If only by chance you change the language of your form , for example to 'African' and set the Localizable to True then a resource file ,i.e. form1.af.resx is added to your solution folder. I am not sure if you can delete it safely when you are back to default lagnuage and localizable is set to false.
I tried once and the form controls size and locations changed and when buliding the installer it warned of lost resx files...
Any Idea?