Windows 7: windows 7 desktop icon size

Hi,
I have created a group policy which is copying some shortcuts on user desktops and then with the help of startup script I am increasing the icon size.
everything is working fine except that when the script is running to increase icon size, some are increasing but some are not. and this pattern is not consistent I mean on some computers lets say icon for "a" "b" and "c" is increasing but for "d" "e" will not while on some computers "e" "d" is ok but "a" "b" "c" are not.
If I am manually selecting the icon by right clicking the shortcuts then it is fine, so it means there is nothing wrong with .ico file.
can someone help me to overcome this problem or there is any registry permissions or settings need to do on client side?
where does the windows 7 is saving information about the icons?