In Windows 7 & Vista, the User Account Control is enabled by default, to run in Admin approval mode.  Windows Explorer or explorer.exe is also set to run in the standard user context.

Even if you right-click on explorer.exe, and select “Run as Administrator”, it will still run in the standard user context.

The problem is caused by the fact that User Account Control can only elevate an application to a higher token when it is launching a new process.  It cannot elevate an existing process.

When any user logs on, Windows Explorer is already started in the standard user context.  It is always running in the background in order to display your desktop and it cannot be elevated because Windows Explorer is already an existing process.

Windows Explorer was not designed to follow the User Account Control Guidelines for applications that “expect” to run in both contexts: Standard user context and Administrator context.  CMD.exe utility is an example of an application designed to follow User Account Control Guidelines to be run in Standard user context and Administrator context.

If you do not want to be prompted, you can change the security policy setting Behavior of the elevation prompt for administrators in Admin Approval Mode” to “Elevate without Prompting”, recommends KB2273047.  You can also disable User Account Control (UAC).

If you have liked this post, you might want to check out some more, on topics like Administrator, Explorer.