Some time ago I wrote about a misconception so common that it might pass as an IT legend – the confusion of HKU\.Default with the default user’s registry hive.
Recently I came across another interesting misapprehension. As you know, the profiles base directory (usually C:\Documents and Settings) contains not only one special sub-folder, Default User, but also All Users, whose purpose is well-known: When Explorer builds the start menu and the desktop it pulls entries both from the logged-on user’s profile and from the all users folder. That is, by the way, the reason why standard users (i.e. non-admins) cannot modify some of the icons on the desktop and in the start menu – those that reside in the All Users folder, which is writeable only for administrators.
We all agree that files and folders inside the All Users “profile” have their right to exist – but what about a registry hive? Yes, that’s right. The so-called “All Users Profile”, which is not a profile at all, has its own registry hive, just like any other user profile. What could that be used for, you might wonder? Well, at least I did. A quick search on the net revealed wondrous capabilities for user environment customization allegedly built right into Windows since Day 1. According to most of the articles dealing with All User’s NTUser.dat, changes made inside that file by loading it into the registry, making the changes and unloading it, are to affect every user logging on.
This is, of course, entirely wrong. I tried it out, just to be on the safe side. I put some registry keys and values inside the all users hive, logged on with a brand-new user and – nothing happened.
At this point in the discussion it is valid to ask what the purpose of that mysterious registry file in the folder All Users might be. To be honest, I have not the slightest clue. What I do know, though, is that the hive is not used. It is, in fact, so utterly useless that it has simply been removed in Windows Vista and Server 2008.