Version: (using Devel) Installed from: Compiled sources When the confirmation for logging out of KDE is disabled (unchecked) under "System settings" - "Advanced" - "Session manager" it will shut down the computer instead of actually logging out. Logging out of KDE works fine when confirmation is enabled (checked). I have this bug on Fedora 10 with kde-redhat repo's enabled, which are currently running KDE 4.2 beta 2.
Let's call them Fedora RPMs, they're built from the Rawhide SRPMs. :-)
*** This bug has been marked as a duplicate of bug 164818 ***