If you right click on an executable in Windows Vista, you’ll find a Compatibility Tab, where you can set compatibility modes (layers) for that executable file. These compatibility layers are collections of shims and loader flags (depending on whether they affect the loader or if they have to intercept Windows API calls throughout the lifetime of the process). However, you’ll find that you can’t do the same thing for MSI files on Windows Vista. With Windows 7, however, you’ll find that you *are* able to apply a compatibility mode. Is this using the same mechanisms? How does it work?

Full Article: MSDN Blog