title: Exception in Magento 1.5.0.1
body: <p>I get an error message in the bottom of the page :</p>
  
  <blockquote>
    <p>Fatal error: Uncaught exception 'Exception' with message
    'Serialization of 'Mage_Core_Model_Layout_Element' is not allowed' in
    [no active file]:0 Stack trace: #0 {main} thrown in [no active file]
    on line 0</p>
  </blockquote>
  
  <p>Problem is i don't get any file or line number. 
  Have you seen this before? Where can I start to fix it?</p>
  
  <p>I searched on google and found <a href="https://stackoverflow.com/questions/6422876/serialization-not-allowed-in-magento">this</a> answer but the response is not valid in my case. Didn't find any other response, probably because of large number of websites that display this error.</p>