title: usort(): Array was modified by the user comparison function
body: <p>I have a web application that runs fine on our Linux servers but when running on Mac OS with the Zend Community Edition Server using PHP 5.3 we get the error:</p>
  
  <blockquote>
    <p>usort(): Array was modified by the user comparison function</p>
  </blockquote>
  
  <p>every time a page loads for the first time (it takes about 2 minutes for a page to tick over and load, on the linux servers the page loads in 1 second).</p>
  
  <p>Has anyone else experienced this or has any idea how I can fix the problem, I have tried playing around with PHP and Apache memory settings with no luck.</p>