Adding a file or page might require repeating some of the roll forward. 添加文件或页可能需要重复某些前滚。
This behavior occurs because Windows Setup requires additional files and folders to be present in the installation directory. 以上是微软的网站对此问题出现做出的解释,意思就是说系统安装需要在目前的安装目录里添加文件和文件夹。