For fantastico errors like:

============================
PHP Warning: is_file() [<a href='function.is-file'>function.is-file</a>]: open_basedir restriction in effect. File(/usr/local/cpanel/base/frontend/x3/fantasticoinc.php) is not within the allowed path(s): (/home:/tmp) in /tmp/cpanel_phpengine.1278579677.32441HzpCQXuPrV on line 166
PHP Warning: is_file() [<a href='function.is-file'>function.is-file</a>]: open_basedir restriction in effect. File(/usr/local/cpanel/base/frontend/x3/stdheader.html) is not within the allowed path(s): (/home:/tmp) in /tmp/cpanel_phpengine.1278579677.32441HzpCQXuPrV on line 206
PHP Fatal error: Call to undefined function get_files() in /tmp/cpanel_phpengine.1278579677.32441HzpCQXuPrV on line 609
=============================

Fix:

This should be an issue with cpanel PHP. So run

/scripts/makecpphp