I have the same issue - logout or shutdown does nothing, the confirmation dialogue does not appear. Sometimes (typically the 1st time trying to log out) the screen dims to B/W from colour - as if logging out. then nothing happens and instead of displaying the confirmation dialogue the KDE desktop becomes coloured again.
I have tried the fix posted by hobz, but with no success - behaviour of KDE is same.
Supprosingly, the suspend to RAM or to disk works well...
But to log out, I have to kill X or switch to runlevel 3 and then back to 5 :-(
Anybody else with similar experience? Any ideas how to fix this?
No upgrade in my case, but a fresh FC14 64bit installation.
If I remember well, the first few months in the beginning of using this FC14 installation this problem did not occur. (using FC14 since approx. 12/2010)
I have another two FC 14 installations, one 32bit (fresh) one 64bit (upgrade FC12->FC13->FC14), where I have no such a problem.