Administrator account no longer has Administrator Privileges?

Ok, here at the office, we had a major lightning strike that ran in through the cable modem, and fried most of our networking gear.... including several LAN cards, and our Dell PowerEdge server, which is now in the shop.

So, here's our problem: Someone here was trying to setup their machine to logon to our old server's domain (we kept the old NT box around as a backup). In the process of doing so, they have somehow configured this computer in such a way that the Administrator account no longer has any administration privileges! I can't go in and change any of their network settings, perform a system restore, or alter the user accounts at all. :|

And at the login, I no longer have the option to log on to any domains. I can only enter a username and password. >Options doesn't bring up any alternative fields. ANd I can't login as any of the other users on this box!

Are there ANY ideas out there as to what I can do to rectify this? I've also noticed that the machine is configured to access a workgroup, which is also wrong... but, of course, I can't change the fact now.