VISTA Enigma

I should first start off by saying, I'm still in the midst of testing,
but here is what appears to be happing with our application
installation process and subsequent update process(es) on Vista...

We have and installation that we attempt to install as a Standard User
with UAC enabled. We supply Admin credentials, and the installation
appears to go through without incident. The installation writes stuff
all over the board, but of particular interest or involvement in my
current situation is an .ini file that holds version information and
it created/updated in the installing users Application Data profile
area.

Like I said, all appears fine until we hit the update processing. We
have an update.exe that basically queries .ini files and determines if
an update .msi should be fired to update our 'client' application.
Here was the first problem... the utility looks to the user's profile
at the .ini file mentioned above. However, we must supply Admin
credentials here too, which causes the search for the .ini file to
look in the credential providing user's profile instead of the actual
installing Standard User's profile.

We thought we could get around that by simply adding the .ini file to
the Allusers Profile (ProgramData) area and tweaking our utility,
which seemed to fire off and execute the update properly. However,
following update upon initial initiation of the application, the
Windows Installer self repair is initiated. After checking the event
log, it appears the self repair was caused by missing profile
information in the credential providing user area (Admin). Nothing
appeared to be lacking in the Standard User area.

Why did this happen? Was it caused by using the ProgramData area?
Upon supplying Admin credentials to our update utility, does it act as
though our application should be installed for the Admin user instead
of the update process initiating Standard User?

Once the self repair completes, all seems OK, but I don't really know
what the state of the application is with regard to users now.

Everytime I believe I have a grasp on Vista and user/security, I see
things I just can't explain. If anyone needs additional information
to decipher and possibly help in solving my problem, please feel free
to ask!

Any help, as always is GREATLY appreciated!!