How to stop shortcut icons changing

Hi,

I'm getting quite frustrated with my internet explorer shortcuts: I have a
custom toolbar with shortcuts to frequently used sites, and I have changed
the icons to make them clearer. However, for some of these icons, whenever I
use the shortcut, the icon is immediately changed to the favicon for the
site, which can often be unsightly or unclear at the larger toolbar size. I'm
sure I found a way to stop them automatically updating, but am unable to
remember or find how! I tried making them read only, and limiting system
permissions, to no avail. Please help!

Thanks