Installed IE7, and icons disappeared!!

Okay, here's a really weird one that I am at a total loss to understand. Like most people, I have customized my Favorites folders with individually selected icons for internet shortcuts ... some home-made using icon software. I have just upgrated from IE6 to IE7, and all of the internet shortcut icons have diappeared, to be replaced by a generic IE7 icon. What's more, it won't let me replace the generic icon with anything else. However, when I switch from Tile, Thumbnail or Icon view to List or Details view, the original IE6 icons (including the home-made ones) are back!!

Anyone know what up with that???