Index: wp-includes/formatting.php
===================================================================
--- wp-includes/formatting.php	(revision 16851)
+++ wp-includes/formatting.php	(working copy)
@@ -249,7 +249,7 @@
 	if ( !empty($shortcode_tags) && is_array($shortcode_tags) ) {
 		$tagnames = array_keys($shortcode_tags);
 		$tagregexp = join( '|', array_map('preg_quote', $tagnames) );
-		$pee = preg_replace('/<p>\\s*?(\\[(' . $tagregexp . ')\\b.*?\\/?\\](?:.+?\\[\\/\\2\\])?)\\s*<\\/p>/s', '$1', $pee);
+		$pee = preg_replace('/<p>\\s*(\\[(' . $tagregexp . ')\\b.*\\](?:.++\\[\\/\\2\\])?)\\s*<\\/p>/sU', '$1', $pee);
 	}
 
 	return $pee;