diff --git a/settings/ajax/setbackgroundjobsmode.php b/settings/ajax/setbackgroundjobsmode.php
index 905b90e645ce9167ccac36796bbe91f97c86c5f8..b0292f3b106184ae5cece0158118c80060a1810e 100644
--- a/settings/ajax/setbackgroundjobsmode.php
+++ b/settings/ajax/setbackgroundjobsmode.php
@@ -26,6 +26,9 @@ require_once('../../lib/base.php');
 OC_Util::checkAdminUser();
 OCP\JSON::callCheck();
 
-OC_Appconfig::setValue( 'core', 'backgroundjobs_mode', $_POST['mode'] );
+$mode = isset( $_POST['mode'] ) ? $_POST['mode'] : '';
+if( $mode == "none" || $mode == "ajax" || $mode == "webcron" || $mode == "cron" ){
+	OC_Appconfig::setValue( 'core', 'backgroundjobs_mode', $_POST['mode'] );
+}
 
 echo 'true';
diff --git a/settings/templates/admin.php b/settings/templates/admin.php
index 937073942704a127638fe3d84662172b399d40d3..8a573a556e3c82f8b3f1eb6b5fba358390b1655f 100755
--- a/settings/templates/admin.php
+++ b/settings/templates/admin.php
@@ -27,14 +27,12 @@ if(!$_['htaccessworking']) {
 
 <fieldset class="personalblock" id="backgroundjobs">
 	<legend><strong><?php echo $l->t('Cron');?></strong></legend>
-	<input type="radio" name="mode" value="none" id="backgroundjobs_none" <?php if( $_['backgroundjobs_mode'] == "none" ){ echo 'checked="checked"'; } ?>>
-	<label for="backgroundjobs_none">None</label><br />
 	<input type="radio" name="mode" value="ajax" id="backgroundjobs_ajax" <?php if( $_['backgroundjobs_mode'] == "ajax" ){ echo 'checked="checked"'; } ?>>
-	<label for="backgroundjobs_ajax">AJAX</label><br />
+	<label for="backgroundjobs_ajax" title="<?php echo t("execute one task with each page loaded"); ?>">AJAX</label><br />
 	<input type="radio" name="mode" value="webcron" id="backgroundjobs_webcron" <?php if( $_['backgroundjobs_mode'] == "webcron" ){ echo 'checked="checked"'; } ?>>
-	<label for="backgroundjobs_webcron">Webcron</label><br />
+	<label for="backgroundjobs_webcron" title="<?php echo t("cron.php is registered at a webcron service"); ?>">Webcron</label><br />
 	<input type="radio" name="mode" value="cron" id="backgroundjobs_cron" <?php if( $_['backgroundjobs_mode'] == "cron" ){ echo 'checked="checked"'; } ?>>
-	<label for="backgroundjobs_cron">Cron</label><br />
+	<label for="backgroundjobs_cron"title="<?php echo t("use systems cron service"); ?>">Cron</label><br />
 </fieldset>
 
 <fieldset class="personalblock">