When users attempted to install the older Prism 4.0 on the newer Vista platform, they encountered a clash of philosophies: an application designed for a permissive environment running on a restrictive, security-heavy operating system.
The most common fix for installation failure is running the setup file as an Administrator. In Windows XP, double-clicking an installer usually sufficed. In Vista, you must right-click the Setup.exe file (or the autorun file on the CD-ROM) and select This bypasses UAC temporarily and allows the installer to write the necessary system files.