The shadercreation UI won't load.

I'm not sure how you handle bugs on previous versions? I'm still on 0.13 (w7-x64 and Unity 4.2.1f4) as I wanted my shaders to continue working. Anyway, as far as I know I haven't changed anything in my project regarding Shaderforge. But now I can no longer open my shaders by clicking the open in Shaderforge button nor start a new shader by launching it under the Window menu and clicking create new shader.
The error Unity displays looks like this:

NullReferenceException: Object reference not set to an instance of an object
ShaderForge.SF_Editor.DrawPreviewPanel (Rect r)
ShaderForge.SF_Editor.OnGUI ()
System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) (at /Applications/buildAgent/work/c514da0c8183631c/mcs/class/corlib/System.Reflection/MonoMethod.cs:222)

Is there anything else I can do to get things working again? I'm tempted to try your new version but I really don't want to loose my old shaders.