IIS 6.0 and Frontpage server ext 2002

Plateform: Windows 2003 server

We host an intranet that required credentials to view. (domain\username) I accidentally ran the 'detect and repair' option in 'check server' health. I think what hosed it up was the 'tighten security' option.

Now nobody except Domain\enterprise admins can login sucessfully. The credentials box comes up after entering url for intranet for regular users but will not take the domain users credentials.

Where should I begin looking?