This question already has an answer here:
Warning: file_exists(): open_basedir restriction in effect. File(/usr/share/doc/php-tcpdf/examples/images/) is not within the allowed path(s): (/nhldata/631/106631/data/web:/usr/local/php55/share/pear:/var/tmp/php:/tmp:/usr/local/php55/lib64) in /nhldata/631/106631/data/web/predigerforum/htdocs/wordpress/wp-content/plugins/civicrm/civicrm/packages/tcpdf/tcpdf_autoconfig.php on line 96
I got this message when I initially installed too. The only workaround seemed to be to insert "@" before the file_exists calls in the referenced PHP files...
There must be some kind of configuration error or permissioning problem that I could not find?
I'm running civiCRM 4.6.2 under the latest Wordpress