How to close a Visual Basic application with multiple forms?

I'm a beginner with visual basic. In two of the three forms on my application, I made ons which use .close to exit all the forms. This doesn't seem to work because it says it is still debugging. I've tried disposing them to but that doesn't work. It works when I click it when it first opens the form but if I go to the other form (which has a main menu on which closes itself and the other form, and opens and disposes the menu form (the first form). Is my problem here or did I do something else wrong?