needhelpfast569--My short experience with trying to change icons for shortcuts in Win7 suggests that Win7 works differently from XP. You may want to consider using a third party app.
http://www.microangelo.us/mod.aspIt is not clear how Win7 associates an icon with a shortcut. In your case the custom association fails after some action (like a shutdown) and reverts to the default. Other than using a third party app, I do not know how to make the custom change permanent.