title: The Magento catalog price rules disappear sometimes during the day
body: <p>My store is running on magento 1.8.1 CE.</p>
  
  <p>The catalog price rules are working fine and being set every night with a cron.</p>
  
  <p>But sometimes during the day the price rules disappear ... I can solve it again by pressing the set catalog rules, but i am missing a lot of conversion trough this problem.</p>
  
  <p>Does anyone know what is wrong?</p>