This also happens to me on FC4 and Gnome. I can go to Desktop and click on Log Out and the system freezes. The only way I currently know of to get out of this is to do CTL-ALT-F1 and issue shutdown -r "now" as root under bash. Of course one often loses data by this method and it is slow and clumsy. I wish I knew of a better way out. CroombeFP