Ok,
with apache 1.3.x do the following:
Based on a clean (without any php4 configuration) httpd.conf:
At the end of the LoadModule section:
LoadModule php4_module libexec/mod_php4-4.3.4.so
At the end of the AddModule section:
AddModule mod_php4.c
Make sure that mod_dir is activated.
Then:
<IfModule mod_dir.c>
DirectoryIndex index.php index.php4 index.php3 index.html index.htm index.cgi index.php index.shtml
</IfModule>
<IfModule mod_php4.c>
AddType application/x-httpd-php .php .phtml
AddType application/x-httpd-php-source .phps
</IfModule>
Make sure to have all of these directives/blocks outside any Directory or VirtualHost sections and do not add any PHP4 Action/AddHandler directives.
Thomas