Index: wp-includes/functions.php
===================================================================
--- wp-includes/functions.php	(revision 3657)
+++ wp-includes/functions.php	(working copy)
@@ -261,14 +261,37 @@
 	return 0;
 }
 
-
+/*
 function maybe_unserialize($original) {
 	if ( false !== $gm = @ unserialize($original) )
 		return $gm;
 	else
 		return $original;
 }
+*/
 
+function maybe_unserialize($original) {
+	if ( is_serialized($original) )
+		if ( false !== $gm = @ unserialize($original) )
+			return $gm;
+	return $original;
+}
+
+function is_serialized($data) {
+	if ( !is_string($data) ) {
+		// if it isn't a string, it isn't serialized
+		return false;
+	}
+	$data = trim($data);
+	if ( preg_match("/^(a|d|o|b|i|s):[0-9]+:(.*)[;}]/si",$data) )
+		return true;
+	return false;
+}
+
+function throw_serialization_error($data) {
+	die(__('<strong>Error:</strong> serialized data was detected!'));
+}
+
 /* Options functions */
 
 function get_settings($setting) {
@@ -348,7 +371,7 @@
 	return apply_filters('all_options', $all_options);
 }
 
-function update_option($option_name, $newvalue) {
+function update_option($option_name, $newvalue, $accept_serialized=false) {
 	global $wpdb;
 
 	if ( is_string($newvalue) )
@@ -365,8 +388,7 @@
 		return true;
 	}
 
-	if ( is_array($newvalue) || is_object($newvalue) )
-		$newvalue = serialize($newvalue);
+	$newvalue = prepare_data($newvalue, $accept_serialized);
 
 	wp_cache_set($option_name, $newvalue, 'options');
 
@@ -395,8 +417,7 @@
 	if ( false !== get_option($name) )
 		return;
 
-	if ( is_array($value) || is_object($value) )
-		$value = serialize($value);
+	$value = prepare_data($value);
 
 	wp_cache_set($name, $value, 'options');
 
@@ -418,6 +439,16 @@
 	return true;
 }
 
+function prepare_data($data, $accept_serialized=false) {
+	if ( is_string($data) )
+		$data = trim($data);
+	elseif ( is_array($data) || is_object($data) )
+		return serialize($data);
+	if ( !$accept_serialized && is_serialized($data) )
+		throw_serialization_error($data);
+	return $data;
+}
+
 function add_post_meta($post_id, $key, $value, $unique = false) {
 	global $wpdb, $post_meta_cache;
 
@@ -431,6 +462,8 @@
 	$original = $value;
 	if ( is_array($value) || is_object($value) )
 		$value = $wpdb->escape(serialize($value));
+	else
+		$value = prepare_data($value);
 
 	$wpdb->query("INSERT INTO $wpdb->postmeta (post_id,meta_key,meta_value) VALUES ('$post_id','$key','$value')");
 
@@ -510,6 +543,8 @@
 	$original_value = $value;
 	if ( is_array($value) || is_object($value) )
 		$value = $wpdb->escape(serialize($value));
+	else
+		$value = prepare_data($value);
 
 	$original_prev = $prev_value;
 	if ( is_array($prev_value) || is_object($prev_value) )
@@ -2165,9 +2200,7 @@
 		return false;
 	$meta_key = preg_replace('|[^a-z0-9_]|i', '', $meta_key);
 
-	if ( is_array($meta_value) || is_object($meta_value) )
-		$meta_value = serialize($meta_value);
-	$meta_value = trim( $meta_value );
+	$meta_value = prepare_data($meta_value);
 
 	if (empty($meta_value)) {
 		delete_usermeta($user_id, $meta_key);
@@ -2197,9 +2230,7 @@
 		return false;
 	$meta_key = preg_replace('|[^a-z0-9_]|i', '', $meta_key);
 
