diff --git a/admin_domains.php b/admin_domains.php
index b4706d76..41f36d40 100644
--- a/admin_domains.php
+++ b/admin_domains.php
@@ -147,6 +147,14 @@ if($page == 'domains'
 			if(isset($_POST['send'])
 			   && $_POST['send'] == 'send')
 			{
+				/*
+				 * check for APS packages used with this domain, #110
+				 */
+				if(domainHasApsInstances($id))
+				{
+					standard_error('domains_cantdeletedomainwithapsinstances');
+				}
+
 				$query = 'SELECT `id` FROM `' . TABLE_PANEL_DOMAINS . '` WHERE (`id`="' . (int)$id . '" OR `parentdomainid`="' . (int)$id . '")  AND  `isemaildomain`="1"';
 				$subResult = $db->query($query);
 				$idString = array();
diff --git a/customer_domains.php b/customer_domains.php
index 5ebab6af..cb809bbe 100644
--- a/customer_domains.php
+++ b/customer_domains.php
@@ -183,6 +183,14 @@ elseif($page == 'domains')
 					}
 				}
 
+				/*
+				 * check for APS packages used with this domain, #110
+				 */
+				if(domainHasApsInstances($id))
+				{
+					standard_error('domains_cantdeletedomainwithapsinstances');
+				}
+
 				$log->logAction(USR_ACTION, LOG_INFO, "deleted subdomain '" . $idna_convert->decode($result['domain']) . "'");
 				$result = $db->query("DELETE FROM `" . TABLE_PANEL_DOMAINS . "` WHERE `customerid`='" . (int)$userinfo['customerid'] . "' AND `id`='" . (int)$id . "'");
 				$result = $db->query("UPDATE `" . TABLE_PANEL_CUSTOMERS . "` SET `subdomains_used`=`subdomains_used`-1 WHERE `customerid`='" . (int)$userinfo['customerid'] . "'");
diff --git a/lib/functions/aps/function.domainHasApsInstances.php b/lib/functions/aps/function.domainHasApsInstances.php
new file mode 100644
index 00000000..7b00d50b
--- /dev/null
+++ b/lib/functions/aps/function.domainHasApsInstances.php
@@ -0,0 +1,46 @@
+<?php
+
+/**
+ * This file is part of the Froxlor project.
+ * Copyright (c) 2010 the Froxlor Team (see authors).
+ *
+ * For the full copyright and license information, please view the COPYING
+ * file that was distributed with this source code. You can also view the
+ * COPYING file online at http://files.froxlor.org/misc/COPYING.txt
+ *
+ * @copyright  (c) the authors
+ * @author     Froxlor team <team@froxlor.org> (2010-)
+ * @license    GPLv2 http://files.froxlor.org/misc/COPYING.txt
+ * @package    Language
+ * @version    $Id$
+ */
+
+/**
+ * Function domainHasApsInstances
+ *
+ * Checks if a given domain id
+ * is used for APS instances
+ * (if APS enabled, else always false)
+ *
+ * @param int domain-id
+ *
+ * @return boolean
+ */
+
+function domainHasApsInstances($domainid = 0)
+{
+	global $db, $settings;
+	
+	if($settings['aps']['aps_active'] == '1')
+	{
+		if($domainid > 0)
+		{
+			$instances = $db->query_first("SELECT COUNT(`ID`) AS `count` FROM `" . TABLE_APS_SETTINGS . "` WHERE `Name`='main_domain' AND `Value`='" . (int)$domainid . "'");
+			if((int)$instances['count'] != 0)
+			{
+				return true;
+			}
+		}
+	}
+	return false;
+}
diff --git a/lng/english.lng.php b/lng/english.lng.php
index de0d4848..569f08ce 100644
--- a/lng/english.lng.php
+++ b/lng/english.lng.php
@@ -1354,5 +1354,6 @@ $lng['mysql']['sendinfomail'] = 'Send data via email to me';
 $lng['customer']['mysql_add']['infomail_subject'] = '[Froxlor] New database created';
 $lng['customer']['mysql_add']['infomail_body']['pma'] = "\nYou can access your databases using phpMyAdmin via {URI}\n";
 $lng['customer']['mysql_add']['infomail_body']['main'] = "Hello {CUST_NAME},\n\nyou have just added a new database. Here is the entered information:\n\nDatabasename: {DB_NAME}\nPassword: {DB_PASS}\nDescription: {DB_DESC}\n{PMA_URI}\nYours sincerely, the Froxlor-Team";
+$lng['error']['domains_cantdeletedomainwithapsinstances'] = 'You cannot delete a domain which is used by an installed APS package. You have to uninstall it first.';
 
 ?>
diff --git a/lng/german.lng.php b/lng/german.lng.php
index 47700d52..53bab005 100644
--- a/lng/german.lng.php
+++ b/lng/german.lng.php
@@ -1335,4 +1335,6 @@ $lng['mysql']['sendinfomail'] = 'Send data via email to me';
 $lng['customer']['mysql_add']['infomail_subject'] = '[Froxlor] Neue Datenbank erstellt';
 $lng['customer']['mysql_add']['infomail_body']['pma'] = "\nDie Datenbank kann mit phpMyAdmin via {URI} verwaltet werden.\n";
 $lng['customer']['mysql_add']['infomail_body']['main'] = "Hallo {CUST_NAME},\n\ndu hast gerade eine neue Datenbank angelegt. Hier die angegebenen Informationen:\n\nDatenbankname: {DB_NAME}\nPasswort: {DB_PASS}\nBeschreibung: {DB_DESC}\n{PMA_URI}\nVielen Dank, das Froxlor-Team";
+$lng['error']['domains_cantdeletedomainwithapsinstances'] = 'Sie k&ouml;nnen keine Domain l&ouml;schen, die noch von APS Paketen verwendet wird. L&ouml;schen Sie zuerst alle installierten APS Pakete dieser Domain.';
+
 ?>