Application: kwin (4.4.1 (KDE 4.4.1))
KDE Platform Version: 4.4.1 (KDE 4.4.1)
Qt Version: 4.6.2
Operating System: Linux 2.6.33-ARCH x86_64
Distribution (Platform): Archlinux Packages

-- Information about the crash:
If i try to change plasma theme -> kwin and plasma crash
100% reproducible for me.

this is trace for plasma:
Application: Рабочее пространство Plasma (kdeinit4), signal: Bus error
[KCrash Handler]
#5  0x00007f49f6b496c0 in KPixmapCache::Private::mmapFile(QString const&, KPixmapCache::Private::MmapInfo*, int) () from /usr/lib/libkdeui.so.5
#6  0x00007f49f6b4af64 in KPixmapCache::Private::mmapFiles() () from /usr/lib/libkdeui.so.5
#7  0x00007f49f6b4ad83 in KPixmapCache::Private::init() () from /usr/lib/libkdeui.so.5
#8  0x00007f49f6b4c7ed in KPixmapCache::discard() () from /usr/lib/libkdeui.so.5
#9  0x00007f49f6b4ced8 in KPixmapCache::deleteCache(QString const&) () from /usr/lib/libkdeui.so.5
#10 0x00007f49edd42fad in Plasma::ThemePrivate::discardCache() () from /usr/lib/libplasma.so.3
#11 0x00007f49edd4664b in Plasma::ThemePrivate::setThemeName(QString const&, bool) () from /usr/lib/libplasma.so.3
#12 0x00007f49edd47ebb in Plasma::Theme::settingsChanged() () from /usr/lib/libplasma.so.3
#13 0x00007f49edd48bf8 in Plasma::ThemePrivate::settingsFileChanged(QString const&) () from /usr/lib/libplasma.so.3
#14 0x00007f49edd48f86 in Plasma::Theme::qt_metacall(QMetaObject::Call, int, void**) () from /usr/lib/libplasma.so.3
#15 0x00007f49f65ab4df in QMetaObject::activate(QObject*, QMetaObject const*, int, void**) () from /usr/lib/libQtCore.so.4
#16 0x00007f49f700b145 in KDirWatch::created(QString const&) () from /usr/lib/libkio.so.5
#17 0x00007f49f700b920 in KDirWatch::setCreated(QString const&) () from /usr/lib/libkio.so.5
#18 0x00007f49f700ba71 in KDirWatch::qt_metacall(QMetaObject::Call, int, void**) () from /usr/lib/libkio.so.5
#19 0x00007f49f65a8419 in QObject::event(QEvent*) () from /usr/lib/libQtCore.so.4
#20 0x00007f49f57405ec in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#21 0x00007f49f5746bdb in QApplication::notify(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#22 0x00007f49f6acad36 in KApplication::notify(QObject*, QEvent*) () from /usr/lib/libkdeui.so.5
#23 0x00007f49f659879c in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib/libQtCore.so.4
#24 0x00007f49f659af17 in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) () from /usr/lib/libQtCore.so.4
#25 0x00007f49f65c20d3 in ?? () from /usr/lib/libQtCore.so.4
#26 0x00007f49f1a032be in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#27 0x00007f49f1a06c78 in g_main_context_iterate () from /usr/lib/libglib-2.0.so.0
#28 0x00007f49f1a06da0 in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#29 0x00007f49f65c1c13 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#30 0x00007f49f57eed6e in ?? () from /usr/lib/libQtGui.so.4
#31 0x00007f49f65970c2 in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#32 0x00007f49f659749c in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#33 0x00007f49f659b1db in QCoreApplication::exec() () from /usr/lib/libQtCore.so.4
#34 0x00007f49e9f4cd22 in kdemain () from /usr/lib/libkdeinit4_plasma-desktop.so
#35 0x0000000000406b7e in _start ()


 -- Backtrace:
Application: KWin (kwin), signal: Bus error
[KCrash Handler]
#5  0x00007f1d178cd02f in KPixmapCache::Private::invalidateMmapFiles() () from /usr/lib/libkdeui.so.5
#6  0x00007f1d178cbc34 in KPixmapCache::recreateCacheFiles() () from /usr/lib/libkdeui.so.5
#7  0x00007f1d178cc4d6 in KPixmapCache::Private::loadIndexHeader() () from /usr/lib/libkdeui.so.5
#8  0x00007f1d178ccd70 in KPixmapCache::Private::init() () from /usr/lib/libkdeui.so.5
#9  0x00007f1d178ce7ed in KPixmapCache::discard() () from /usr/lib/libkdeui.so.5
#10 0x00007f1d178ceed8 in KPixmapCache::deleteCache(QString const&) () from /usr/lib/libkdeui.so.5
#11 0x00007f1d172fbfad in Plasma::ThemePrivate::discardCache() () from /usr/lib/libplasma.so.3
#12 0x00007f1d172ff64b in Plasma::ThemePrivate::setThemeName(QString const&, bool) () from /usr/lib/libplasma.so.3
#13 0x00007f1d17300ebb in Plasma::Theme::settingsChanged() () from /usr/lib/libplasma.so.3
#14 0x00007f1d17301bf8 in Plasma::ThemePrivate::settingsFileChanged(QString const&) () from /usr/lib/libplasma.so.3
#15 0x00007f1d17301f86 in Plasma::Theme::qt_metacall(QMetaObject::Call, int, void**) () from /usr/lib/libplasma.so.3
#16 0x00007f1d13bf94df in QMetaObject::activate(QObject*, QMetaObject const*, int, void**) () from /usr/lib/libQtCore.so.4
#17 0x00007f1d128cf145 in KDirWatch::created(QString const&) () from /usr/lib/libkio.so.5
#18 0x00007f1d128cf920 in KDirWatch::setCreated(QString const&) () from /usr/lib/libkio.so.5
#19 0x00007f1d128cfa71 in KDirWatch::qt_metacall(QMetaObject::Call, int, void**) () from /usr/lib/libkio.so.5
#20 0x00007f1d13bf6419 in QObject::event(QEvent*) () from /usr/lib/libQtCore.so.4
#21 0x00007f1d1431b5ec in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#22 0x00007f1d14321bdb in QApplication::notify(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#23 0x00007f1d1784cd36 in KApplication::notify(QObject*, QEvent*) () from /usr/lib/libkdeui.so.5
#24 0x00007f1d13be679c in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib/libQtCore.so.4
#25 0x00007f1d13be8f17 in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) () from /usr/lib/libQtCore.so.4
#26 0x00007f1d13c100d3 in ?? () from /usr/lib/libQtCore.so.4
#27 0x00007f1d0e4832be in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#28 0x00007f1d0e486c78 in g_main_context_iterate () from /usr/lib/libglib-2.0.so.0
#29 0x00007f1d0e486da0 in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#30 0x00007f1d13c0fc13 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#31 0x00007f1d143c9d6e in ?? () from /usr/lib/libQtGui.so.4
#32 0x00007f1d13be50c2 in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#33 0x00007f1d13be549c in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#34 0x00007f1d13be91db in QCoreApplication::exec() () from /usr/lib/libQtCore.so.4
#35 0x00007f1d18004eae in kdemain () from /usr/lib/libkdeinit4_kwin.so
#36 0x00007f1d17c80b6d in __libc_start_main () from /lib/libc.so.6
#37 0x00000000004005c9 in _start ()

Reported using DrKonqi