You might want to try tailing your error_log to see what happens when you visit the Web page.
tail -f /var/log/httpd/error_log
Hit enter a few times to make some empty lines in the log output. While that's running, reload the Web page that gives you that error. Then go back to the tail and stop it [CTRL-C]. Check out what the logs say. Paste them here if you want to.