My FC4 system hangs in that interval after logging off (or shutting down) from KDE but before the Fedora login screen comes on. I can move a cursor around with the mouse on the blank screen but get no response from clicking it, or from hitting anything on the keyboard. So, the reset button -- after which a command-line login appears and there's a normal-looking shutdown. The re-boot and login look normal.
Is there some other way of logging off (or shutting) down that might give me a clue as to what's happening?
I suspect a USB-related hardware issue but don't know for sure.
Jerry