web下载的dll文件无法加载进项目

问题：

警告 1 Could not load the assembly file:///C:UsersadminDesktopMapPrintingV5MapPrintingSilverlightSystem.Windows.Controls.Toolkit.dll. This assembly may have been downloaded from the Web. If an assembly has been downloaded from the Web, it is flagged by Windows as being a Web file, even if it resides on the local computer. This may prevent it from being used in your project. You can change this designation by changing the file properties. Only unblock assemblies that you trust. See http://go.microsoft.com/fwlink/?LinkId=179545 for more information. 

解决方式：

1、关闭VS2010；

2、找到无法加载的dll文件（System.Windows.Controls.Toolkit.dll），右击——>属性——>"常规"界面——>解除锁定，应用——>确定

3、重新打开VS项目。