diff --git a/admin/admin-cli.php b/admin/admin-cli.php
index e2da0c7e7d..18069bd564 100755
--- a/admin/admin-cli.php
+++ b/admin/admin-cli.php
@@ -89,6 +89,31 @@ switch($action)
 		return list_exit_codes();
 
 	default:
+		// we allow to call admin_cmd classes directly, if they define the constant SETUP_CLI_CALLABLE
+		if (substr($action,0,2) == '--' && class_exists($class = str_replace('-','_',substr($action,2))) &&
+			is_subclass_of($class,'admin_cmd') && @constant($class.'::SETUP_CLI_CALLABLE'))
+		{
+			$args = array();
+			$args['domain'] = array_shift($arg0s);	// domain must be first argument, to ensure right domain get's selected in header-include
+			foreach($arg0s as $arg)
+			{
+				list($name,$value) = explode('=',$arg,2);
+				if(property_exists('admin_cmd',$name))		// dont allow to overwrite admin_cmd properties
+				{
+					throw new egw_exception_wrong_userinput(lang("Invalid argument '%1' !!!",$arg),90);
+				}
+				if (substr($name,-1) == ']')	// allow 1-dim. arrays
+				{
+					list($name,$sub) = explode('[',substr($name,0,-1),2);
+					$args[$name][$sub] = $value;
+				}
+				else
+				{
+					$args[$name] = $value;
+				}
+			}
+			return run_command(new $class($args));
+		}
 		usage($action);
 		break;
 }
diff --git a/admin/inc/class.admin_cmd_check_cats.inc.php b/admin/inc/class.admin_cmd_check_cats.inc.php
new file mode 100644
index 0000000000..ac171ba460
--- /dev/null
+++ b/admin/inc/class.admin_cmd_check_cats.inc.php
@@ -0,0 +1,54 @@
+<?php
+/**
+ * EGroupware admin - admin command: check categories for not (longer) existing accounts
+ *
+ * @link http://www.egroupware.org
+ * @author Ralf Becker <RalfBecker-AT-outdoor-training.de>
+ * @package admin
+ * @copyright (c) 2012 by Ralf Becker <RalfBecker-AT-outdoor-training.de>
+ * @license http://opensource.org/licenses/gpl-license.php GPL - GNU General Public License
+ * @version $Id$
+ */
+
+/**
+ * admin command: check categories for not (longer) existing accounts
+ */
+class admin_cmd_check_cats extends admin_cmd
+{
+	const SETUP_CLI_CALLABLE = true;
+
+	/**
+	 * Constructor
+	 *
+	 * @param array $data=array() default parm from parent class, no real parameters
+	 */
+	function __construct($data=array())
+	{
+		admin_cmd::__construct($data);
+	}
+
+	/**
+	 * give or remove run rights from a given account and application
+	 *
+	 * @param boolean $check_only=false only run the checks (and throw the exceptions), but not the command itself
+	 * @return string success message
+	 */
+	protected function exec($check_only=false)
+	{
+		if ($check_only) return true;
+
+		admin_cmd::_instanciate_accounts();
+
+		return lang("%1 categories of not (longer) existing accounts deleted.", categories::delete_orphans());
+	}
+
+	/**
+	 * Return a title / string representation for a given command, eg. to display it
+	 *
+	 * @return string
+	 */
+	function __tostring()
+	{
+		return lang('Check categories for not (longer) existing accounts');
+	}
+}
diff --git a/phpgwapi/inc/class.accounts.inc.php b/phpgwapi/inc/class.accounts.inc.php
index 07140d41f8..61738c03d1 100644
--- a/phpgwapi/inc/class.accounts.inc.php
+++ b/phpgwapi/inc/class.accounts.inc.php
@@ -529,10 +529,13 @@ class accounts
 
 		$this->backend->delete($id);
 
+		self::cache_invalidate($invalidate);
+
 		// delete all acl_entries belonging to that user or group
 		$GLOBALS['egw']->acl->delete_account($id);
 
-		self::cache_invalidate($invalidate);
+		// delete all categories belonging to that user or group
+		$GLOBALS['egw']->cats->delete_account($id);
 
 		return true;
 	}
diff --git a/phpgwapi/inc/class.categories.inc.php b/phpgwapi/inc/class.categories.inc.php
index a96e6ca773..eaa7aba109 100644
--- a/phpgwapi/inc/class.categories.inc.php
+++ b/phpgwapi/inc/class.categories.inc.php
@@ -129,7 +129,7 @@ class categories
 		$this->app_name		= $app_name;
 		$this->db			= $GLOBALS['egw']->db;
 
-		if (is_null(self::$cache))	// sould not be necessary, as cache is load and restored by egw object
+		if (is_null(self::$cache))	// should not be necessary, as cache is load and restored by egw object
 		{
 			self::init_cache();
 		}
@@ -994,6 +994,77 @@ class categories
 		}
 	}
 
+	/**
+	 * Delete categories belonging to a given account, when account got deleted
+	 *
+	 * @param int $account_id
+	 * @param int $new_owner=null for users data can be transfered to new owner
+	 * @return int number of deleted or modified categories
+	 */
+	public static function delete_account($account_id, $new_owner=null)
+	{
+		if (is_null(self::$cache)) self::init_cache();
+
+		$deleted = 0;
+		foreach(self::$cache as $cat_id => $data)
+		{
+			if ($data['owner'] && ($owners = explode(',', $data['owner'])) && ($owner_key = array_search($account_id, $owners)) !== false)
+			{
+				// delete category if account_id is single owner and no new owner or owner is a group
+				if (count($owners) == 1 && (!$new_owner || $account_id < 0))
+				{
+					if (!isset($cat))
+					{
+						$cat = new categories($new_owner, $data['appname']);
+					}
+					$cat->delete($cat_id, false, true);
+				}
+				else
+				{
+					unset($owners[$owner_key]);
+					if ($new_owner && $account_id > 0) $owners[] = $new_owner;
+					$data['owner'] = implode(',', $owners);
+					// app_name have to match cat to update!
+					if (!isset($cat) || $cat->app_name != $data['appname'])
+					{
+						$cat = new categories($new_owner, $data['appname']);
+					}
+					$cat->add($data);
+				}
+				++$deleted;
+			}
+		}
+		return $deleted;
+	}
+
+	/**
+	 * Delete categories with not (longer) existing owners
+	 *
+	 * @return int number of deleted categories
+	 */
+	public static function delete_orphans()
+	{
+		if (is_null(self::$cache)) self::init_cache();
+
+		$checked = array();
+		$deleted = 0;
+		foreach(self::$cache as $cat_id => $data)
+		{
+			foreach(explode(',', $data['owner']) as $owner)
+			{
+				if ($owner && !in_array($owner, $checked))
+				{
+					if (!$GLOBALS['egw']->accounts->exists($owner))
+					{
+						$deleted += self::delete_account($owner);
+					}
+					$checked[] = $owner;
+				}
+			}
+		}
+		return $deleted;
+	}
+
 	/**
 	 ******************************** old / deprecated functions ***********************************
 	 */