-	if ( is_array($meta_value) || is_object($meta_value) )
-		$meta_value = serialize($meta_value);
-	$meta_value = trim( $meta_value );
+	$meta_value = prepare_data($meta_value);
 
 	if ( ! empty($meta_value) )
 		$wpdb->query("DELETE FROM $wpdb->usermeta WHERE user_id = '$user_id' AND meta_key = '$meta_key' AND meta_value = '$meta_value'");
Index: wp-admin/admin-functions.php
===================================================================
--- wp-admin/admin-functions.php	(revision 3657)
+++ wp-admin/admin-functions.php	(working copy)
@@ -226,7 +226,8 @@
 	// Meta Stuff
 	if ($_POST['meta']) {
 		foreach ($_POST['meta'] as $key => $value)
-			update_meta($key, $value['key'], $value['value']);
+			if ( '%SERIALIZED_DATA%' != $value )
+				update_meta($key, $value['key'], $value['value']);
 	}
 
 	if ($_POST['deletemeta']) {
@@ -849,6 +850,10 @@
 			$style = '';
 		if ('_' == $entry['meta_key'] { 0 })
 			$style .= ' hidden';
+		if ( is_serialized($entry['meta_value']) ) {
+			-- $count;
+			continue;
+		}
 		echo "
 			<tr class='$style'>
 				<td valign='top'><input name='meta[{$entry['meta_id']}][key]' tabindex='6' type='text' size='20' value='{$entry['meta_key']}' /></td>
@@ -920,7 +925,10 @@
 
 	$metakeyselect = $wpdb->escape(stripslashes(trim($_POST['metakeyselect'])));
 	$metakeyinput = $wpdb->escape(stripslashes(trim($_POST['metakeyinput'])));
-	$metavalue = $wpdb->escape(stripslashes(trim($_POST['metavalue'])));
+	$metavalue = prepare_data(stripslashes((trim($_POST['metavalue']))));
+	if ( '%SERIALIZED_DATA%' == $metavalue )
+		return;
+	$metavalue = $wpdb->escape($metavalue);
 
 	if ( ('0' === $metavalue || !empty ($metavalue)) && ((('#NONE#' != $metakeyselect) && !empty ($metakeyselect)) || !empty ($metakeyinput)) ) {
 		// We have a key/value pair. If both the select and the 
@@ -948,7 +956,8 @@
 
 function update_meta($mid, $mkey, $mvalue) {
 	global $wpdb;
-
+	if ( is_serialized(stripslashes($mvalue)) )
+		return false;
 	return $wpdb->query("UPDATE $wpdb->postmeta SET meta_key = '$mkey', meta_value = '$mvalue' WHERE meta_id = '$mid'");
 }
 
Index: wp-admin/options.php
===================================================================
--- wp-admin/options.php	(revision 3657)
+++ wp-admin/options.php	(working copy)
@@ -33,7 +33,8 @@
 
 	if (!$_POST['page_options']) {
 		foreach ($_POST as $key => $value) {
-			$options[] = $key;
+			if ( $value != '%SERIALIZED_DATA%')
+				$options[] = $key;
 		}
 	} else {
 		$options = explode(',', stripslashes($_POST['page_options']));
@@ -95,11 +96,17 @@
 $options = $wpdb->get_results("SELECT * FROM $wpdb->options ORDER BY option_name");
 
 foreach ($options as $option) :
-	$value = wp_specialchars($option->option_value);
+	if ( is_serialized($option->option_value) ) {
+		$value = '%SERIALIZED_DATA%';
+		$disabled = ' disabled="disabled"';
+	} else {
+		$value = wp_specialchars($option->option_value);
+		$disabled = '';
+	}
 	echo "
 <tr>
 	<th scope='row'><label for='$option->option_name'>$option->option_name</label></th>
-	<td><input type='text' name='$option->option_name' id='$option->option_name' size='30' value='" . $value . "' /></td>
+	<td><input type='text' name='$option->option_name' id='$option->option_name' size='30' value='" . $value . "'$disabled /></td>
 	<td>$option->option_description</td>
 </tr>";
 endforeach;