Unity 5 library error when trying to open project

I keep getting a recurring error when trying to open my project in unity 5.

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If I click try again the error goes away but is quickly replaced by another file in the metadata folder.
Has anyone else had this problem or can anyone shed light on what it may be?

Thanks

Matt

Back up your project first. Then delete the library folder, open in Unity 5 and let unity rebuild it and see if that helps. BACK UP YOUR PROJECT FIRST!