Some of you may encounter such error in your HostBill installation.
As the last step of HostBill installation you need to a properly functioning cron job. Create a cron job pointing to the /admin/cron.php file set to run every 5 minutes.
*/5 * * * * php -q /path/to/hb/admin/cron.php
However, sometimes even those settings the Cron error persists. In such situation you need to check your PHP.
PHP is sometimes installed as two separate installations, one for PHP-cli (this one is used by Cron and for manual invocations through SSH), other for apache/web. One for web apparently has ionCube loaders installed, but it may be that PHP-cli doesn't have ionCube enabled.
If you are not sure if PHP-cli has ionCube, you can test this by executing Cron line manually from cli.
Other possible option for wrongly working Cron is a wrong Cron CHMOD. It should be at least 755.