When you have IIS 6 with Frontpage extension 2002 and you have installed the FrontPage Extension 2002 to your IIS 6.0 and wish to check the FrontPage Extension Health and recalculate it but you failed to login (Keep on prompt the login page) to the Administrator page after hit on the Administrator page from the FrontPage manage page.
Firstly, please verify if you have used the correct login detail by typing the login password to a notepad at first. If you still failed to login and hit the cancel button where the page redirect you to a unauthenticated page, you may try with the solution as below where to disable the loopback checking.
1. Open the registry editor by hitting the run button and type in regedit.
2. Locate to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa from your Registry Editor.
3. Right click the Lsa and point to new, then select DWORD value.
4. Then you may type in , DisableLoopbackCheck and press enter.
5. Right click the DisableLoopbackCheck and click on the modify.
6. In the Value data box, type 1, and then click OK.
7. Close the registry editor and you might need to restart the Windows.
Retry again and you shall be able to login by now.
References URL: http://support.microsoft.com/default.aspx?scid=kb;en-us;896861
Note 1: You might need to backup your registry before performing any changes.
Note 2: This setting have been fully tested on IIS 6.0 only.