Hello,
You may need to check if your have your full LAMP server installed: LAMP stands for:
Linux
Apache "Apache web server"
Mysql "Mysql server"
PhP "modules and configuration files for everything to work"
Now you may be able to go back and install your LAMP server using Mandrake package manager installer. I'm not to sure about Mandrake because I stopped using Mandrake a while ago. But I would suggest that you may see if everything is installed. You can do this from the command line easily.
updatedb "this will run for a while as it indexes your file system"
locate apache2
locate mysql
locate php.ini
locate php
Do these and see what you have. Also you may take a look at this
http://www.howtoforge.com/perfect_setup_mandriva_2006
http://www.howtoforge.com/perfect_setup_mandriva_2007
And This
http://www.php.net/phpinfo
Blessings