Session logout from KDE in FC8 for x86_64

[ggallup at unlserve.unl.edu]

Greetings,
    I find that, intermittently,  I cannot end a KDE session with the  
logout button on the lower left.  All other items on the popup seem to  
work.  Killing X on tty7 from another tty, of course, works.  Has  
anyone else seen this?
GAG