Loading script assembly "..." failed!

Hi , I'm trying to build my game to webplayer but everytime I try these errors pop's up :

"Loading script assembly "Library/ScriptAssemblies/Assembly-CSharp.dll" failed!" and "Loading script assembly "Library/ScriptAssemblies/Assembly-CSharp-Editor.dll" failed!"

And it seems all my scripts are removed from all the stuff I made.

Is there a fix for this?

I use Unity pro and a free version of NGUI.

Thanks.