Error when creating new script - MonoDevelop - Could not find Assembly-UnityScript.unityproj

When using the free version of unity3d, while making a game, I added a script to add movement to a sprite. When opening that script in monodevelop, I got the following error:

Assembly-UnityScript (load failed)

Could not find file "/Users/nameremoved/Desktop/Devloper/C:C++:Obj-C:C#/Game Dev/Pong/Assembly-UnityScript.unityproj"

I am using Unity 4.3.4 on an iMac running OS X Mavericks.

I was following this tutorial at the time: http://youtu.be/hCysoAoV3dc

The file, when I created it, was in javascript, but at the top of the selection tool bar to the right of MonoDevelop, it describes it as being c sharp?

Screenshot:

There are also errors inside Unity:

Screenshot:

Have I done something wrong or is it a bug?

Thanks in advance,

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