Internet Explorer and missing images

I struggled with this issue and thought I'd help out the next person even though the solution was easy and known.

After a recent PeopleTools patch we had several users who were missing the icon for expandable group boxes, ie the little grey triangle.  The group box was still expandable by clicking on the html area where the icon should have been.

I knew this was cache issue and even fixed a few users by having them clear their cache but I still had users that couldn't see the image.

It turns out that when you clear cache in IE it's very important to deselect the "Preserve Favorites website data" at the top.