Fatal error all of a sudden

I was simply adding catagories to get the site organized and all of a sudden I get:

Warning: require(/usr/local/ndn/web/oneclicks/wordpress/wp-includes/class.wp-dependencies.php) [function.require]: failed to open stream: No such file or directory in /usr/local/ndn/web/oneclicks/wordpress/wp-includes/script-loader.php on line 3

Fatal error: require() [function.require]: Failed opening required ‘/usr/local/ndn/web/oneclicks/wordpress/wp-includes/class.wp-dependencies.php’ (include_path=’/usr/local/lib/php:/ndn/web/squirrelmail-1.2.7/plugins’) in /usr/local/ndn/web/oneclicks/wordpress/wp-includes/script-loader.php on line 3

I was not doing anything with the files on the server at all. Dreamhost is the host.