This can be caused by attempting to display a dialog with a Hyperlink control using Windows Installer 4.5 or earlier. The Hyperlink control requires Windows Installer 5.0. In this case, author two versions of the dialog, one with the control and one without. Use conditional statements to display the dialog box without the control if the VersionMsi property is less than �5.00�. Display the dialog with the Hyperlink control if VersionMsi is greater than or equal to �5.00�.