php5.dll 无法找到

Hi All
I installed zend Guard to encode some php version 5.3 code, and the installed the loader for php 5.3(zendLoader.dll), and then add 
zend_extension="C:\xampp\php\ext\ZendLoader.dll"
; Enables loading encoded scripts. The default value is On
zend_loader.enable=1 
to php.ini file
i currently use xampp 1.7, but after adding the above code, i get the following message when trying to start xampp:
This application has failed to starts because php5.dll was not found 
note that when i remove the line zend_extension="C:\xampp\php\ext\ZendLoader.dll" and restart the server it will work without any problems
Any Help Please 
Thank You

Hello

Zend Loader is compiled for PHP 5.3 non-thread-safe.
If you look at the phpinfo() or try from command line under PHP dir,
php -i | find "Thread"
You will probably see that Xampp is using PHP Thread Safe (enabled).

You can load Zend Loader within PHP 5.3 "VC9 x86 Non Thread Safe" version:
http://windows.php.net/download/

As an alternative, I suggest to install Zend Server on your Windows machine,
for true supporting runtime of Zend Guard encoded scripts and many other benefits included in the Zend Server stack.
http://www.zend.com/en/products/server/editions