Security Warning for Project Dialog Box
The Security Warning for Project dialog box appears if you open a project that has been downloaded from the internet, or if you create a new project or open an existing project by using a Universal Naming Convention (UNC) path.
If you click OK, the dialog box will not appear again for the same project when it’s loaded as part of the same solution by the same user on the same machine (assuming the hidden .suo file isn’t deleted).
To prevent this dialog box from appearing, select Options from the Tools menu, and then in the Options dialog box select Show all settings, select General under Projects and Solutions, and clear the Warn user when the project location is not trusted checkbox.
Projects Downloaded from the Internet
For projects that you download from the internet, another way to prevent the Security Warning for Project dialog box from appearing is by unblocking the .zip file before you extract the project. For more information, see How to: Use an Assembly from the Web in Visual Studio. (The page is about assemblies, but the unblocking procedure is the same for .zip files.)
Projects Opened on UNC Paths
By default, a UNC path is not a trusted location for a project. To prevent the Security Warning for Project dialog box from appearing each time a new user opens a project on a UNC path, either clear the Warn user when the project location is not trusted checkbox or move the project to a trusted location that you can reference without using a UNC path.