I've been using Windows Vista Ultimate for almost three months now, and all
of a sudden tonight I couldn't log on to my laptop. Every time I tried I
received the message "The User Profile Service failed the logon. The User
Profile failed to load." I had successfully logged on to it only five hours
earlier, so I did not understand what could be going on.
Fortunately after Googling the error message (I originally used Microsoft
Live Searct, but did not get any results), I found someone who had a similar
error and had found that his profile had entered a backup state. I logged on
with my domain administrator account (it's good to be the king sometimes) and
examined the keys under HKLM\Software\Microsoft\Windows NT\Current
User\ProfileList\ and was able to find the key for my user id SID. Sure
enough, the key had a ".bak" appended to it and there was an identical one
that was set to a temp directory. I renamed the other key, removed the
".bak" from mine, and changed the State property under my key to 0. This
allowed me to log in.
Does anyone know what might have caused this issue? If this is a bug, its a
pretty severe one, as I can just imagine a help desk trying to resolve this
over the phone with their laptop users who all of a sudden can't log in.
Solution can be found here :- http://www.vistax64.com/tutorials/130095-user-profile-service-failed-logon-user-profile-cannot-loaded.html