I have a Maven project (obviously). Several of the dependencies, but not nearly all, have red underscores in the Maven Projects window. If I do a Build/Rebuild Project everything builds fine. From the Maven Projects window if I execute a compile goal it works without error. If I do an external mvn compile it works great If I look in my local maven repository all the files are right where they belong. In short everything except these underscores is perfect.
This is a mature production project, and on other team member's PCs, as well as my old one, it doesn't have this problem. I've read that Intellij will also use the underscore to denote a conflict as well as missing dependency. But conflict doesn't make any more sense than missing.
What steps can I take to further diagnosis this problem, or better yet just fix it?