Update.php does not show status bar. Now what?

I'm trying to update drupal to the latest version. I run the "update.php" script and the "Run updates" screen does not show a status bar. It just hangs there. The only item on the main section of the page is the page title "Updating"... that's it. The database does not update. I'm not sure what to do. I was using drupal 6.10 and I was trying to update to v6.12. Please help.