custom Internet Shortcut icons

My Windows XP system has several Internet shortcuts on the desktop with custom icons, such as the shortcuts to http://www.google.com and to http://www.sms.ac Those icons are automatically downloaded from the websites when you save them into your Favorites folder. For some reason, however, those custom icons keep reverting to the standard Internet shortcut icon - the blue e on a white-blue background. After the computer restarts, however, the original icons come back - for a while ... In Welshjim's reply to arkie he said that Favicons were stored in the Temporary Internet Files folder and therefore were deleted when you empty the cache. However, these icons seem to be permanent files in the Favorites folder. Do you happen to know why they revert to the default icons and whether and how it can be prevented? Thanks.