):
[KCrash Handler]
#6  0x00007f0f69ad36f7 in lock (this=0x11c6c20) at ../../kdecore/util/kshareddatacache.cpp:1123
#7  KSharedDataCache::Private::CacheLocker::cautiousLock (this=0x7fffc1bb4230) at ../../kdecore/util/kshareddatacache.cpp:1146
#8  0x00007f0f69acf959 in CacheLocker (_d=<optimized out>, this=0x7fffc1bb4230) at ../../kdecore/util/kshareddatacache.cpp:1170
#9  KSharedDataCache::find (this=0x11ea0a0, key=..., destination=0x7fffc1bb4300) at ../../kdecore/util/kshareddatacache.cpp:1492
#10 0x00007f0f6ca65dd9 in KIconLoaderPrivate::findCachedPixmapWithPath (this=0x11d4c60, key=..., data=..., path=...) at ../../kdeui/icons/kiconloader.cpp:860
#11 0x00007f0f6ca660f1 in KIconLoader::loadIcon (this=0x11b24a0, _name=<optimized out>, group=KIconLoader::Small, size=32, state=0, overlays=..., path_store=0x0, canReturnNull=true) at ../../kdeui/icons/kiconloader.cpp:1222
#12 0x00007f0f6cbec53c in KWindowSystem::icon (win=98566740, width=32, height=32, scale=true, flags=12) at ../../kdeui/windowmanagement/kwindowsystem_x11.cpp:688
#13 0x00007f0f6d2d07a2 in ?? () from /usr/lib/kde4/libkdeinit/libkdeinit4_kwin.so
#14 0x00007f0f6d3143f8 in ?? () from /usr/lib/kde4/libkdeinit/libkdeinit4_kwin.so
#15 0x00007f0f6d2c2a62 in ?? () from /usr/lib/kde4/libkdeinit/libkdeinit4_kwin.so
#16 0x00007f0f6d304f6a in ?? () from /usr/lib/kde4/libkdeinit/libkdeinit4_kwin.so
#17 0x00007f0f6d2e0558 in ?? () from /usr/lib/kde4/libkdeinit/libkdeinit4_kwin.so
#18 0x00007f0f6870ca55 in qt_x11EventFilter (ev=0x7fffc1bb5590) at kernel/qapplication_x11.cpp:440
#19 qt_x11EventFilter (ev=0x7fffc1bb5590) at kernel/qapplication_x11.cpp:428
#20 0x00007f0f6871bc90 in QApplication::x11ProcessEvent (this=0x7fffc1bb58a0, event=0x7fffc1bb5590) at kernel/qapplication_x11.cpp:3402
#21 0x00007f0f68745e2a in QEventDispatcherX11::processEvents (this=0x1081f40, flags=...) at kernel/qeventdispatcher_x11.cpp:132
#22 0x00007f0f692ebcf2 in QEventLoop::processEvents (this=<optimized out>, flags=...) at kernel/qeventloop.cpp:149
#23 0x00007f0f692ebef7 in QEventLoop::exec (this=0x7fffc1bb57e0, flags=...) at kernel/qeventloop.cpp:201
#24 0x00007f0f692f0789 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1064
#25 0x00007f0f6d2e2ca6 in kdemain () from /usr/lib/kde4/libkdeinit/libkdeinit4_kwin.so
#26 0x00007f0f6cf0930d in __libc_start_main (main=0x400630, argc=3, ubp_av=0x7fffc1bb5f08, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7fffc1bb5ef8) at libc-start.c:226
#27 0x0000000000400661 in _start ()

Possible duplicates by query: bug 284821, bug 284819, bug 284770, bug 284041.

Reported using DrKonqi