Script (with custom inspector) Variables Reset on Play

Values assigned to my script’s variables will not persist after hitting the Preview button in Unity 4.3.4f1

I have tried adding the line EditorGUIUtility.SetDirty( target ) to the custom inspector script.

The fields being reset are not of a custom type (ie, even booleans, strings, floats, etc. are losing their values, as well as references to objects in the scene and/or project hierarchy).

In Unity lick on Assets and then on Reimport All. Close Unity and start it again.

It seems that it is not saving the changes of the scripts and it just keeps an old version.