I was in this area Host Settings > Advanced Settings > Friendly URL Settings. I may have accidentally checked the check box that asks "Use Friendly URLs?", and now I'm unable to go into any of my admin or host settings. When I do, the website produced a "DNN Error". The user-facing side of the site seems to be operating fine.
Is it possible to somehow turn this check box back on? I'm not even sure if this is what's causing it exactly, but I was on this page when it happened.