I see that all of the time, especially on laptops that get moved from one location to another. It bugs me as I have no idea how to stop it from happening. Renaming it in Sharing is the only workaround that I know of, and sometimes that doesn't stick. This gives a few sceanrios, any of it apply to what you do with the computer? Multiple sharing protocols enabled seems to be the big thing.

It seems to be a bug in Apple's networking, it's like it remembers old network connections and gets confused. I have read where their bonjour implementation may be a culprit. It causes problems when one is using printer sharing, the machines can't see the shared printers anymore.

This has been going on for a long time, at least through Leopard, can't remember if Tiger did it.