Index: branches/unlabeled/unlabeled-1.6.2/core/units/permissions/permissions_event_handler.php
===================================================================
diff -u -N -r5618 -r5619
--- branches/unlabeled/unlabeled-1.6.2/core/units/permissions/permissions_event_handler.php	(.../permissions_event_handler.php)	(revision 5618)
+++ branches/unlabeled/unlabeled-1.6.2/core/units/permissions/permissions_event_handler.php	(.../permissions_event_handler.php)	(revision 5619)
@@ -188,14 +188,17 @@
 	 */
 	function OnBeforeDeleteFromLive(&$event)
 	{
-		$foreign_keys = $event->getEventParam('foreign_key');
+		if ($event->Prefix == 'c-perm') {
+			// only when saving category permissions, not group permissions
+			$foreign_keys = $event->getEventParam('foreign_key');
 		
-		if ((count($foreign_keys) == 1) && ($foreign_keys[0] == 0)) {
-			// parent item has zero id
-			$temp_object =& $this->Application->recallObject('c');
-			if ($temp_object->isLoaded()) {
-				// category with id = 0 found in temp table
-				$event->status = erFAIL;
+			if ((count($foreign_keys) == 1) && ($foreign_keys[0] == 0)) {
+				// parent item has zero id
+				$temp_object =& $this->Application->recallObject('c');
+				if ($temp_object->isLoaded()) {
+					// category with id = 0 found in temp table
+					$event->status = erFAIL;
+				}
 			}
 		}
 	}