External libraries import error

I imported a few libraries (jar files) for my project. It seems that they came in correctly--they are on the sidebar in the external libraries tab, and the error saying that the library doesn't exist is gone BEFORE I run it. However, when I run my project, it says that the given library doesn't exist. I know that this specific library works with another file, so I don't think the library is the issue. One other odd thing is that for this project and this project only I have to re-import the libraries any time I open IntelliJ. Any ideas?