title: mb_substr cant be used on PHP 5.2.6
body: <p>Fatal error:</p>
  
  <blockquote>
    <p>Call to undefined function mb_substr()</p>
  </blockquote>
  
  <p>After moving to my dedicated server (hypervm CP), I got lots of errors.</p>
  
  <p>How do I solve this problem?</p>