While reading my own post in IE6, I saw the bug fooling around my page (hover the mouse over the link marked as external to see it in action).
To make the flicker dissapear (mouse over the A tag having background image) use this bookmarklet (copy/paste the code in your address bar in IE):
javascript:void(document.execCommand("BackgroundImageCache",false,true))
See http://www.mister-pixel.com/ for details.