Ever since I reinstalled Snow Leopard on my Mac, i've had some serious Apache issues. Judging from this diagnostic information:

httpd: Syntax error on line 54 of /private/etc/apache2/httpd.conf: Cannot load /private/etc/apache2/libexec/apache2/mod_authn_file.so into server: dlopen(/private/etc/apache2/libexec/apache2/mod_authn_file.so, 10): image not found

...it appears that a linkage of some sort is missing. I'm wondering if I need to reinstall Apache altogether, and if so, how would I install it so that it is configured as by Snow Leopard? (I believe Snow Leopard installs it in a non-standard way.)  Thanks.