I've been a long time lurker but finally had to post this, I've got several site collections on my server. Each with their own port. We had a contractor come in and set up one of the site collections with SSL/alternate access mapping and everything was working great. I'm not sure if someone in my department was tweaking settings or what happend but now the site wont allow me to sign in to make changes. As soon as I click sign-in it immediately goes to a http 401.1 Unauthorized access (I don't even have a chance to submit my credentials). I've looked for errors and and haven't seen anything in regards to this. I went to central admin and it appears the only difference between this site collection and the others is that it is different in the Alternate access mappings.
You can see for yourself at the bottom: https://apply.alaskapacific.edu/ at the bottom because as I stated it doesn't even require credentials to kick up this error.
EDIT: It does prompt for credentials, once it has it it doesn't pass it through.