diff --git a/phpBB/includes/session.php b/phpBB/includes/session.php
index 232aeab1f7..83639adafa 100644
--- a/phpBB/includes/session.php
+++ b/phpBB/includes/session.php
@@ -165,7 +165,7 @@ class session
 
 		// Garbage collection ... remove old sessions updating user information
 		// if necessary. It means (potentially) 11 queries but only infrequently
-		if ($current_time > $config['session_last_gc'] + $config['session_gc'] && defined('PHPBB_INSTALLED'))
+		if ($current_time > $config['session_last_gc'] + $config['session_gc'])
 		{
 			$this->gc($current_time);
 		}
@@ -365,11 +365,13 @@ class session
 				// last_visit field won't be updated, which I believe should be
 				// the normal behavior anyway
 				$db->sql_return_on_error(TRUE);
+
 				$sql = 'DELETE FROM ' . SESSIONS_TABLE . '
 					USING ' . SESSIONS_TABLE . ' s1, ' . SESSIONS_TABLE . ' s2
 					WHERE s1.session_user_id = s2.session_user_id
 						AND s1.session_time < s2.session_time';
 				$db->sql_query($sql);
+
 				$db->sql_return_on_error(FALSE);
 
 				// Update last visit time
@@ -387,48 +389,51 @@ class session
 				set_config('session_last_gc', $current_time);
 				break;
 
-			// Get expired sessions, only most recent for each user
-			$sql = 'SELECT session_user_id, session_page, MAX(session_time) AS recent_time
-				FROM ' . SESSIONS_TABLE . '
-				WHERE session_time < ' . ($current_time - $config['session_length']) . '
-				GROUP BY session_user_id, session_page';
-			$result = $db->sql_query_limit($sql, 5);
+			default:
 
-			$del_user_id = '';
-			$del_sessions = 0;
-			if ($row = $db->sql_fetchrow($result))
-			{
-				do
+				// Get expired sessions, only most recent for each user
+				$sql = 'SELECT session_user_id, session_page, MAX(session_time) AS recent_time
+					FROM ' . SESSIONS_TABLE . '
+					WHERE session_time < ' . ($current_time - $config['session_length']) . '
+					GROUP BY session_user_id, session_page';
+				$result = $db->sql_query_limit($sql, 5);
+
+				$del_user_id = '';
+				$del_sessions = 0;
+				if ($row = $db->sql_fetchrow($result))
 				{
-					if ($row['session_user_id'] != ANONYMOUS)
+					do
 					{
-						$sql = 'UPDATE ' . USERS_TABLE . '
-							SET user_lastvisit = ' . $row['recent_time'] . ", user_lastpage = '" . $db->sql_escape($row['session_page']) . "' 
-							WHERE user_id = " . $row['session_user_id'];
-						$db->sql_query($sql);
+						if ($row['session_user_id'] != ANONYMOUS)
+						{
+							$sql = 'UPDATE ' . USERS_TABLE . '
+								SET user_lastvisit = ' . $row['recent_time'] . ", user_lastpage = '" . $db->sql_escape($row['session_page']) . "' 
+								WHERE user_id = " . $row['session_user_id'];
+							$db->sql_query($sql);
+						}
+
+						$del_user_id .= (($del_user_id != '') ? ', ' : '') . $row['session_user_id'];
+						$del_sessions++;
 					}
-
-					$del_user_id .= (($del_user_id != '') ? ', ' : '') . $row['session_user_id'];
-					$del_sessions++;
+					while ($row = $db->sql_fetchrow($result));
 				}
-				while ($row = $db->sql_fetchrow($result));
-			}
 
-			if ($del_user_id != '')
-			{
-				// Delete expired sessions
-				$sql = 'DELETE FROM ' . SESSIONS_TABLE . "
-					WHERE session_user_id IN ($del_user_id)
-						AND session_time < " . ($current_time - $config['session_length']);
-				$db->sql_query($sql);
-			}
+				if ($del_user_id != '')
+				{
+					// Delete expired sessions
+					$sql = 'DELETE FROM ' . SESSIONS_TABLE . "
+						WHERE session_user_id IN ($del_user_id)
+							AND session_time < " . ($current_time - $config['session_length']);
+					$db->sql_query($sql);
+				}
 
-			if ($del_sessions < 5)
-			{
-				// Less than 5 sessions, update gc timer ... else we want gc
-				// called again to delete other sessions
-				set_config('session_last_gc', $current_time);
-			}
+				if ($del_sessions < 5)
+				{
+					// Less than 5 sessions, update gc timer ... else we want gc
+					// called again to delete other sessions
+					set_config('session_last_gc', $current_time);
+				}
+				break;
 		}
 
 		return;
@@ -970,7 +975,7 @@ class auth
 	{
 		global $db;
 
-		$where_sql = ($user_id) ? ' WHERE user_id = ' . $user_id : '';
+		$where_sql = ($user_id) ? ' WHERE user_id ' . ((is_array($user_id)) ? ' IN (' . implode(', ', array_map('intval', $user_id)) . ')' : " = $user_id") : '';
 
 		$sql = 'UPDATE ' . USERS_TABLE . "
 			SET user_permissions = ''