Well done Plumbert!

Your reply to my weird XP fault post has just been tried and appears to
have done the trick on the machine I brought back. All non
administrative users can now logon and get a desktop. Two of the guys
will be going out to the other campus today to give it a try.

Why do Microsoft do this?! Have an update, it'll only bollocks your
machine.

 

There is a Registration folder within the Windows folder. A Windows update
stuffs the permissions on this folder and wipes them all out. So
Administrators should be set to Full Control, The System user should be set
to Full Controll, and Everyone should have Read permissions. None of these
were set. Still strange why admins could logon.

 

Unable to save *little black book*.

Would you like to try corrupting the previous version too?

 

As documented here: http://support.microsoft.com/?kbid=909444. The problem
emerges only if the default permissions on the %windir%\Registration folder
have been changed from the default, because the catalog files within the
folder rely on inheriting their permissions from the folder.