title: Magento: Fatal error: Class 'Mage_Catalogrule_Helper_Data' not found
body: <p>I just made a few changes to my webshop by admininterface (no big one, like no short media URL..) and now every time I log in to Magento it shows up the following Error. I can't see anything else. The frontend is still working.</p>
  
  <blockquote>
    <p>Fatal error: Class 'Mage_Catalogrule_Helper_Data' not found in /var/www/vhosts/mysite.com/httpdocs/app/Mage.php on line 546</p>
  </blockquote>
  
  <p>What could be the matter and how can I fix it? Would be great if somebody could help me.</p>
  
  <p>thanks</p>