When using new C($a = new A()) instead of new C(new A()) the code seems to work like expected.

Shorter reproduce script. It shows that removing one reference with setting the variable holding it to NULL deletes the object thus leaving one reference handing. In the script of the original reporter this interferes with a creation of a new object of the class of the innormally deleted one and the new objects hooks on the nirvana reference created by the bug.
<?php
new C(new A("FUBAR"));

class A {
    public $text;
    
    function __construct($m){
        $this->text = $m;
    }
}


class C {
    public $e;
    public $e2;
    
    function __construct($elem){
        $this->e = $elem;
	$this->e2 = $elem;
	$this->e = null;
	var_dump($this);
    }
}
?>
Output :
object(C)#1 (2) {
  ["e"]=>
  NULL
  ["e2"]=>
  NULL
}
// "e2" has been deleted when $this->e =null; which is not correct IMHO
Similar example works correctly :
php -r '$a=new stdclass();$b=$a; $a=null; var_dump($a,$b);'

Please try using this CVS snapshot:

  http://snaps.php.net/php5-latest.tar.gz
 
For Windows:
 
  http://snaps.php.net/win32/php5-win32-latest.zip

No feedback was provided for this bug for over a week, so it is
being suspended automatically. If you are able to provide the
information that was originally requested, please do so and change
the status of the bug back to "Open".