To turn this off for all files, navigate to Tools>>Options>>Security and uncheck the box next to the Prevent executing untrusted VIs or loading untrusted executable code files option.
Alternatively, you can choose specific folders to trust. Choose the Manage Trusted Files option from the error window, this will open a new dialog. Go to View>> All Trusted Files. It may take a moment to load. You can then choose Add Files... or Add All Files in Folder... to open the operating system file dialog and navigate to the files or folders you want to trust.
