Even if you didn't tell your InnoSetup to request elevation Vista would sniff it out and determine it to be a legacy installer and request elevation anyway unless you got funky about things like the EXE name it uses. Running as Admin is needed anyway, but won't solve this problem.

You need a step in your setup that creates the folder and sets the permissions on it.


Even if you run the installed program under an admin account, unless you run it "as Admin" (i.e. requesting elevation) it runs as a standard user.
But is all of this something that would only cause a problem on certain, newer, Vista computers?

The app runs fine on several "older" ones...