The machine is accepting cookies from other sites ...

The sites that you're getting cookies from may have a "security certificate." A site that has a cert will be permitted to drop cookies on you. Mudcat doesn't have a certificate, so IE - and likely other browsers and/or cookie blockers - will apply more "strict rules" to whether the cookie is accepted.

The change above - putting mudcat.org in your browser's "exceptions" file - will override the requirement for a certificate and will allow you to keep a mudcat cookie.

John