I've installed MediaWiki on an ISP's servers and had no trouble. Recently I built a RedHat box for an internal wiki at work, and URLs of the form
http://internal.domain/index.php/Main_Page
result in a 404 error. I've applied the suggested RewriteEngine rules specified at http://meta.wikipedia.org/wiki/Apache_config#mod_rewrite to a .htaccess file where index.php is, but that didn't help. Any suggestions?