version switch 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 that version of php and everything worked. later we ran autorpm with the 'interactive' setting (just downloading and not auto installing) and the php-dependent application broke. when we 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 reinstall of the old version 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!