The Voicepack 3.1 seems to be discontinued. Because of that Windows 8.1 is having a hard time using it. Same thing applies to you. If you don't have an updated version, Windows 8.1 will refuse to install or run the application. The best thing you can do is to use a compatibility tweak for the software. Right click it then go to Properties > Compatibility and select a version of Windows older than Windows 8.1 or Windows 8.
