Dialog Designer: WebView requires Dialog Designer Version 3.1 or higher, which is normally installed during the installation of ArcView GIS. However, if there has been an older version of Dialog Designer on your computer, this version might not be upgraded when installing ArcView GIS 3.1 or higher. In this case you'll get an error message when starting WebView. Download Dialog Designer update here and extract the files to the $AVHOME-directory (usually c:\esri\AV_GIS30\ArcView).