Yii2表单提交无效，浏览器打开下载视图

I have a Problem with my yii2 website. I have over 300 users, now i have two which has Problems submitting the yii2 forms. They tried it for IE11 and Firefox. If they click on submit the browser just wants to download a file called like the current site. you can see a screenshot:

This is one of my forms:

            echo "<div class='row'>";
            $form = ActiveForm::begin(['id' => 'save-form']); 
            echo $form->field($model, 'username')->textInput(['readonly' => true, 'value' => $row['username']]);
            echo $form->field($model, 'benutzertyp')->textInput(['readonly' => true, 'value' => $row['benutzertyp']]);
            echo $form->field($model, 'email')->textInput(['readonly' => false, 'value' => $row['email']]) ;
            echo $form->field($model, 'genre')->textInput(['readonly' => true, 'value' => $row['genre']]) ;
            echo $form->field($model, 'genre')-> listBox(array('Wave'=>'Wave','Rock'=>'Rock','Pop'=>'Pop','Metal'=>'Metal','Punk'=>'Punk','Schlager'=>'Schlager', 'Elektro'=>'Elektro'))->label(false); 

            echo $form->field($model, 'eigenesGenre')->textInput(['readonly' => false, 'value' => $row['eigenesGenre']]) ;
            echo $form->field($model, 'heimatstadt')->textInput(['readonly' => false, 'value' => $row['heimatstadt']]) ;
            echo $form->field($model, 'beschreibung')->textArea(['readonly' => false, 'value' => $row['beschreibung']]) ;
            echo $form->field($model, 'kontakt')->textInput(['readonly' => false, 'value' => $row['kontakt']]) ;
            echo $form->field($model, 'telefon')->textInput(['readonly' => false, 'value' => $row['telefon']])->label("Gib bitte eine Telefonnummer an unter der wir euch erreichen können. (Wird nicht im Profil angezeigt!)") ;
            echo "<div class='form-group'>";
            echo Html::submitButton("speichern", ['class' => 'btn btn-primary ', 'name' => 'speichern']) ;
            echo "</div>";
            ActiveForm::end(); 
            echo "</div>";