please help! version switching problem

redhat linux 7.3 apache 1.3.27 mysql 3.23.49 php 4.0.4pl1 (static install) mod_ssl-2.8.12 the box had php 4.2.3 installed on it originally. we had a mysql application that would only run with php version 4.0.4pl1 so we installed the old version of php and everything worked. then we ran autorpm with the 'interactive' setting (just downloading and not auto installing) and the application broke. when I run debug_phpinfo it says version 4.2.3. we have reinstalled php version 4.0.4pl1 and debug_phpinfo still says version 4.2.3 and the app. remains broken. yes we copied the php.ini file after the install. we checked the new php binary and its definitely version 4.0.4pl1. we're pulling our hair out. what are we doing wrong/do we have yet to do? thanks!