you need to run it as adminstrator, just beeing adminstrator isn't enought in vista & win7.
you need to hit "run as adminstrator" by right clicking the file, opening a file with adminstrator profile doesn't run it as adminstrator
propably you are even more confused but read this

other way to bypass this is just installing it under user subfolder (pictures, desktop, documents etc.)
€: and I'm aware this solved but just to point it out.
This post was edited by MikkoU on Aug 1 2011 09:39am