It was somethig to do with packaging. After much coffee and swearing, I decided to use the Mandriva package removal tool to remove all php-related packages (of which there were loads, many probably unecessary) then installed just the apache module, the php-mysql module and their dependancies. After this and restarting apache (using /etc/rc.d/init.d/httpd restart) PHP worked. Before this, /var/log/httpd/error_log would contain an entry stating that a child process segfaulted for every attempt to access a php script.
Note that I needed to manually edit the /etc/php.ini file to change the line:
Code:
extension_dir = "/usr/lib/php4/extensions"
to:
Code:
extension_dir = "/usr/lib64/php4/extensions"
to enable the mysql module after installing it as Mandriva uses /usr/lib64 for 64bit lib versions.
Hope this helps!