Rebuild the icon cache
This is a feature of some of these and other apps. What's being done is, the hidden "shelliconcache" file (no extension, and a hidden file) in your windir gets deleted. This cache gets corrupted once in a while. You can do that yourself but you'll need to restart to refresh explorer, and to recreate the file. This function refreshes explorer and the file immediately.
It's also available as a standalone program. RebIC removes any old images from memory and is available from ArcaneWooD Software (free, Win 9x). Great when you've been fooling around without using any app: put a shortcut in your quicklaunch bar (add "-close" to the path).