http 404 error for other php pages

NOW the URLS such as http://localhost/manual/new_features_1_3.html and http://localhost/index.html.en etc. are available on IE 5.0 to me. But the site named "try" still doesn't work.(ie. the URL http://loaclhost/try/index.php still gets HTTP 404 ERROR, the same question occured on some other sites under the localhost. The sites are edited with Frontpage 2k Please give me some advice to resolve it! THANKS Baker