Thank you for this bug report. To properly diagnose the problem, we
need a short but complete example script to be able to reproduce
this bug ourselves. 

A proper reproducing script starts with <?php and ends with ?>,
is max. 10-20 lines long and does not require any external 
resources such as databases, etc. If the script requires a 
database to demonstrate the issue, please make sure it creates 
all necessary tables, stored procedures etc.

Please avoid embedding huge scripts into the report.

Here you are:

Expected result:
----------------
PHP 5.3.9RC1 prints: Microsoft Windows


Actual result:
--------------
PHP 5.4.0RC1 crash


<?php
 $z=50;while($z--){

  $o=new COM('WinMgmts:',null,CP_UTF8);
  foreach($o->ExecQuery('SELECT * FROM Win32_OperatingSystem') as $x){
   $o=$x->Caption;
  }

 }

 print($o);
?>

corrected version:

<?php
 $z=50;while($z--){

  $o=new COM('WinMgmts:',null,CP_UTF8);
  foreach($o->ExecQuery('SELECT * FROM Win32_OperatingSystem') as $x){
   $s=$x->Caption;
  }

 }

 print($s);
?>

FIXED, testes on PHP 5.4 Revision 319806
I close this bug.