>>Are you also using C:\appname as the target for the shortcut?
>
>Yep

If you use a fixed drive and path for the target of the shortcut, it's not going to change if the user selects another installation drive and/or path at setup time. You can still use C:\appname as the default value for INSTALLDIR on the General Information page, but if you want your shortcut to change when INSTALLDIR changes, use [INSTALLDIR]appname.exe as the target for the shortcut.