Application: kwin (4.6.3 (4.6.3))
KDE Platform Version: 4.6.3 (4.6.3)
Qt Version: 4.7.3
Operating System: Linux 3.0-3-generic x86_64
Distribution: Ubuntu oneiric (development branch)

-- Information about the crash:
Playing with KUbuntu Oneiric, I had a broken KDE for a while. After recent updates I stopped X, deleted ~/.kde, started kdm and logged in with a new clean kde session.
The crash notifier popped up, but KDE seemed to have recovered

-- Backtrace:
Application: KWin (kwin), signal: Segmentation fault
[KCrash Handler]
#6  __memcpy_ssse3 () at ../sysdeps/x86_64/multiarch/memcpy-ssse3.S:91
#7  0x00007f142754ab5e in ?? () from /usr/lib/x86_64-linux-gnu/mesa/libGL.so.1
#8  0x00007f14114f068f in KWin::ARBBlurShader::init (this=0xfb9c90) at ../../../kwin/effects/blur/blurshader.cpp:473
#9  0x00007f14114ed9fb in KWin::BlurEffect::reconfigure (this=0xf3eca0, flags=<value optimized out>) at ../../../kwin/effects/blur/blur.cpp:76
#10 0x00007f14114edb87 in KWin::BlurEffect::BlurEffect (this=0xf3eca0) at ../../../kwin/effects/blur/blur.cpp:48
#11 0x00007f14114edc36 in KWin::effect_create_kwin4_effect_blur () at ../../../kwin/effects/blur/blur.cpp:29
#12 0x00007f142a018ca1 in KWin::EffectsHandlerImpl::loadEffect (this=0xf33760, name=...) at ../../kwin/effects.cpp:1128
#13 0x00007f142a019d69 in KWin::EffectsHandlerImpl::reconfigure (this=0xf33760) at ../../kwin/effects.cpp:143
#14 0x00007f1429ff396a in KWin::Workspace::setupCompositing (this=0xf62f30) at ../../kwin/composite.cpp:216
#15 0x00007f1429f77ce3 in KWin::Workspace::Workspace (this=0xf62f30, restore=false) at ../../kwin/workspace.cpp:222
#16 0x00007f1429f8eeac in KWin::Application::Application (this=<value optimized out>) at ../../kwin/main.cpp:330
#17 0x00007f1429f909fc in kdemain (argc=<value optimized out>, argv=<value optimized out>) at ../../kwin/main.cpp:516
#18 0x00007f1429bafe1f in __libc_start_main (main=0x400640 <main(int, char**)>, argc=3, ubp_av=0x7fff7fbc7e78, init=<value optimized out>, fini=<value optimized out>, rtld_fini=<value optimized out>, stack_end=0x7fff7fbc7e68) at libc-start.c:226
#19 0x0000000000400671 in _start ()

Reported using DrKonqi