I have the same scenario as this question, but with a different problem:
ASP.Net MVC Ajax form with jQuery validation
I've set the AjaxOptions.OnBegin property to call return $('form').validate().form(); which works fine for when validation fails; the validation messages are displayed and the form is not posted. However, since setting AjaxOptions.OnBegin, I now get a full page refresh rather than an Ajax call when there are no validation errors. It only happens if AjaxOptions.OnBegin is set. Any ideas?