title: errors in admin area after updating to joomla 2.5
body: <p>I updated my joomla site to 2.5 from joomla 1.7 I faced below errors:</p>
  
  <p>1- I cannot open global configuration page from the admin area and receive "500 internal server error"
  2- When I press the add new article button from the admin area I receive the same error.
  3- When I press the add new category button from the admin area I receive the same error.</p>
  
  <p>appreciate if you can help to solve this.</p>