I just upgraded from 5.4.2 to 5.4.2.1. It now has a fatl error. I can't get back to me site and I guess I will have to downgrdae back to 5.4.2 based upon other entires in the forum. What's up?

Below are the errors:

Warning: require(/home/content/68/7400968/html/nadckids/updates/concrete5.4.2.1/concrete/startup/config_check.php) [function.require]: failed to open stream: No such file or directory in /home/content/68/7400968/html/nadckids/updates/concrete5.4.2.1/concrete/dispatcher.php on line 11

Fatal error: require() [function.require]: Failed opening required '/home/content/68/7400968/html/nadckids/updates/concrete5.4.2.1/concrete/startup/config_check.php' (include_path='.:/usr/local/php5/lib/php') in /home/content/68/7400968/html/nadckids/updates/concrete5.4.2.1/concrete/dispatcher.php on line 11

Thanks