Descriptive Problem Summary:
I went to modify one of my libraries to fix an issue. I do not have this library in my files anymore, so I downloaded it from the site to update it directly. So I opened it up, identified the issues I wanted to fix, and went to try to fix them. I had a file named "hud.dm" already present. I renamed this file to "hud_old.dm" so that I could replace it. I then tried to create a new file named "hud.dm", but it wouldn't create it. It kept booting me back to the old "hud.dm", which is now "hud_old.dm". So it isn't registering that I renamed it properly, I suppose.

Workarounds:
Use a file name not already in use in the library.