Well a url would help here
Like for example if the login thing is in the footer in some custom style you may need to correct that relative file link to full url
If your locking guests down for viewing any content on your site without being logged in then your using
vb standard error templates and same thing need to correct those relative file links to full urls. We dont load or use
vb templates and they are notoriously known for using relative urls and not prefixing any link with their forum url which in my mind is a bug but when your the biggest guy in town you can do what you want.