Dropdown elements submit even when Submit form on selection is set to No

If you notice that your drop-down fields are submitting the form even when you have "Submit form on selection" set to "no" in that fields parameters, try opening up the field in the administrator, and then clicking the "save" button.  Then save the form, and clear the site cache.  This will assure that the database has the proper parameter setting for that field, and should resolve the issue.