General Support: Problems moving servers

I have noticed many sites have the same error message at the head of the page, does anyone know how to fix it and waht it means?

Warning: is_readable() [function.is-readable]: open_basedir restriction in effect. File(../plog-translations/en_US.mo) is not within the allowed path(s): (/var/www/vhosts/adtdealer.co.uk/subdomains/gallery/httpdocs:/tmp) in /var/www/vhosts/adtdealer.co.uk/subdomains/gallery/httpdocs/plog-globals.php on line 32