500内部服务器错误。 保存配置时 - IIS7

My site is in Joomla 3 and I am getting strange error when I try to save Global Configuration from Administrator.

I have tried removing .htaccess file and also tried disabling SEO friendly URLs.

Note that all other components/modules are working perfectly, it is only Global Config that gives me error.

PS: I have Remote Desktop Access to server so I captured this screen from that server. It includes all info, that might help you guys to help me.

OS: Windows Server 2008 R2

Web Server: IIS7