I can second this problem. Amazing as it may sound, MySQL support does not seem to be compiled into the PHP configuration that comes with KNOPPIX 5.0.1 (the CD version). The phpinfo() function does not list the mysql module as installed.

Furthermore, I get strange problems with blank web pages being displayed when trying to start up the Apache2 webserver and surfing to http://localhost. I can't get the webserver to properly serve any HTML page that I place in /var/www (which is the DocumentRoot). A simple PHP file with a call to phpinfo() works, however. MIME/file type problem?

Getting PHP to work in KNOPPIX ought to not be harder than cleanly booting KNOPPIX, starting up MySQL, Apache, and then serving a PHP page with proper MySQL code in it. But this does not work in 5.0.1 (whereas it did in earlier versions, with one or two configuration tweaks), and for me that is a major grievance.