Installed PHP 5.0.5 and Apache 2.0.54 [listening on port 8088] last night under Windows XP Professional [with IIS]. When installing the Discuz forum today, I was asked to install Zend-Optimizer to support encrypted PHP files. Download the Win32 installation file of Zend-Optimizer 2.5.7 When installing, it started smoothly Apache Root and php.ini selection paths are: E:/Program Files/Apache Group/Apache2 E:/PHP5 But when I need to restart Apache later, the restart fails. I restart it manually. It prompts that the installation is successful. However, when I check in phpinfo.php, I find that Optimizer is not associated with PHP. The prompt information about Zend is: Zend Engine v2.0.5, Copyright(c) 1998-2004 Zend Technologies. There is no Optimizer information. Encrypted files cannot be executed correctly. At first I thought it was a problem with Apache restarting. After repeated tests, I found that Apache was normal. Later, I searched online and found no relevant solutions. Then I suddenly thought that I had copied a Php.ini file to the C:/Windows directory. I wonder if it is the ini file actually used. Try to reinstall Optimizer and select C:/Windows for the ini file path. Or restart Apache manually. After installation, check phpinfo.php, the Zend prompt message is Zend Engine v2.0.5,Copyright (c) 1998-2004 Zend Technologies. With Zend Extention Manager v1.0.6,Copyright(c) 2003-2004,by Zend Technologies With Zend Optimizer v2.5.7,Copyright(C) 1998-2004,by Zend Technologies Optimizer was successfully installed and the encrypted files were normal when executing Discuz! Summary: When installing Optimizer, the php.ini file must select the one actually used when installed in the Windows directory. In fact, it prompted C:/Windows during installation, but I did not pay attention, which led to the installation Failure.