I have two sites that I upgraded from Drupal 7.4 to 7.7. One worked fine. But on the second one when I run update.php, it says

1 pending update
menu module

7001 - Rename "Primary Links" and "Secondary Links" to their Drupal 7 equivalents.

But when I run this update, it never finishes. It is stuck in the Run updates step. What do I do?