Borrowed from a Google User Group when I did e search in groups.google.com using:

not “asp pages”

A common problem when ASP pages do not display (but html
pages do) is that the password of the IIS
IWAM_computername user is not syncing properly. 
Authentication/permissions to ASP pages is a complex area,
but this particular problem is easy to remedy and, I
think, well worth trying.  To check this, do the following.

   1.)  Temporarily assign the IIS anonymous accounts
(IUSR_computername and IWAM_computername) to the machine’s
Administrator group. For Win 2K, do this as follows:
          a.) Go to Settings, Control Panel, select
Administrative Tools.
          b.) Double-click ‘Computer Management’,
expand ‘Local Users and Groups’, double-click ‘Users’.
          c.) Select (double-click) IUSR_computer name
account, select ‘Member of’ tab, click ‘Add’ button,
highlight ‘Administrator’ (group), click ‘Apply’.
          d.) Repeat above procedure for IWAM_computer
name account.

    2.) Navigate to the following file –
C:\Inetpub\AdminScripts\synciwam.vbs
Execute this file by double-clicking it.  The hourglass
will display momentarily and then disappear.  No other
indication of the program running will appear.

     3.)  Reboot the workstation. If this was indeed the
problem, ASP pages should now render fine.

     4.)  Don’t forget to remove the IIS anonymous
accounts from the Administrator group.