Favicon annoyance

I recently created a little customized icon for our web site so that people with IE 5 would get something when they bookmarked. Actually, I really made it because I didn't want to see Error 404 (Missing file) /favicon.ico in my web logs. Anyway, first I made a test icon to see if it would work, then I replaced it with the real icon. However, my browser continues to show the first icon I created no matter what I do. That icon does not exist anymore, yet the browser continues to show it. I have replaced the icon on the server, rebookmarked, deleted the bookmark and bookmarked it again, deleted every single temporary internet file on my computer, etc etc.

I guess my question is this: How can I get my browser to recognize the new icon? Its like the browser hardwired the old icon into the memory and continues to show it even though it doesn't exist anymore. Oh, and I have rebooted also. Any help would be appreciated.