On multi page forms, the WPML plugin is causing the Previous and Next buttons to say "Array".

Locate the file wp-content/plugins/gravity-forms-multilingual/inc/gravity_forms_multilingual.class.php
Change the following two lines (line 165,166):
 

$form['fields'][$id]['nextButton']['text'] = icl_t('gravity_form', $form['id'] . '_field-' . $field['id'] . '-nextButton', $field['nextButton']);
$form['fields'][$id]['previousButton']['text'] = icl_t('gravity_form', $form['id'] . '_field-' . $field['id'] . '-previousButton', $field['previousButton']);

To:

$form['fields'][$id]['nextButton']['text'] = icl_t('gravity_form', $form['id'] . '_field-' . $field['id'] . '-nextButton', $field['nextButton']['text']);
$form['fields'][$id]['previousButton']['text'] = icl_t('gravity_form', $form['id'] . '_field-' . $field['id'] . '-previousButton', $field['previousButton']['text']);

Solution documented here

http://wpml.org/forums/topic/wpml-gravity-forms-conflict-previous-and-next-buttons-say-array/