This weekend I did a fresh 2008.1 GNOME only installation, upgraded it
to cooker, and installed task-kde4. Now right after I login, I get a
knotify4 crash error popping up every second making the whole desktop
unusable.

I tried installing some -debug packages
(kdebase4-runtime-debug-4.0.81-1mdv2009.0,
kdelibs4-debug-4.0.81-1mdv2009.0 and qt4-debug-4.4.0-4mdv2009.0), but I
still only got this incomplete backtrace:

Application: KNotify (knotify4), signal SIGABRT
(no debugging symbols found)
Using host libthread_db library "/lib64/libthread_db.so.1".
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
[Thread debugging using libthread_db enabled]
[New Thread 140364738717440 (LWP 5111)]
[New Thread 1105254736 (LWP 5199)]
[New Thread 1096862032 (LWP 5189)]
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
[KCrash handler]
#5 0x00007fa931290945 in raise () from /lib64/libc.so.6
#6 0x00007fa931292173 in abort () from /lib64/libc.so.6
#7 0x00007fa935a37405 in qt_message_output ()
from /usr/lib64/libQtCore.so.4
#8 0x00007fa935a3752d in qFatal () from /usr/lib64/libQtCore.so.4
#9 0x00007fa92c5b1b7a in QObject::disconnectNotify ()
 from /usr/lib64/kde4/phonon_xine.so
#10 0x00007fa92c5b7479 in QObject::disconnectNotify ()
 from /usr/lib64/kde4/phonon_xine.so
#11 0x00007fa92c5b9d61 in QObject::disconnectNotify ()
 from /usr/lib64/kde4/phonon_xine.so
#12 0x00007fa933d231cd in QApplicationPrivate::notify_helper ()
 from /usr/lib64/libQtGui.so.4
#13 0x00007fa933d2a4fe in QApplication::notify ()
 from /usr/lib64/libQtGui.so.4
#14 0x00007fa93280f23e in KApplication::notify ()
 from /usr/lib64/libkdeui.so.5
#15 0x00007fa935b1ee0c in QCoreApplication::notifyInternal ()
 from /usr/lib64/libQtCore.so.4
#16 0x00007fa935b22684 in QCoreApplicationPrivate::sendPostedEvents ()
 from /usr/lib64/libQtCore.so.4
#17 0x00007fa935b48300 in QEventDispatcherUNIX::processEvents ()
 from /usr/lib64/libQtCore.so.4
#18 0x00007fa935b1da32 in QEventLoop::processEvents ()
 from /usr/lib64/libQtCore.so.4
#19 0x00007fa935b1dbc5 in QEventLoop::exec ()
from /usr/lib64/libQtCore.so.4
#20 0x00007fa935a3c6dc in QThread::exec ()
from /usr/lib64/libQtCore.so.4
#21 0x00007fa92c5aef9f in QObject::disconnectNotify ()
 from /usr/lib64/kde4/phonon_xine.so
#22 0x00007fa935a3f9e4 in QObject::disconnectNotify ()
 from /usr/lib64/libQtCore.so.4
#23 0x00007fa9357c72a3 in start_thread () from /lib64/libpthread.so.0
#24 0x00007fa93133be9d in clone () from /lib64/libc.so.6

Thread 1 (Thread 140364738717440 (LWP 5111)):
#0 0x00007fa9357caf59 in pthread_cond_wait@@(protected) ()
 from /lib64/libpthread.so.0
#1 0x00007fa935a3ed2b in QObject::disconnectNotify ()
 from /usr/lib64/libQtCore.so.4
#2 0x00007fa935a3a1ab in QMutex::lock () from /usr/lib64/libQtCore.so.4
#3 0x00007fa92c5b69f7 in QObject::disconnectNotify ()
 from /usr/lib64/kde4/phonon_xine.so
#4 0x00007fa92c5c4a5c in QObject::disconnectNotify ()
 from /usr/lib64/kde4/phonon_xine.so
#5 0x00007fa9323e567b in Phonon::MediaNodePrivate::deleteBackendObject
()
 from /usr/lib64/libphonon.so.4
#6 0x00007fa9323f84c2 in Phonon::FactoryPrivate::~FactoryPrivate$delete
()
 from /usr/lib64/libphonon.so.4
#7 0x00007fa9323f74b4 in QObject::disconnectNotify ()
 from /usr/lib64/libphonon.so.4
#8 0x00007fa9323dcacd in
Phonon::CleanUpGlobalStatic::~CleanUpGlobalStatic ()
 from /usr/lib64/libphonon.so.4
#9 0x00007fa93129382d in exit () from /lib64/libc.so.6
#10 0x00007fa933d7ab18 in QObject::disconnectNotify ()
 from /usr/lib64/libQtGui.so.4
#11 0x00007fa93280ddd0 in KApplication::xioErrhandler ()
 from /usr/lib64/libkdeui.so.5
#12 0x00007fa9350abe83 in _XIOError () from /usr/lib64/libX11.so.6
#13 0x00007fa9350b5471 in QObject::disconnectNotify ()
 from /usr/lib64/libX11.so.6
#14 0x00007fa9350b555a in _XEventsQueued () from /usr/lib64/libX11.so.6
#15 0x00007fa93509420e in XEventsQueued () from /usr/lib64/libX11.so.6
#16 0x00007fa933daba77 in QObject::disconnectNotify ()
 from /usr/lib64/libQtGui.so.4
#17 0x00007fa935b1da32 in QEventLoop::processEvents ()
 from /usr/lib64/libQtCore.so.4
#18 0x00007fa935b1dbc5 in QEventLoop::exec ()
from /usr/lib64/libQtCore.so.4
#19 0x00007fa935b22937 in QCoreApplication::exec ()
 from /usr/lib64/libQtCore.so.4
#20 0x000000000040653b in _start ()
#0 0x00007fa9357caf59 in pthread_cond_wait@@(protected) ()
 from /lib64/libpthread.so.0

This could be similar to one of these:
http://bugs.kde.org/show_bug.cgi?id=149290
http://bugs.kde.org/show_bug.cgi?id=161572

Does anybody know why I don't get a useful backtrace?

Related to KDE 4, I was also wondering why gwenview and marble are not
included in task-kde4: reading all KDE 4 blogs, I had the impression
that these two are two of the "killer applications" in KDE 4.