I have qt-4.5.0_rc1 installed and kde 4.2. It seems like the ksmserver creates zombie processes. In principle I would not care about zombie processes but as soon as there are any I cannot log out anymore. Removing the ksmserverrc and everything from Autostart allows me to login/logout one time. The command "ps -U <username> --forest" gives the following output: 6032 ? 00:00:00 kdeinit4 6033 ? 00:00:00 \_ klauncher 6044 ? 00:00:00 \_ ksmserver 6046 ? 00:00:01 | \_ kwin 6065 ? 00:00:00 | \_ nepomukserver <defunct> 6070 ? 00:00:00 | \_ kmix <defunct> 6072 ? 00:00:00 | \_ amarok <defunct> 6074 ? 00:00:00 | \_ kopete <defunct> 6076 ? 00:00:02 | \_ skype 6095 ? 00:00:00 | \_ kget <defunct> 6098 ? 00:00:00 | \_ kwalletmanager <defunct> 6100 ? 00:00:00 | \_ konsole <defunct> 6107 ? 00:00:00 | \_ easystroke <defunct> 6109 ? 00:00:00 | \_ nvidia-settings <defunct> Reproducible: Always Steps to Reproduce: I tried reinstalled qt, ksmserver and kdelibs but the problem is always the same.
I could fix the problem myself by downgrading to a previous nvidia-driver. I don't know how this correlates but it works again.
*** This bug has been marked as a duplicate of bug 260441 ***
