I answered to this same question a few days ago.. here is the info :
http://www.softpedia.com/get/Security/Lockdown/Microsoft-Private-Folder.shtml
you have to use the command prompt in administrator mode...
to do that go to start>accessories>RIGHT CLICK on the command prompt and
select run as administrator..
then via the command prompt navigate to the installer package and run it...
the program will install and work.
to change a directory you have to write:
cd NAME OF FOLDER for example
CD DESKTOP
and to go to a parent folder you have to type:
CD..
that is CD with 2 dots afterwards... the best way to do it is this:
Place the installer in the root of your drive C
then press CD.. enter CD.. enter untill you are at C:\
and then type the name of the installer along with its extension, for
example
MSPF10ENU.msi and press enter
the installer will start..