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After last upgrade to KDE 4.4 i cant reboot or shut down , i have to shutdown through init0
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Had this too and could solve it somehow, but can't tell you exactly how, I just reinstalled kde a few times and started with a clean kde config. I can only give you the hint that system sounds (login/logout sound especially) didn't work when KDE wouldn't logout/shutdown/reboot, so you might look in the phonon direction. Also make sure you don't still have old or wrong kde packages (I somehow pulled in kdelibs-experimental, although I had enabled only core, extra and community repositories).
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I had to add KDM for my machine to shutdown/reboot.
http://wiki.archlinux.org/index.php/KDM
http://wiki.archlinux.org/index.php/XDM#GRUB
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Same problem for me after upgrade to KDE 4.4.
I have custom sounds notifications for login/shutdown and changing the sound engine from Phonon-Gstreamer to Phonon-Xine seems to have solved the issue.
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I am having this same problem. It worked for a while after the KDE 4.4 upgrade which I did the next day after it was released so the problem has to be a recent update. I appreciate the fixes that are offered as it will help me.
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