1. Step Open the registry editor by entering regedit.exe into the search bar
2. Step Uncollapse the registry and go to HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows\Installer
3. Step If that folder “Installer” does not exist you have a different problem, but if the folder exists and on the right pane you see the entry DisableMSI then right-click on it and click delete
4. Step You can now properly install MSI files on Windows 7
If you still have problems despite deleting it, let us know what error message you receive below