I have a server hosting which is a Dual Xeon Windows 2003 web edtion IIS6 with Plesk 7.0. From everywhere I read, php ISAPI is way faster than CGI, the default install using php.exe. On my Dual Xeon Window, a 1000 user online forum has killed the server many times, more than 50 php.exe processes show up in the process monitor. With some MySQL tunnng, the server now barely live on with 80 % CPU and 70% memory full. I did try to download the php and put it in a different folder than Plesk's. And configurate ISAPI extension as according to http://www.visualwin.com/PHP-ISAPI/ but not luck. The page always get this error: "Warning: main(./include/common.php): failed to open stream: No such file or directory" as shown in http://ins.si-fu.net/ and the phpinfo http://ins.si-fu.net/phpinfo.php. If I change the code to replace the line "./include/common.php" to "include/common.php" then it works. But there are way too many to change and some code is compiled by Zend I can't even read it. However, a test on a Windows 2003 without Plesk (another server I have and I removed Plesk), the ISAP works fine with the same forum page. The same result I tested on my desktop PC (Windows XP) worked fine. So it must be something in Plesk that has caused this. I understand Plesk 7.5 come with PHP ISAPI support, however, due to condiftion with my hosting and this is a live site, I am not able to upgrade 7.5. Any solutions, has this problem bee reported before?