原因是 Zend Server 在安装完后，安装目录中对应的 \Zend\ZendServer\etc\ZendEnablerConf.xml 文件的第一行出现了乱码，导致 Zend Server 不能完全启动，出现如下错误：

Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator, admin@example.com and inform them of the time the error occurred, and anything you might have done that may have caused the error.

More information about this error may be available in the server error log.

解决方法：我们可以将第一行的乱码改回正常的格式，把：

锘??xml version="1.0" encoding="UTF-8"?>

改为：

<?xml version="1.0" encoding="UTF-8"?>

保存后重启服务器即可解决。