EDIT: This is a Drupal core issue, not related to this project, as seen here:
http://drupal.org/node/325827
New versions of PHP display the following E_WARNING when listing a list of articles from "feeds" and in other submits:
warning: strtotime(): It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'Europe/Berlin' for 'CET/1.0/no DST' instead in /var/www/vhosts/.../httpdocs/.../profiles/managingnews/modules/contrib/views/handlers/views_handler_filter_date.inc on line 128.
This warning is repeated every time there is an instance of code containing the strtotime() PHP function.
To solve it, you must specify a default timezone into the /sites/default/settings.php file. Just add the following line into it:
ini_set('date.timezone', date_default_timezone_get());
It would solve the errors.