New install of XP SP1 Home. Users can logon, but cannot
logoff. Logoff screen is presented (options Logoff and
Switch User) but user is returned immediately to the
Desktop.
Can shut down by switching users to Login Screen, then
selecting Shutdown.
Have loaded latest patches - is a OS reload required?
The difference in the two shutdown methods is markedly different. When
shutting down from within the user accounts, background programs and
processes have to be ended before Windows shuts down. When you log users
off first, their startup programs are unloaded. Windows then shuts down
normally.
By default Windows will perform an automatic restart when there is a
serious error. It would appear that there is a background program, driver or
process that is common to all of your user profiles and that it is causing this
automatic restart.
Event Viewer may have more information about this. Start> Run> eventvwr.msc
will start that tool. Also, turning off automatic restart in System Properties>
Advanced> Startup and Recovery may cause an error message to appear on the
screen that Event Viewer is not capturing. Instead of a complete restart, you
may end up looking at a blue screen and have to manually restart the machine
but that blue screen may give you more info.
Also, see MVP Jim Eshelman's shutdown troubleshooting site. It's a great
guide for working out a problem of this type:
http://www.aumha.org/win5/a/shtdwnxp.htm
