Description:
------------
PHP: 5.1.2 from dotdeb.org (this isn't an option in the <select>)
Apache: 1.3.33
APC: 3.0.8
OS: Debian Sarge

Whenever I load my sample page for the second time (after caching), Apache segfaults. The problem appears to be related to the instanceof operator and/or the ArrayAccess interface.

The problem only appears when I instantiate sg2, which must extend sg2 and must be included from a separate file. Then when using the ArrayAccess interface on the resulting sg2 object, Apache segfaults.

Reproduce code:
---------------
file: page.html
--------------------
<?
class sg1 implements ArrayAccess
{
  protected $row = array();

  public function __construct($row)
  {
    $this->row = $row;
  }

  public function offsetUnset($index) {}
  public function offsetExists($index) {}
  public function offsetSet($index, $value) {}
  public function offsetGet($index)
  {
    return $this->row[$index];
  }
}
require_once 'sg2.php';

$sg2 = new sg2(array('title' => 'foobar'));
$title = $sg2['title'];
?>

file: sg2.php
--------------------
<?
class sg2 extends sg1 {}
?>

Expected result:
----------------
The page should finish loading every time.

Actual result:
--------------
On the second load (after the page is cached) Apache segfaults. GDB backtrace as follows:

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 16384 (LWP 32216)]
0x407446f0 in instanceof_function_ex () from /usr/lib/apache/1.3/libphp5.so
(gdb) bt
#0  0x407446f0 in instanceof_function_ex () from /usr/lib/apache/1.3/libphp5.so
#1  0x4074478c in instanceof_function () from /usr/lib/apache/1.3/libphp5.so
#2  0x40744748 in instanceof_function_ex () from /usr/lib/apache/1.3/libphp5.so
#3  0x4075ef1e in zend_std_read_dimension ()
   from /usr/lib/apache/1.3/libphp5.so
#4  0x40762053 in zend_get_compiled_variable_value ()
   from /usr/lib/apache/1.3/libphp5.so
#5  0x407a4f2f in execute () from /usr/lib/apache/1.3/libphp5.so
#6  0x407626f8 in execute () from /usr/lib/apache/1.3/libphp5.so
#7  0x4074791a in zend_execute_scripts () from /usr/lib/apache/1.3/libphp5.so
#8  0x40708aef in php_execute_script () from /usr/lib/apache/1.3/libphp5.so
#9  0x407c524e in apache_php_module_main () from /usr/lib/apache/1.3/libphp5.so
#10 0x407c5e6c in apache_php_module_main () from /usr/lib/apache/1.3/libphp5.so
#11 0x407c6021 in apache_php_module_main () from /usr/lib/apache/1.3/libphp5.so
#12 0x080553c3 in ap_invoke_handler ()
#13 0x08068465 in ap_some_auth_required ()
#14 0x08068614 in ap_process_request ()
#15 0x08060bd2 in ap_child_terminate ()
#16 0x08060e9a in ap_child_terminate ()
#17 0x08060f10 in ap_child_terminate ()
#18 0x08061a9a in ap_child_terminate ()
#19 0x08061ff8 in main ()