The following script :

<?
class titi {
  var $foobar = TRUE;
}
class toto extends titi { }
$object = new titi;
?>

produces :

23:27 [webase3:p2] titi:~/html% php temp.phtml
Content-Type: text/html

temp.phtml:  Freeing 0x080F3E60 (4 bytes), allocated in zend_hash.c on line 185<br>
temp.phtml:  Freeing 0x080F4100 (42 bytes), allocated in zend_hash.c on line 175<br>

Note that the var $foobar = TRUE is important and can only be TRUE or FALSE (the problem doesn't show up with "" or array()).
Note also that the unused line class toto extends titi { } is necessary.