By default, a Visual Basic Windows-based application includes an App.config file. There will be a problem when a user tries to install from a Web server that uses Windows Server 2003, because that operating system blocks the installation of .config files for security reasons. To enable the .config file to be installed, click Use ".deploy" file extension in the Publish Options dialog box.
You also must set the content types (also known as MIME types) appropriately for .application, .manifest, and .deploy files. For more information, see your Web server documentation.
Regards,
Rachel Gomez