Why do the icons of my bookmarks disappear after a while?

The thread title says it all realy. I know there is software that finds those small icons again, but I wonder why they vanish?

Firefox, IE, Opera, AOL…

Windows, Mac, Linux…

Or shall we guess?

They get cleared from the cache? Favicon gnomes?

  1. Steal favicons
  2. ???
  3. Profit!

IE6, FF2, XPpro
It doesn’t matter. I handle quite a few computers in a day and while favicons restores them, I still wonder why they go away.

It’s built into Windows that they have some sort of shelflife, for some ridiculous reason. It might be something to do with how often your browser Temp files get flushed.

Mine didn’t diasappear the other day- they all got sorted against the wrong bookmark. And the wrong ones were coming up in the banner of the site. I.E.

With me (Fire Fox), they don’t disappear, they just are the wrong icons sometimes. The Straight Dope Front Page, for instance, has Google’s icon. And a radio station has the Onion’s icon.

It’s not a shelflife, per se, but each site can specify a replacement icon. IE browsers honor this. Other browsers may let you keep the ones you’ve chosen.

This still irks me. I like my Yahoo mail icon to look like a mailbox, but whenever I use IE to access it, it reverts to their generic “Y!”, same a their map page and their Yellow pages page… So I can’t use the icons as intended, to visually distinguish pages.