[Value data type] REG_DWORD [Description] If this policy value is not set, the installer searches the registry for products in the following order: managed products that are registered as per-user, unmanaged products that are registered as per-user, and finally products that are registered as per-machine. If this policy value is set to 1, the installer ignores all products that are registered as per-user and only searches for products that are registered as per-machine. An attempt to perform a per-user installation causes the installer to display an error message and stops the installation. [Policy] 
DisableUserInstalls