搭建WP7开发环境的时候，安装了几次，都出现".NET Framework 4 could not install"的错误，然后直接安装.NET Framework 4就报了“HRESULT 0xc8000222”这个错误，最后上官网查了下，终于找到了解决方法：

This behavior may occur if the temporary folder of Windows Update has been corrupted. We can refer to the following steps to rename this folder. Please be assured the folder will be created again when we visit the Windows Update site again.

1. Click Start, Run, type: cmd and press Enter. Please run the following command in the opened window.

关闭Windows Update服务
net stop WuAuServ

2. Click Start, Run, type: %windir% and press Enter.
3. In the opened folder, rename the folder SoftwareDistribution to SDold.
4. Click Start, Run, type: cmd and press Enter.

Please run the following command in the opened window.

关闭Windows Update服务
关闭Windows Update服务
关闭Windows Update服务
打开Windows Update服务

net start WuAuServ

然后重新安装，一切顺利！

      搭建WP7开发环境的时候，安装了几次，都出现".NET Framework 4 could not install"的错误，然后直接安装.NET Framework 4就报了“HRESULT 0xc8000222”这个错误，最后上官网查了下，终于找到了解决方法：

This behavior may occur if the temporary folder of Windows Update has been corrupted. We can refer to the following steps to rename this folder. Please be assured the folder will be created again when we visit the Windows Update site again.

1. Click Start, Run, type: cmd and press Enter. Please run the following command in the opened window.

关闭Windows Update服务
net stop WuAuServ

2. Click Start, Run, type: %windir% and press Enter.
3. In the opened folder, rename the folder SoftwareDistribution to SDold.
4. Click Start, Run, type: cmd and press Enter.

Please run the following command in the opened window.

关闭Windows Update服务
关闭Windows Update服务
关闭Windows Update服务
打开Windows Update服务

net start WuAuServ

然后重新安装，一切顺利！