Multiple Library Folders Error

Hey guys
I’ve been having an error with my game recently, where I open the project in unity and I get this message:

Fatal error!

Detected multiple Library folders within your project.
Did you copy a project into this project? Use “Export Package” to move assets between projects.
You need to remove the following Library folder(s) from your project before you can open it again:
/Users/myaccountname/unityproject/Assets/Library

I didn’t copy any folders into the project, but I removed the Library from my Assets folder and launched unity, and when I open the scene, all my assets show up, but they’re in red and can’t be seen, and when I try and run the game I get a blank screen.
Can someone please help me with this? I’m using Unity 4 Pro with Mac OS X Mountain Lion, if that helps. I need to have this game back and the Multiplayer/Combat added by Saturday, so could someone please answer quickly?
Thanks
Harry

I’m not sure if this will help. I work with Unity on Windows. Be sure to make a backup before trying this. I had a similar problem. Getting rid of the library folder did not help, which is why I cut it instead of deleting it so I could paste it back in when it didn’t work. I believe I fixed my issue. Apparently there were TWO library folders and TWO project settings folders/files. Based on how I named additional folders (Assets, Prefabs, Scripts) within a folder that I named after myself, Unity thought that the folder they were being held in was a secondary project and so automatically added in a secondary project settings and library folder. After getting rid of the secondary library/project settings folder/files, I renamed the secondary assets/prefabs/ and script folders that I had made. It appears to have worked for me. My project is running fine. I hope it helps anyone else who is reading this.