This suggests that some of Word's registry entries are damaged. You could try deleting the entries and reset all the options that you then lose.
Alternatively, you can run the following pair of auto macros:
Code:
Sub AutoNew()
ActiveWindow.View.FieldShading = 1 'always
End Sub
Sub AutoOpen()
ActiveWindow.View.FieldShading = 1 'always
End Sub
Place the macros in your Normal template. See
http://www.gmayor.com/installing_macro.htm.