diff -up ./lightbox2.insert.inc.fixregexp ./lightbox2.insert.inc
--- ./lightbox2.insert.inc.fixregexp	2010-05-06 09:13:52.000000000 +0000
+++ ./lightbox2.insert.inc	2010-06-01 13:41:45.000000000 +0000
@@ -15,7 +15,7 @@ function lightbox2_insert_styles() {
   // Reformat CCK formatter ids as Insert style ids.
   foreach ($cck_formatters as $formatter_id => $formatter_info) {
     // Currently only the "imagefield--lightbox2" formatters are implemented as styles.
-    if (preg_match('/^imagefield__lightbox2__([^_]+)__([^_]+)$/', $formatter_id, $matches)) {
+    if (preg_match('/^imagefield__lightbox2__((?:_(?!_)|[^_])+)__((?:_(?!_)|[^_])+)$/', $formatter_id, $matches)) {
       $style_id = 'lightbox2--' . $matches[1] . '--' . $matches[2];
       $insert_styles[$style_id] = $formatter_info;
     }