I think, if you are using ISS installer, that you need to tell it to run
as administrator for the PrivilegesRequired flag.  Seems like a trivial
change to me.  What do you think??

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here is a copy of their documentation:

A typical Inno Setup installation running on Windows NT/2000/XP/2003
does not require administrative or "power user" privileges. However,
there are exceptions as noted below.

Things that require administrative privileges on both Windows
NT/2000/XP/2003:

    Using "PrivilegesRequired=admin" in the script's [Setup] section.
This causes Setup to abort with an error message if the user lacks
administrative privileges.
    Using the "restartreplace" flag in the [Files] section. This flag
causes Inno Setup to call the MoveFileEx function, which attempts to
write to "HKEY_LOCAL_MACHINE\ SYSTEM\ CurrentControlSet\ Control\
Session Manager". Write access to this key is restricted to Administrators.
    Writing to any key under HKEY_USERS\.DEFAULT using the [Registry]
section. Write access to this key is restricted to Administrators.

Things that require either administrative or "power user" privileges on
Windows 2000/XP/2003:

    Using "PrivilegesRequired=poweruser" in the script's [Setup]
section. This causes Setup to abort with an error message if the user
lacks either administrative or "power user" privileges.
    Using the "regserver" flag in the [Files] section. In most cases
registering a DLL involves writing to HKEY_CLASSES_ROOT, a privilege not
granted to ordinary users.
    Using the "sharedfile" flag is the [Files] section. This flag causes
Inno Setup to create/update a value in "HKEY_LOCAL_MACHINE\ SOFTWARE\
Microsoft\ Windows\ CurrentVersion\ SharedDLLs". Ordinary users are not
allowed to write to that key.
    Using the FontInstall parameter in the [Files] section.
    Writing to any key under HKEY_LOCAL_MACHINE or HKEY_CLASSES_ROOT
using the [Registry] section. Ordinary users are not allowed to write to
those keys.