diff --git a/phpBB/includes/functions.php b/phpBB/includes/functions.php
index de1f7064e8..d293157bd7 100644
--- a/phpBB/includes/functions.php
+++ b/phpBB/includes/functions.php
@@ -35,8 +35,9 @@ function set_config($config_name, $config_value, $is_dynamic = FALSE)
 	}
 	else
 	{
-		$db->sql_query('DELETE FROM ' . CONFIG_TABLE . " 
-			WHERE config_name = '" . $config_name . "'");
+		$sql = 'DELETE FROM ' . CONFIG_TABLE . " 
+			WHERE config_name = '$config_name'";
+		$db->sql_query($sql);
 
 		$sql = 'INSERT INTO ' . CONFIG_TABLE . " (config_name, config_value)
 			VALUES ('$config_name', '" . $db->sql_escape($config_value) . "')";
diff --git a/phpBB/includes/functions_display.php b/phpBB/includes/functions_display.php
index d65fe44c19..c9a69b1349 100644
--- a/phpBB/includes/functions_display.php
+++ b/phpBB/includes/functions_display.php
@@ -55,8 +55,8 @@ function display_forums($root_data = '', $display_moderators = TRUE)
 		$lastread_select = '';
 		$sql_lastread = '';
 
-		$tracking_forums = (isset($_COOKIE[$config['cookie_name'] . '_f'])) ? unserialize($_COOKIE[$config['cookie_name'] . '_f']) : array();
-		$tracking_topics = (isset($_COOKIE[$config['cookie_name'] . '_t'])) ? unserialize($_COOKIE[$config['cookie_name'] . '_t']) : array();
+		$tracking_forums = (isset($_COOKIE[$config['cookie_name'] . '_f'])) ? unserialize(stripslashes($_COOKIE[$config['cookie_name'] . '_f'])) : array();
+		$tracking_topics = (isset($_COOKIE[$config['cookie_name'] . '_t'])) ? unserialize(stripslashes($_COOKIE[$config['cookie_name'] . '_t'])) : array();
 	}
 
 	$sql = "SELECT f.* $lastread_select 
diff --git a/phpBB/includes/functions_posting.php b/phpBB/includes/functions_posting.php
index 7ae621ed6e..24284032ea 100644
--- a/phpBB/includes/functions_posting.php
+++ b/phpBB/includes/functions_posting.php
@@ -1173,7 +1173,7 @@ function submit_post($mode, $message, $subject, $username, $topic_type, $bbcode_
 		
 	// Mark this topic as read and posted to.
 	$mark_mode = ($mode == 'post' || $mode == 'reply' || $mode == 'quote') ? 'post' : 'topic';
-	markread($mark_mode, $post_data['forum_id'], $post_data['topic_id'], $post_data['post_id']);
+	markread($mark_mode, $post_data['forum_id'], $post_data['topic_id'], $post_data['post_time']);
 
 	$db->sql_transaction('commit');
 
diff --git a/phpBB/viewforum.php b/phpBB/viewforum.php
index 25c88712fd..12b72b5bae 100644
--- a/phpBB/viewforum.php
+++ b/phpBB/viewforum.php
@@ -519,7 +519,7 @@ if ($forum_data['forum_type'] == FORUM_POST)
 
 			if ($config['load_db_lastread'])
 			{
-				if ($row['mark_time'] > $row['topic_last_post_time'] && !isset($update_forum))
+				if ($row['mark_time'] >= $row['topic_last_post_time'] && !isset($update_forum))
 				{
 					$update_forum = true;
 				}
@@ -530,7 +530,7 @@ if ($forum_data['forum_type'] == FORUM_POST)
 			}
 			else
 			{
-				if ($tracking_topics[$topic_id] > $row['topic_last_post_time'] && !isset($update_forum))
+				if ($tracking_topics[$topic_id] >= $row['topic_last_post_time'] && !isset($update_forum))
 				{
 					$update_forum = true;
 				}
@@ -549,7 +549,7 @@ if ($forum_data['forum_type'] == FORUM_POST)
 	// after reading a topic
 	if ($user->data['user_id'] != ANONYMOUS && $update_forum)
 	{
-		markread('mark', $forum_id);
+		markread('mark', $forum_id, false, time());
 	}
 }