The one change we made was to change the network id from domain: mitre.org to workgroup: WORKGROUP. In hindsight, it makes perfect sense: the password I'm using is for the mitre.org domain, and it's now looking for the password I was using before I joined that domain.
On the plus side, that was only ~six months ago (for various reasons I wasn't actually part of the right domain for most of the time I've worked there). On the minus side, I was changing my password every 30 days, so I have no idea now what it was. I've tried all the passwords I can remember using, and of course none of them work.
So, anyone know how to hack win2k? :)