I have to admit that I'm a little puzzled whenever this happens on a well-known site. Do not all registrars allow you to set up auto-renew on your domains? I have to explicitly choose not to renew a domain.
The latest I've heard is that it wasn't due to expire for another year, but Network Solutions decided it was expiring anyway.
http://article.gmane.org/gmane.comp.lang.haskell.general/184...