This is still an issue for me using Magento 1.9.2.3, same error, and the same fix Ivan provided from Siteground Works.

Alex, hopefully you sorted the cron job in cpanel (Siteground's support would have sorted this quickly for you on a support ticket) but my working cron command is:

php /home/YOURCPANELNAME/public_html/cron.php > /dev/null

or if your magento is in a sub-folder:

php /home/YOURCPANELNAME/public_html/SUBFOLDER/cron.php > /dev/null