Enter username and password for http://localhost

Is Problem with Localhost in Firefox

IIS uses Integrated Authentication and by default IE has the ability to use your windows user account...but don't worry, so does Firefox but you'll have to make a quick configuration change.

1) Open up Firefox and type in about:config as the url
2) In the Filter Type in ntlm
3) Double click "network.automatic-ntlm-auth.trusted-uris" and type in localhost and hit enter