I reported this bug to bugs.kde.org and they said that the crash is because of the video driver so i should send it upstream. I have Mesa 7.8.2 and Xorg 1.8.0- the default coming with openSUSE 11.3. My video card is ATI Radeon HD3450.

Here is a copy of the bug i sent to Bugs.kde

Application: kwin (4.5.00 (KDE 4.5.0))
KDE Platform Version: 4.5.00 (KDE 4.5.0)
Qt Version: 4.6.3
Operating System: Linux 2.6.34-12-default i686
Distribution: "openSUSE 11.3 (i586)"

-- Information about the crash:
- What I was doing when the application crashed:
Kwin crashes every time i change the window decoration. It recovers almost
instantly with the new decoration that i selected. Sometimes after recovery the
desktop effects are stopped and i have to turn them on. The crash also occurrs when i setup transperant windows with exactly the same crash.

The crash can be reproduced every time.
-- Backtrace:
Application: KWin (kwin), signal: Segmentation fault
[KCrash Handler]
#7  0xb6b2727b in dri2DrawableGetMSC (psc=0x83f6ff8, pdraw=0x0, ust=0xbfb51a28,
msc=0xbfb51a20, sbc=0xbfb51a18) at dri2_glx.c:226
#8  0xb6b00107 in __glXGetVideoSyncSGI (count=0xbfb51a6c) at glxcmds.c:2317
#9  0xb761d5c4 in KWin::SceneOpenGL::waitSync (this=0x89a96c0) at
/usr/src/debug/kdebase-workspace-4.5.0/kwin/scene_opengl.cpp:781
#10 0xb7633874 in KWin::SceneOpenGL::flushBuffer (this=0x89a96c0, mask=32,
damage=...) at /usr/src/debug/kdebase-workspace-4.5.0/kwin/scene_opengl.cpp:830
#11 0xb768588a in KWin::SceneOpenGL::paint (this=0x89a96c0, damage=...,
toplevels=...) at
/usr/src/debug/kdebase-workspace-4.5.0/kwin/scene_opengl.cpp:761
#12 0xb7662794 in KWin::Workspace::performCompositing (this=0x81a2a48) at
/usr/src/debug/kdebase-workspace-4.5.0/kwin/composite.cpp:454
#13 0xb7695a5b in KWin::Workspace::qt_metacall (this=0x81a2a48,
_c=QMetaObject::InvokeMetaMethod, _id=<value optimized out>, _a=0xbfb51d5c)
    at /usr/src/debug/kdebase-workspace-4.5.0/build/kwin/workspace.moc:583
#14 0xb669befd in QMetaObject::metacall (object=0x81a2a48,
cl=QMetaObject::InvokeMetaMethod, idx=190, argv=0xbfb51d5c) at
kernel/qmetaobject.cpp:237
#15 0xb66aafe8 in QMetaObject::activate (sender=0x81a2cf8, m=0xb67b25a4,
local_signal_index=0, argv=0x0) at kernel/qobject.cpp:3295
#16 0xb66f7a35 in QTimer::timeout (this=0x81a2cf8) at
.moc/release-shared/moc_qtimer.cpp:134
#17 0xb66b08e6 in QTimer::timerEvent (this=0x81a2cf8, e=0xbfb522b0) at
kernel/qtimer.cpp:271
#18 0xb66a8774 in QObject::event (this=0x81a2cf8, e=0xbfb522b0) at
kernel/qobject.cpp:1212
#19 0xb5bcfc64 in QApplicationPrivate::notify_helper (this=0x8070350,
receiver=0x81a2cf8, e=0xbfb522b0) at kernel/qapplication.cpp:4302
#20 0xb5bd7bf7 in QApplication::notify (this=0xbfb525e4, receiver=0x81a2cf8,
e=0xbfb522b0) at kernel/qapplication.cpp:3706
#21 0xb719b2c1 in KApplication::notify (this=0xbfb525e4, receiver=0x81a2cf8,
event=0xbfb522b0) at
/usr/src/debug/kdelibs-4.5.0/kdeui/kernel/kapplication.cpp:310
#22 0xb75f7c4f in KWin::Application::notify (this=0xbfb525e4, o=0x81a2cf8,
e=0xbfb522b0) at /usr/src/debug/kdebase-workspace-4.5.0/kwin/main.cpp:372
#23 0xb6695e0e in QCoreApplication::notifyInternal (this=0xbfb525e4,
receiver=0x81a2cf8, event=0xbfb522b0) at kernel/qcoreapplication.cpp:726
#24 0xb66c470e in sendEvent (this=0x8070b28) at kernel/qcoreapplication.h:215
#25 QTimerInfoList::activateTimers (this=0x8070b28) at
kernel/qeventdispatcher_unix.cpp:618
#26 0xb66c4ffd in QEventDispatcherUNIX::processEvents (this=0x806f280,
flags=...) at kernel/qeventdispatcher_unix.cpp:939
#27 0xb5c80f5a in QEventDispatcherX11::processEvents (this=0x806f280,
flags=...) at kernel/qeventdispatcher_x11.cpp:152
#28 0xb669511d in QEventLoop::processEvents (this=0xbfb52534, flags=...) at
kernel/qeventloop.cpp:149
#29 0xb6695319 in QEventLoop::exec (this=0xbfb52534, flags=...) at
kernel/qeventloop.cpp:201
#30 0xb6699c70 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1003
#31 0xb5bcd164 in QApplication::exec () at kernel/qapplication.cpp:3581
#32 0xb7693fab in kdemain (argc=3, argv=0xbfb52834) at
/usr/src/debug/kdebase-workspace-4.5.0/kwin/main.cpp:531
#33 0x0804860b in main (argc=3, argv=0xbfb52834) at
/usr/src/debug/kdebase-workspace-4.5.0/build/kwin/kwin_dummy.cpp:3