Why can't I create a site or sign in as a different user?

I ran into this problem this morning and I must admit, I was freaking out just a little bit! I am a Farm Administrator on SharePoint in its entirety so I don't have to worry about permissions, like, ever!

So when I tried to create a new SubSite under one of my site collections and I was getting nothing, I was a little stumped! As I was logged into SharePoint as myself, I tried to sign in as a different user, aka the general SharePoint adminstrator but that wasn't allow me to do so. I was getting a message saying "404 Unauthorized!" WHAT?

I am the one and only SharePoint admin on site so nobody else would have been tampering with my account or anything really as they wouldn't even know how to. So I signed into one of my servers as the Admin account and that was working fine. I double checked my permissions and they were fine.

Then it dawned on me! My password was changed that morning and I hadn't refreshed it (aka logged out and in again). So I did that and it worked.

Cue slap in my face.