I've just extracted the Zenphoto 1.2 files to a directory and visited my site http://192.168.11.23/zenphoto/, the browser stops loading, with no page displayed. When I check the web server logs I find this:

[Sun Sep 21 13:07:29 2008] [error] [client 192.168.11.105] PHP Fatal error: Call to undefined function mysql_error() in /var/www/html/zenphoto/zp-core/setup.php on line 126

I've got apache, php, mysql and php-gd installed on my Fedora 9 box. Other pages and scripts seem to work fine. Any ideas?

That function is a piece of PHP (http://us3.php.net/manual/en/function.mysql-error.php). Perhaps the PHP MySQL support is not properly installed.